Source file src/cmd/go/internal/test/test.go

     1  // Copyright 2011 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package test
     6  
     7  import (
     8  	"bytes"
     9  	"context"
    10  	"errors"
    11  	"fmt"
    12  	"internal/coverage"
    13  	"internal/platform"
    14  	"io"
    15  	"io/fs"
    16  	"os"
    17  	"os/exec"
    18  	"path/filepath"
    19  	"regexp"
    20  	"slices"
    21  	"strconv"
    22  	"strings"
    23  	"sync"
    24  	"sync/atomic"
    25  	"time"
    26  
    27  	"cmd/go/internal/base"
    28  	"cmd/go/internal/cache"
    29  	"cmd/go/internal/cfg"
    30  	"cmd/go/internal/load"
    31  	"cmd/go/internal/lockedfile"
    32  	"cmd/go/internal/modload"
    33  	"cmd/go/internal/search"
    34  	"cmd/go/internal/str"
    35  	"cmd/go/internal/trace"
    36  	"cmd/go/internal/work"
    37  	"cmd/internal/test2json"
    38  
    39  	"golang.org/x/mod/module"
    40  )
    41  
    42  // Break init loop.
    43  func init() {
    44  	CmdTest.Run = runTest
    45  }
    46  
    47  const testUsage = "go test [build/test flags] [packages] [build/test flags & test binary flags]"
    48  
    49  var CmdTest = &base.Command{
    50  	CustomFlags: true,
    51  	UsageLine:   testUsage,
    52  	Short:       "test packages",
    53  	Long: `
    54  'Go test' automates testing the packages named by the import paths.
    55  It prints a summary of the test results in the format:
    56  
    57  	ok   archive/tar   0.011s
    58  	FAIL archive/zip   0.022s
    59  	ok   compress/gzip 0.033s
    60  	...
    61  
    62  followed by detailed output for each failed package.
    63  
    64  'Go test' recompiles each package along with any files with names matching
    65  the file pattern "*_test.go".
    66  These additional files can contain test functions, benchmark functions, fuzz
    67  tests and example functions. See 'go help testfunc' for more.
    68  Each listed package causes the execution of a separate test binary.
    69  Files whose names begin with "_" (including "_test.go") or "." are ignored.
    70  
    71  Test files that declare a package with the suffix "_test" will be compiled as a
    72  separate package, and then linked and run with the main test binary.
    73  
    74  The go tool will ignore a directory named "testdata", making it available
    75  to hold ancillary data needed by the tests.
    76  
    77  As part of building a test binary, go test runs go vet on the package
    78  and its test source files to identify significant problems. If go vet
    79  finds any problems, go test reports those and does not run the test
    80  binary. Only a high-confidence subset of the default go vet checks are
    81  used. That subset is: atomic, bool, buildtags, directive, errorsas,
    82  ifaceassert, nilfunc, printf, stringintconv, and tests. You can see
    83  the documentation for these and other vet tests via "go doc cmd/vet".
    84  To disable the running of go vet, use the -vet=off flag. To run all
    85  checks, use the -vet=all flag.
    86  
    87  All test output and summary lines are printed to the go command's
    88  standard output, even if the test printed them to its own standard
    89  error. (The go command's standard error is reserved for printing
    90  errors building the tests.)
    91  
    92  The go command places $GOROOT/bin at the beginning of $PATH
    93  in the test's environment, so that tests that execute
    94  'go' commands use the same 'go' as the parent 'go test' command.
    95  
    96  Go test runs in two different modes:
    97  
    98  The first, called local directory mode, occurs when go test is
    99  invoked with no package arguments (for example, 'go test' or 'go
   100  test -v'). In this mode, go test compiles the package sources and
   101  tests found in the current directory and then runs the resulting
   102  test binary. In this mode, caching (discussed below) is disabled.
   103  After the package test finishes, go test prints a summary line
   104  showing the test status ('ok' or 'FAIL'), package name, and elapsed
   105  time.
   106  
   107  The second, called package list mode, occurs when go test is invoked
   108  with explicit package arguments (for example 'go test math', 'go
   109  test ./...', and even 'go test .'). In this mode, go test compiles
   110  and tests each of the packages listed on the command line. If a
   111  package test passes, go test prints only the final 'ok' summary
   112  line. If a package test fails, go test prints the full test output.
   113  If invoked with the -bench or -v flag, go test prints the full
   114  output even for passing package tests, in order to display the
   115  requested benchmark results or verbose logging. After the package
   116  tests for all of the listed packages finish, and their output is
   117  printed, go test prints a final 'FAIL' status if any package test
   118  has failed.
   119  
   120  In package list mode only, go test caches successful package test
   121  results to avoid unnecessary repeated running of tests. When the
   122  result of a test can be recovered from the cache, go test will
   123  redisplay the previous output instead of running the test binary
   124  again. When this happens, go test prints '(cached)' in place of the
   125  elapsed time in the summary line.
   126  
   127  The rule for a match in the cache is that the run involves the same
   128  test binary and the flags on the command line come entirely from a
   129  restricted set of 'cacheable' test flags, defined as -benchtime,
   130  -coverprofile, -cpu, -failfast, -fullpath, -list, -outputdir, -parallel,
   131  -run, -short, -skip, -timeout and -v.
   132  If a run of go test has any test or non-test flags outside this set,
   133  the result is not cached. To disable test caching, use any test flag
   134  or argument other than the cacheable flags. The idiomatic way to disable
   135  test caching explicitly is to use -count=1. Tests that open files within
   136  the package's module or that consult environment variables only
   137  match future runs in which the files and environment variables are
   138  unchanged. A cached test result is treated as executing in no time
   139  at all, so a successful package test result will be cached and
   140  reused regardless of -timeout setting.
   141  
   142  In addition to the build flags, the flags handled by 'go test' itself are:
   143  
   144  	-args
   145  	    Pass the remainder of the command line (everything after -args)
   146  	    to the test binary, uninterpreted and unchanged.
   147  	    Because this flag consumes the remainder of the command line,
   148  	    the package list (if present) must appear before this flag.
   149  
   150  	-c
   151  	    Compile the test binary to pkg.test in the current directory but do not run it
   152  	    (where pkg is the last element of the package's import path).
   153  	    The file name or target directory can be changed with the -o flag.
   154  
   155  	-exec xprog
   156  	    Run the test binary using xprog. The behavior is the same as
   157  	    in 'go run'. See 'go help run' for details.
   158  
   159  	-json
   160  	    Convert test output to JSON suitable for automated processing.
   161  	    See 'go doc test2json' for the encoding details.
   162  	    Also emits build output in JSON. See 'go help buildjson'.
   163  
   164  	-o file
   165  	    Save a copy of the test binary to the named file.
   166  	    The test still runs (unless -c is specified).
   167  	    If file ends in a slash or names an existing directory,
   168  	    the test is written to pkg.test in that directory.
   169  
   170  The test binary also accepts flags that control execution of the test; these
   171  flags are also accessible by 'go test'. See 'go help testflag' for details.
   172  
   173  For more about build flags, see 'go help build'.
   174  For more about specifying packages, see 'go help packages'.
   175  
   176  See also: go build, go vet.
   177  `,
   178  }
   179  
   180  var HelpTestflag = &base.Command{
   181  	UsageLine: "testflag",
   182  	Short:     "testing flags",
   183  	Long: `
   184  The 'go test' command takes both flags that apply to 'go test' itself
   185  and flags that apply to the resulting test binary.
   186  
   187  Several of the flags control profiling and write an execution profile
   188  suitable for "go tool pprof"; run "go tool pprof -h" for more
   189  information. The -sample_index=alloc_space, -sample_index=alloc_objects,
   190  and -show_bytes options of pprof control how the information is presented.
   191  
   192  The following flags are recognized by the 'go test' command and
   193  control the execution of any test:
   194  
   195  	-artifacts
   196  	    Save test artifacts in the directory specified by -outputdir.
   197  	    See 'go doc testing.T.ArtifactDir'.
   198  
   199  	-bench regexp
   200  	    Run only those benchmarks matching a regular expression.
   201  	    By default, no benchmarks are run.
   202  	    To run all benchmarks, use '-bench .' or '-bench=.'.
   203  	    The regular expression is split by unbracketed slash (/)
   204  	    characters into a sequence of regular expressions, and each
   205  	    part of a benchmark's identifier must match the corresponding
   206  	    element in the sequence, if any. Possible parents of matches
   207  	    are run with b.N=1 to identify sub-benchmarks. For example,
   208  	    given -bench=X/Y, top-level benchmarks matching X are run
   209  	    with b.N=1 to find any sub-benchmarks matching Y, which are
   210  	    then run in full.
   211  
   212  	-benchtime t
   213  	    Run enough iterations of each benchmark to take t, specified
   214  	    as a time.Duration (for example, -benchtime 1h30s).
   215  	    The default is 1 second (1s).
   216  	    The special syntax Nx means to run the benchmark N times
   217  	    (for example, -benchtime 100x).
   218  
   219  	-count n
   220  	    Run each test, benchmark, and fuzz seed n times (default 1).
   221  	    If -cpu is set, run n times for each GOMAXPROCS value.
   222  	    Examples are always run once. -count does not apply to
   223  	    fuzz tests matched by -fuzz.
   224  
   225  	-cover
   226  	    Enable coverage analysis.
   227  	    Note that because coverage works by annotating the source
   228  	    code before compilation, compilation and test failures with
   229  	    coverage enabled may report line numbers that don't correspond
   230  	    to the original sources.
   231  
   232  	-covermode set,count,atomic
   233  	    Set the mode for coverage analysis for the package[s]
   234  	    being tested. The default is "set" unless -race is enabled,
   235  	    in which case it is "atomic".
   236  	    The values:
   237  		set: bool: does this statement run?
   238  		count: int: how many times does this statement run?
   239  		atomic: int: count, but correct in multithreaded tests;
   240  			significantly more expensive.
   241  	    Sets -cover.
   242  
   243  	-coverpkg pattern1,pattern2,pattern3
   244  	    Apply coverage analysis in each test to packages whose import paths
   245  	    match the patterns. The default is for each test to analyze only
   246  	    the package being tested. See 'go help packages' for a description
   247  	    of package patterns. Sets -cover.
   248  
   249  	-cpu 1,2,4
   250  	    Specify a list of GOMAXPROCS values for which the tests, benchmarks or
   251  	    fuzz tests should be executed. The default is the current value
   252  	    of GOMAXPROCS. -cpu does not apply to fuzz tests matched by -fuzz.
   253  
   254  	-failfast
   255  	    Do not start new tests after the first test failure.
   256  
   257  	-fullpath
   258  	    Show full file names in the error messages.
   259  
   260  	-fuzz regexp
   261  	    Run the fuzz test matching the regular expression. When specified,
   262  	    the command line argument must match exactly one package within the
   263  	    main module, and regexp must match exactly one fuzz test within
   264  	    that package. Fuzzing will occur after tests, benchmarks, seed corpora
   265  	    of other fuzz tests, and examples have completed. See the Fuzzing
   266  	    section of the testing package documentation for details.
   267  
   268  	-fuzztime t
   269  	    Run enough iterations of the fuzz target during fuzzing to take t,
   270  	    specified as a time.Duration (for example, -fuzztime 1h30s).
   271  		The default is to run forever.
   272  	    The special syntax Nx means to run the fuzz target N times
   273  	    (for example, -fuzztime 1000x).
   274  
   275  	-fuzzminimizetime t
   276  	    Run enough iterations of the fuzz target during each minimization
   277  	    attempt to take t, as specified as a time.Duration (for example,
   278  	    -fuzzminimizetime 30s).
   279  		The default is 60s.
   280  	    The special syntax Nx means to run the fuzz target N times
   281  	    (for example, -fuzzminimizetime 100x).
   282  
   283  	-json
   284  	    Log verbose output and test results in JSON. This presents the
   285  	    same information as the -v flag in a machine-readable format.
   286  
   287  	-list regexp
   288  	    List tests, benchmarks, fuzz tests, or examples matching the regular
   289  	    expression. No tests, benchmarks, fuzz tests, or examples will be run.
   290  	    This will only list top-level tests. No subtest or subbenchmarks will be
   291  	    shown.
   292  
   293  	-outputdir directory
   294  	    Place output files from profiling and test artifacts in the
   295  	    specified directory, by default the directory in which "go test" is running.
   296  
   297  	-parallel n
   298  	    Allow parallel execution of test functions that call t.Parallel, and
   299  	    fuzz targets that call t.Parallel when running the seed corpus.
   300  	    The value of this flag is the maximum number of tests to run
   301  	    simultaneously.
   302  	    While fuzzing, the value of this flag is the maximum number of
   303  	    subprocesses that may call the fuzz function simultaneously, regardless of
   304  	    whether T.Parallel is called.
   305  	    By default, -parallel is set to the value of GOMAXPROCS.
   306  	    Setting -parallel to values higher than GOMAXPROCS may cause degraded
   307  	    performance due to CPU contention, especially when fuzzing.
   308  	    Note that -parallel only applies within a single test binary.
   309  	    The 'go test' command may run tests for different packages
   310  	    in parallel as well, according to the setting of the -p flag
   311  	    (see 'go help build').
   312  
   313  	-run regexp
   314  	    Run only those tests, examples, and fuzz tests matching the regular
   315  	    expression. For tests, the regular expression is split by unbracketed
   316  	    slash (/) characters into a sequence of regular expressions, and each
   317  	    part of a test's identifier must match the corresponding element in
   318  	    the sequence, if any. Note that possible parents of matches are
   319  	    run too, so that -run=X/Y matches and runs and reports the result
   320  	    of all tests matching X, even those without sub-tests matching Y,
   321  	    because it must run them to look for those sub-tests.
   322  	    See also -skip.
   323  
   324  	-short
   325  	    Tell long-running tests to shorten their run time.
   326  	    It is off by default but set during all.bash so that installing
   327  	    the Go tree can run a sanity check but not spend time running
   328  	    exhaustive tests.
   329  
   330  	-shuffle off,on,N
   331  	    Randomize the execution order of tests and benchmarks.
   332  	    It is off by default. If -shuffle is set to on, then it will seed
   333  	    the randomizer using the system clock. If -shuffle is set to an
   334  	    integer N, then N will be used as the seed value. In both cases,
   335  	    the seed will be reported for reproducibility.
   336  
   337  	-skip regexp
   338  	    Run only those tests, examples, fuzz tests, and benchmarks that
   339  	    do not match the regular expression. Like for -run and -bench,
   340  	    for tests and benchmarks, the regular expression is split by unbracketed
   341  	    slash (/) characters into a sequence of regular expressions, and each
   342  	    part of a test's identifier must match the corresponding element in
   343  	    the sequence, if any.
   344  
   345  	-timeout d
   346  	    If a test binary runs longer than duration d, panic.
   347  	    If d is 0, the timeout is disabled.
   348  	    The default is 10 minutes (10m).
   349  
   350  	-v
   351  	    Verbose output: log all tests as they are run. Also print all
   352  	    text from Log and Logf calls even if the test succeeds.
   353  
   354  	-vet list
   355  	    Configure the invocation of "go vet" during "go test"
   356  	    to use the comma-separated list of vet checks.
   357  	    If list is empty, "go test" runs "go vet" with a curated list of
   358  	    checks believed to be always worth addressing.
   359  	    If list is "off", "go test" does not run "go vet" at all.
   360  
   361  The following flags are also recognized by 'go test' and can be used to
   362  profile the tests during execution:
   363  
   364  	-benchmem
   365  	    Print memory allocation statistics for benchmarks.
   366  	    Allocations made in C or using C.malloc are not counted.
   367  
   368  	-blockprofile block.out
   369  	    Write a goroutine blocking profile to the specified file
   370  	    when all tests are complete.
   371  	    Writes test binary as -c would.
   372  
   373  	-blockprofilerate n
   374  	    Control the detail provided in goroutine blocking profiles by
   375  	    calling runtime.SetBlockProfileRate with n.
   376  	    See 'go doc runtime.SetBlockProfileRate'.
   377  	    The profiler aims to sample, on average, one blocking event every
   378  	    n nanoseconds the program spends blocked. By default,
   379  	    if -test.blockprofile is set without this flag, all blocking events
   380  	    are recorded, equivalent to -test.blockprofilerate=1.
   381  
   382  	-coverprofile cover.out
   383  	    Write a coverage profile to the file after all tests have passed.
   384  	    Sets -cover.
   385  
   386  	-cpuprofile cpu.out
   387  	    Write a CPU profile to the specified file before exiting.
   388  	    Writes test binary as -c would.
   389  
   390  	-memprofile mem.out
   391  	    Write an allocation profile to the file after all tests have passed.
   392  	    Writes test binary as -c would.
   393  
   394  	-memprofilerate n
   395  	    Enable more precise (and expensive) memory allocation profiles by
   396  	    setting runtime.MemProfileRate. See 'go doc runtime.MemProfileRate'.
   397  	    To profile all memory allocations, use -test.memprofilerate=1.
   398  
   399  	-mutexprofile mutex.out
   400  	    Write a mutex contention profile to the specified file
   401  	    when all tests are complete.
   402  	    Writes test binary as -c would.
   403  
   404  	-mutexprofilefraction n
   405  	    Sample 1 in n stack traces of goroutines holding a
   406  	    contended mutex.
   407  
   408  	-trace trace.out
   409  	    Write an execution trace to the specified file before exiting.
   410  
   411  Each of these flags is also recognized with an optional 'test.' prefix,
   412  as in -test.v. When invoking the generated test binary (the result of
   413  'go test -c') directly, however, the prefix is mandatory.
   414  
   415  The 'go test' command rewrites or removes recognized flags,
   416  as appropriate, both before and after the optional package list,
   417  before invoking the test binary.
   418  
   419  For instance, the command
   420  
   421  	go test -v -myflag testdata -cpuprofile=prof.out -x
   422  
   423  will compile the test binary and then run it as
   424  
   425  	pkg.test -test.v -myflag testdata -test.cpuprofile=prof.out
   426  
   427  (The -x flag is removed because it applies only to the go command's
   428  execution, not to the test itself.)
   429  
   430  The test flags that generate profiles (other than for coverage) also
   431  leave the test binary in pkg.test for use when analyzing the profiles.
   432  
   433  When 'go test' runs a test binary, it does so from within the
   434  corresponding package's source code directory. Depending on the test,
   435  it may be necessary to do the same when invoking a generated test
   436  binary directly. Because that directory may be located within the
   437  module cache, which may be read-only and is verified by checksums, the
   438  test must not write to it or any other directory within the module
   439  unless explicitly requested by the user (such as with the -fuzz flag,
   440  which writes failures to testdata/fuzz).
   441  
   442  The command-line package list, if present, must appear before any
   443  flag not known to the go test command. Continuing the example above,
   444  the package list would have to appear before -myflag, but could appear
   445  on either side of -v.
   446  
   447  When 'go test' runs in package list mode, 'go test' caches successful
   448  package test results to avoid unnecessary repeated running of tests. To
   449  disable test caching, use any test flag or argument other than the
   450  cacheable flags. The idiomatic way to disable test caching explicitly
   451  is to use -count=1.
   452  
   453  To keep an argument for a test binary from being interpreted as a
   454  known flag or a package name, use -args (see 'go help test') which
   455  passes the remainder of the command line through to the test binary
   456  uninterpreted and unaltered.
   457  
   458  For instance, the command
   459  
   460  	go test -v -args -x -v
   461  
   462  will compile the test binary and then run it as
   463  
   464  	pkg.test -test.v -x -v
   465  
   466  Similarly,
   467  
   468  	go test -args math
   469  
   470  will compile the test binary and then run it as
   471  
   472  	pkg.test math
   473  
   474  In the first example, the -x and the second -v are passed through to the
   475  test binary unchanged and with no effect on the go command itself.
   476  In the second example, the argument math is passed through to the test
   477  binary, instead of being interpreted as the package list.
   478  `,
   479  }
   480  
   481  var HelpTestfunc = &base.Command{
   482  	UsageLine: "testfunc",
   483  	Short:     "testing functions",
   484  	Long: `
   485  The 'go test' command expects to find test, benchmark, and example functions
   486  in the "*_test.go" files corresponding to the package under test.
   487  
   488  A test function is one named TestXxx (where Xxx does not start with a
   489  lower case letter) and should have the signature,
   490  
   491  	func TestXxx(t *testing.T) { ... }
   492  
   493  A benchmark function is one named BenchmarkXxx and should have the signature,
   494  
   495  	func BenchmarkXxx(b *testing.B) { ... }
   496  
   497  A fuzz test is one named FuzzXxx and should have the signature,
   498  
   499  	func FuzzXxx(f *testing.F) { ... }
   500  
   501  An example function is similar to a test function but, instead of using
   502  *testing.T to report success or failure, prints output to os.Stdout.
   503  If the last comment in the function starts with "Output:" then the output
   504  is compared exactly against the comment (see examples below). If the last
   505  comment begins with "Unordered output:" then the output is compared to the
   506  comment, however the order of the lines is ignored. An example with no such
   507  comment is compiled but not executed. An example with no text after
   508  "Output:" is compiled, executed, and expected to produce no output.
   509  
   510  Godoc displays the body of ExampleXxx to demonstrate the use
   511  of the function, constant, or variable Xxx. An example of a method M with
   512  receiver type T or *T is named ExampleT_M. There may be multiple examples
   513  for a given function, constant, or variable, distinguished by a trailing _xxx,
   514  where xxx is a suffix not beginning with an upper case letter.
   515  
   516  Here is an example of an example:
   517  
   518  	func ExamplePrintln() {
   519  		Println("The output of\nthis example.")
   520  		// Output: The output of
   521  		// this example.
   522  	}
   523  
   524  Here is another example where the ordering of the output is ignored:
   525  
   526  	func ExamplePerm() {
   527  		for _, value := range Perm(4) {
   528  			fmt.Println(value)
   529  		}
   530  
   531  		// Unordered output: 4
   532  		// 2
   533  		// 1
   534  		// 3
   535  		// 0
   536  	}
   537  
   538  The entire test file is presented as the example when it contains a single
   539  example function, at least one other function, type, variable, or constant
   540  declaration, and no tests, benchmarks, or fuzz tests.
   541  
   542  See the documentation of the testing package for more information.
   543  `,
   544  }
   545  
   546  var (
   547  	testArtifacts    bool                              // -artifacts flag
   548  	testBench        string                            // -bench flag
   549  	testC            bool                              // -c flag
   550  	testCoverPkgs    []*load.Package                   // -coverpkg flag
   551  	testCoverProfile string                            // -coverprofile flag
   552  	testFailFast     bool                              // -failfast flag
   553  	testFuzz         string                            // -fuzz flag
   554  	testJSON         bool                              // -json flag
   555  	testList         string                            // -list flag
   556  	testO            string                            // -o flag
   557  	testOutputDir    outputdirFlag                     // -outputdir flag
   558  	testShuffle      shuffleFlag                       // -shuffle flag
   559  	testTimeout      time.Duration                     // -timeout flag
   560  	testV            testVFlag                         // -v flag
   561  	testVet          = vetFlag{flags: defaultVetFlags} // -vet flag
   562  )
   563  
   564  type testVFlag struct {
   565  	on   bool // -v is set in some form
   566  	json bool // -v=test2json is set, to make output better for test2json
   567  }
   568  
   569  func (*testVFlag) IsBoolFlag() bool { return true }
   570  
   571  func (f *testVFlag) Set(arg string) error {
   572  	if v, err := strconv.ParseBool(arg); err == nil {
   573  		f.on = v
   574  		f.json = false
   575  		return nil
   576  	}
   577  	if arg == "test2json" {
   578  		f.on = true
   579  		f.json = true
   580  		return nil
   581  	}
   582  	return fmt.Errorf("invalid flag -test.v=%s", arg)
   583  }
   584  
   585  func (f *testVFlag) String() string {
   586  	if f.json {
   587  		return "test2json"
   588  	}
   589  	if f.on {
   590  		return "true"
   591  	}
   592  	return "false"
   593  }
   594  
   595  var (
   596  	testArgs []string
   597  	pkgArgs  []string
   598  	pkgs     []*load.Package
   599  
   600  	testHelp bool // -help option passed to test via -args
   601  
   602  	testKillTimeout    = 100 * 365 * 24 * time.Hour // backup alarm; defaults to about a century if no timeout is set
   603  	testWaitDelay      time.Duration                // how long to wait for output to close after a test binary exits; zero means unlimited
   604  	testCacheExpire    time.Time                    // ignore cached test results before this time
   605  	testShouldFailFast atomic.Bool                  // signals pending tests to fail fast
   606  
   607  	testBlockProfile, testCPUProfile, testMemProfile, testMutexProfile, testTrace string // profiling flag that limits test to one package
   608  
   609  	testODir = false
   610  )
   611  
   612  // testProfile returns the name of an arbitrary single-package profiling flag
   613  // that is set, if any.
   614  func testProfile() string {
   615  	switch {
   616  	case testBlockProfile != "":
   617  		return "-blockprofile"
   618  	case testCPUProfile != "":
   619  		return "-cpuprofile"
   620  	case testMemProfile != "":
   621  		return "-memprofile"
   622  	case testMutexProfile != "":
   623  		return "-mutexprofile"
   624  	case testTrace != "":
   625  		return "-trace"
   626  	default:
   627  		return ""
   628  	}
   629  }
   630  
   631  // testNeedBinary reports whether the test needs to keep the binary around.
   632  func testNeedBinary() bool {
   633  	switch {
   634  	case testBlockProfile != "":
   635  		return true
   636  	case testCPUProfile != "":
   637  		return true
   638  	case testMemProfile != "":
   639  		return true
   640  	case testMutexProfile != "":
   641  		return true
   642  	case testO != "":
   643  		return true
   644  	default:
   645  		return false
   646  	}
   647  }
   648  
   649  // testShowPass reports whether the output for a passing test should be shown.
   650  func testShowPass() bool {
   651  	return testV.on || testList != "" || testHelp
   652  }
   653  
   654  var defaultVetFlags = []string{
   655  	// TODO(rsc): Decide which tests are enabled by default.
   656  	// See golang.org/issue/18085.
   657  	// "-asmdecl",
   658  	// "-assign",
   659  	"-atomic",
   660  	"-bool",
   661  	"-buildtags",
   662  	// "-cgocall",
   663  	// "-composites",
   664  	// "-copylocks",
   665  	"-directive",
   666  	"-errorsas",
   667  	// "-httpresponse",
   668  	"-ifaceassert",
   669  	// "-lostcancel",
   670  	// "-methods",
   671  	"-nilfunc",
   672  	"-printf",
   673  	// "-rangeloops",
   674  	// "-shift",
   675  	"-slog",
   676  	"-stringintconv",
   677  	// "-structtags",
   678  	"-tests",
   679  	// "-unreachable",
   680  	// "-unsafeptr",
   681  	// "-unusedresult",
   682  }
   683  
   684  func runTest(ctx context.Context, cmd *base.Command, args []string) {
   685  	moduleLoaderState := modload.NewState()
   686  	pkgArgs, testArgs = testFlags(args)
   687  	moduleLoaderState.InitWorkfile() // The test command does custom flag processing; initialize workspaces after that.
   688  
   689  	if cfg.DebugTrace != "" {
   690  		var close func() error
   691  		var err error
   692  		ctx, close, err = trace.Start(ctx, cfg.DebugTrace)
   693  		if err != nil {
   694  			base.Fatalf("failed to start trace: %v", err)
   695  		}
   696  		defer func() {
   697  			if err := close(); err != nil {
   698  				base.Fatalf("failed to stop trace: %v", err)
   699  			}
   700  		}()
   701  	}
   702  
   703  	ctx, span := trace.StartSpan(ctx, fmt.Sprint("Running ", cmd.Name(), " command"))
   704  	defer span.Done()
   705  
   706  	work.FindExecCmd() // initialize cached result
   707  
   708  	work.BuildInit(moduleLoaderState)
   709  	work.VetFlags = testVet.flags
   710  	work.VetExplicit = testVet.explicit
   711  	work.VetTool = base.Tool("vet")
   712  
   713  	pkgOpts := load.PackageOpts{ModResolveTests: true}
   714  	pkgs = load.PackagesAndErrors(moduleLoaderState, ctx, pkgOpts, pkgArgs)
   715  	// We *don't* call load.CheckPackageErrors here because we want to report
   716  	// loading errors as per-package test setup errors later.
   717  	if len(pkgs) == 0 {
   718  		base.Fatalf("no packages to test")
   719  	}
   720  
   721  	if testFuzz != "" {
   722  		if !platform.FuzzSupported(cfg.Goos, cfg.Goarch) {
   723  			base.Fatalf("-fuzz flag is not supported on %s/%s", cfg.Goos, cfg.Goarch)
   724  		}
   725  		if len(pkgs) != 1 {
   726  			base.Fatalf("cannot use -fuzz flag with multiple packages")
   727  		}
   728  		if testCoverProfile != "" {
   729  			base.Fatalf("cannot use -coverprofile flag with -fuzz flag")
   730  		}
   731  		if profileFlag := testProfile(); profileFlag != "" {
   732  			base.Fatalf("cannot use %s flag with -fuzz flag", profileFlag)
   733  		}
   734  
   735  		// Reject the '-fuzz' flag if the package is outside the main module.
   736  		// Otherwise, if fuzzing identifies a failure it could corrupt checksums in
   737  		// the module cache (or permanently alter the behavior of std tests for all
   738  		// users) by writing the failing input to the package's testdata directory.
   739  		// (See https://golang.org/issue/48495 and cmd/internal/fuzztest/test_fuzz_modcache.txt.)
   740  		mainMods := moduleLoaderState.MainModules
   741  		if m := pkgs[0].Module; m != nil && m.Path != "" {
   742  			if !mainMods.Contains(m.Path) {
   743  				base.Fatalf("cannot use -fuzz flag on package outside the main module")
   744  			}
   745  		} else if pkgs[0].Standard && moduleLoaderState.Enabled() {
   746  			// Because packages in 'std' and 'cmd' are part of the standard library,
   747  			// they are only treated as part of a module in 'go mod' subcommands and
   748  			// 'go get'. However, we still don't want to accidentally corrupt their
   749  			// testdata during fuzzing, nor do we want to fail with surprising errors
   750  			// if GOROOT isn't writable (as is often the case for Go toolchains
   751  			// installed through package managers).
   752  			//
   753  			// If the user is requesting to fuzz a standard-library package, ensure
   754  			// that they are in the same module as that package (just like when
   755  			// fuzzing any other package).
   756  			if strings.HasPrefix(pkgs[0].ImportPath, "cmd/") {
   757  				if !mainMods.Contains("cmd") || !mainMods.InGorootSrc(module.Version{Path: "cmd"}) {
   758  					base.Fatalf("cannot use -fuzz flag on package outside the main module")
   759  				}
   760  			} else {
   761  				if !mainMods.Contains("std") || !mainMods.InGorootSrc(module.Version{Path: "std"}) {
   762  					base.Fatalf("cannot use -fuzz flag on package outside the main module")
   763  				}
   764  			}
   765  		}
   766  	}
   767  	if testProfile() != "" && len(pkgs) != 1 {
   768  		base.Fatalf("cannot use %s flag with multiple packages", testProfile())
   769  	}
   770  
   771  	if testO != "" {
   772  		if strings.HasSuffix(testO, "/") || strings.HasSuffix(testO, string(os.PathSeparator)) {
   773  			testODir = true
   774  		} else if fi, err := os.Stat(testO); err == nil && fi.IsDir() {
   775  			testODir = true
   776  		}
   777  	}
   778  
   779  	if len(pkgs) > 1 && (testC || testO != "") && !base.IsNull(testO) {
   780  		if testO != "" && !testODir {
   781  			base.Fatalf("with multiple packages, -o must refer to a directory or %s", os.DevNull)
   782  		}
   783  
   784  		pkgsForBinary := map[string][]*load.Package{}
   785  
   786  		for _, p := range pkgs {
   787  			testBinary := testBinaryName(p)
   788  			pkgsForBinary[testBinary] = append(pkgsForBinary[testBinary], p)
   789  		}
   790  
   791  		for testBinary, pkgs := range pkgsForBinary {
   792  			if len(pkgs) > 1 {
   793  				var buf strings.Builder
   794  				for _, pkg := range pkgs {
   795  					buf.WriteString(pkg.ImportPath)
   796  					buf.WriteString("\n")
   797  				}
   798  
   799  				base.Errorf("cannot write test binary %s for multiple packages:\n%s", testBinary, buf.String())
   800  			}
   801  		}
   802  
   803  		base.ExitIfErrors()
   804  	}
   805  
   806  	initCoverProfile()
   807  	defer closeCoverProfile()
   808  
   809  	// If a test timeout is finite, set our kill timeout
   810  	// to that timeout plus one minute. This is a backup alarm in case
   811  	// the test wedges with a goroutine spinning and its background
   812  	// timer does not get a chance to fire.
   813  	// Don't set this if fuzzing or benchmarking, since it should be able to run
   814  	// indefinitely.
   815  	if testTimeout > 0 && testFuzz == "" && testBench == "" {
   816  		// The WaitDelay for the test process depends on both the OS I/O and
   817  		// scheduling overhead and the amount of I/O generated by the test just
   818  		// before it exits. We set the minimum at 5 seconds to account for the OS
   819  		// overhead, and scale it up from there proportional to the overall test
   820  		// timeout on the assumption that the time to write and read a goroutine
   821  		// dump from a timed-out test process scales roughly with the overall
   822  		// running time of the test.
   823  		//
   824  		// This is probably too generous when the timeout is very long, but it seems
   825  		// better to hard-code a scale factor than to hard-code a constant delay.
   826  		if wd := testTimeout / 10; wd < 5*time.Second {
   827  			testWaitDelay = 5 * time.Second
   828  		} else {
   829  			testWaitDelay = wd
   830  		}
   831  
   832  		// We expect the test binary to terminate itself (and dump stacks) after
   833  		// exactly testTimeout. We give it up to one WaitDelay or one minute,
   834  		// whichever is longer, to finish dumping stacks before we send it an
   835  		// external signal: if the process has a lot of goroutines, dumping stacks
   836  		// after the timeout can take a while.
   837  		//
   838  		// After the signal is delivered, the test process may have up to one
   839  		// additional WaitDelay to finish writing its output streams.
   840  		if testWaitDelay < 1*time.Minute {
   841  			testKillTimeout = testTimeout + 1*time.Minute
   842  		} else {
   843  			testKillTimeout = testTimeout + testWaitDelay
   844  		}
   845  	}
   846  
   847  	// Read testcache expiration time, if present.
   848  	// (We implement go clean -testcache by writing an expiration date
   849  	// instead of searching out and deleting test result cache entries.)
   850  	if dir, _, _ := cache.DefaultDir(); dir != "off" {
   851  		if data, _ := lockedfile.Read(filepath.Join(dir, "testexpire.txt")); len(data) > 0 && data[len(data)-1] == '\n' {
   852  			if t, err := strconv.ParseInt(string(data[:len(data)-1]), 10, 64); err == nil {
   853  				testCacheExpire = time.Unix(0, t)
   854  			}
   855  		}
   856  	}
   857  
   858  	b := work.NewBuilder("", moduleLoaderState.VendorDirOrEmpty)
   859  	defer func() {
   860  		if err := b.Close(); err != nil {
   861  			base.Fatal(err)
   862  		}
   863  	}()
   864  
   865  	var builds, runs, prints []*work.Action
   866  	var writeCoverMetaAct *work.Action
   867  
   868  	if cfg.BuildCoverPkg != nil {
   869  		match := make([]func(*modload.State, *load.Package) bool, len(cfg.BuildCoverPkg))
   870  		for i := range cfg.BuildCoverPkg {
   871  			match[i] = load.MatchPackage(cfg.BuildCoverPkg[i], base.Cwd())
   872  		}
   873  
   874  		// Select for coverage all dependencies matching the -coverpkg
   875  		// patterns.
   876  		plist := load.TestPackageList(moduleLoaderState, ctx, pkgOpts, pkgs)
   877  		testCoverPkgs = load.SelectCoverPackages(moduleLoaderState, plist, match, "test")
   878  		if len(testCoverPkgs) > 0 {
   879  			// create a new singleton action that will collect up the
   880  			// meta-data files from all of the packages mentioned in
   881  			// "-coverpkg" and write them to a summary file. This new
   882  			// action will depend on all the build actions for the
   883  			// test packages, and all the run actions for these
   884  			// packages will depend on it. Motivating example:
   885  			// supposed we have a top level directory with three
   886  			// package subdirs, "a", "b", and "c", and
   887  			// from the top level, a user runs "go test -coverpkg=./... ./...".
   888  			// This will result in (roughly) the following action graph:
   889  			//
   890  			//	build("a")       build("b")         build("c")
   891  			//	    |               |                   |
   892  			//	link("a.test")   link("b.test")     link("c.test")
   893  			//	    |               |                   |
   894  			//	run("a.test")    run("b.test")      run("c.test")
   895  			//	    |               |                   |
   896  			//	  print          print              print
   897  			//
   898  			// When -coverpkg=<pattern> is in effect, we want to
   899  			// express the coverage percentage for each package as a
   900  			// fraction of *all* the statements that match the
   901  			// pattern, hence if "c" doesn't import "a", we need to
   902  			// pass as meta-data file for "a" (emitted during the
   903  			// package "a" build) to the package "c" run action, so
   904  			// that it can be incorporated with "c"'s regular
   905  			// metadata. To do this, we add edges from each compile
   906  			// action to a "writeCoverMeta" action, then from the
   907  			// writeCoverMeta action to each run action. Updated
   908  			// graph:
   909  			//
   910  			//	build("a")       build("b")         build("c")
   911  			//	    |   \       /   |               /   |
   912  			//	    |    v     v    |              /    |
   913  			//	    |   writemeta <-|-------------+     |
   914  			//	    |         |||   |                   |
   915  			//	    |         ||\   |                   |
   916  			//	link("a.test")/\ \  link("b.test")      link("c.test")
   917  			//	    |        /  \ +-|--------------+    |
   918  			//	    |       /    \  |               \   |
   919  			//	    |      v      v |                v  |
   920  			//	run("a.test")    run("b.test")      run("c.test")
   921  			//	    |               |                   |
   922  			//	  print          print              print
   923  			//
   924  			writeCoverMetaAct = &work.Action{
   925  				Mode:   "write coverage meta-data file",
   926  				Actor:  work.ActorFunc(work.WriteCoverMetaFilesFile),
   927  				Objdir: b.NewObjdir(),
   928  			}
   929  			for _, p := range testCoverPkgs {
   930  				p.Internal.Cover.GenMeta = true
   931  			}
   932  		}
   933  	}
   934  
   935  	// Inform the compiler that it should instrument the binary at
   936  	// build-time when fuzzing is enabled.
   937  	if testFuzz != "" {
   938  		// Don't instrument packages which may affect coverage guidance but are
   939  		// unlikely to be useful. Most of these are used by the testing or
   940  		// internal/fuzz packages concurrently with fuzzing.
   941  		var skipInstrumentation = map[string]bool{
   942  			"context":               true,
   943  			"internal/fuzz":         true,
   944  			"internal/godebug":      true,
   945  			"internal/runtime/maps": true,
   946  			"internal/sync":         true,
   947  			"reflect":               true,
   948  			"runtime":               true,
   949  			"sync":                  true,
   950  			"sync/atomic":           true,
   951  			"syscall":               true,
   952  			"testing":               true,
   953  			"time":                  true,
   954  		}
   955  		for _, p := range load.TestPackageList(moduleLoaderState, ctx, pkgOpts, pkgs) {
   956  			if !skipInstrumentation[p.ImportPath] {
   957  				p.Internal.FuzzInstrument = true
   958  			}
   959  		}
   960  	}
   961  
   962  	// Collect all the packages imported by the packages being tested.
   963  	allImports := make(map[*load.Package]bool)
   964  	for _, p := range pkgs {
   965  		if p.Error != nil && p.Error.IsImportCycle {
   966  			continue
   967  		}
   968  		for _, p1 := range p.Internal.Imports {
   969  			allImports[p1] = true
   970  		}
   971  	}
   972  
   973  	if cfg.BuildCover {
   974  		for _, p := range pkgs {
   975  			// sync/atomic import is inserted by the cover tool if
   976  			// we're using atomic mode (and not compiling
   977  			// sync/atomic package itself). See #18486 and #57445.
   978  			// Note that this needs to be done prior to any of the
   979  			// builderTest invocations below, due to the fact that
   980  			// a given package in the 'pkgs' list may import
   981  			// package Q which appears later in the list (if this
   982  			// happens we'll wind up building the Q compile action
   983  			// before updating its deps to include sync/atomic).
   984  			if cfg.BuildCoverMode == "atomic" && p.ImportPath != "sync/atomic" {
   985  				load.EnsureImport(moduleLoaderState, p, "sync/atomic")
   986  			}
   987  			// Tag the package for static meta-data generation if no
   988  			// test files (this works only with the new coverage
   989  			// design). Do this here (as opposed to in builderTest) so
   990  			// as to handle the case where we're testing multiple
   991  			// packages and one of the earlier packages imports a
   992  			// later package. Note that if -coverpkg is in effect
   993  			// p.Internal.Cover.GenMeta will wind up being set for
   994  			// all matching packages.
   995  			if len(p.TestGoFiles)+len(p.XTestGoFiles) == 0 && cfg.BuildCoverPkg == nil {
   996  				p.Internal.Cover.GenMeta = true
   997  			}
   998  
   999  			// Set coverage mode before building actions because it needs to be set
  1000  			// before the first package build action for the package under test is
  1001  			// created and cached, so that we can create the coverage action for it.
  1002  			if cfg.BuildCover {
  1003  				if p.Internal.Cover.GenMeta {
  1004  					p.Internal.Cover.Mode = cfg.BuildCoverMode
  1005  				}
  1006  			}
  1007  		}
  1008  	}
  1009  
  1010  	// Prepare build + run + print actions for all packages being tested.
  1011  	for _, p := range pkgs {
  1012  		reportErr := func(perr *load.Package, err error) {
  1013  			str := err.Error()
  1014  			if p.ImportPath != "" {
  1015  				load.DefaultPrinter().Errorf(perr, "# %s\n%s", p.ImportPath, str)
  1016  			} else {
  1017  				load.DefaultPrinter().Errorf(perr, "%s", str)
  1018  			}
  1019  		}
  1020  		reportSetupFailed := func(perr *load.Package, err error) {
  1021  			var stdout io.Writer = os.Stdout
  1022  			if testJSON {
  1023  				json := test2json.NewConverter(stdout, p.ImportPath, test2json.Timestamp)
  1024  				defer func() {
  1025  					json.Exited(err)
  1026  					json.Close()
  1027  				}()
  1028  				if gotestjsonbuildtext.Value() == "1" {
  1029  					// While this flag is about go build -json, the other effect
  1030  					// of that change was to include "FailedBuild" in the test JSON.
  1031  					gotestjsonbuildtext.IncNonDefault()
  1032  				} else {
  1033  					json.SetFailedBuild(perr.Desc())
  1034  				}
  1035  				stdout = json
  1036  			}
  1037  			fmt.Fprintf(stdout, "FAIL\t%s [setup failed]\n", p.ImportPath)
  1038  			base.SetExitStatus(1)
  1039  		}
  1040  
  1041  		var firstErrPkg *load.Package // arbitrarily report setup failed error for first error pkg reached in DFS
  1042  		load.PackageErrors([]*load.Package{p}, func(p *load.Package) {
  1043  			reportErr(p, p.Error)
  1044  			if firstErrPkg == nil {
  1045  				firstErrPkg = p
  1046  			}
  1047  		})
  1048  		if firstErrPkg != nil {
  1049  			reportSetupFailed(firstErrPkg, firstErrPkg.Error)
  1050  			continue
  1051  		}
  1052  		buildTest, runTest, printTest, perr, err := builderTest(moduleLoaderState, b, ctx, pkgOpts, p, allImports[p], writeCoverMetaAct)
  1053  		if err != nil {
  1054  			reportErr(perr, err)
  1055  			reportSetupFailed(perr, err)
  1056  			continue
  1057  		}
  1058  		builds = append(builds, buildTest)
  1059  		runs = append(runs, runTest)
  1060  		prints = append(prints, printTest)
  1061  	}
  1062  
  1063  	// Order runs for coordinating start JSON prints via two mechanisms:
  1064  	// 1. Channel locking forces runTest actions to start in-order.
  1065  	// 2. Barrier tasks force runTest actions to be scheduled in-order.
  1066  	// We need both for performant behavior, as channel locking without the barrier tasks starves the worker pool,
  1067  	// and barrier tasks without channel locking doesn't guarantee start in-order behavior alone.
  1068  	var prevBarrier *work.Action
  1069  	ch := make(chan struct{})
  1070  	close(ch)
  1071  	for _, a := range runs {
  1072  		if r, ok := a.Actor.(*runTestActor); ok {
  1073  			// Inject a barrier task between the run action and its dependencies.
  1074  			// This barrier task wil also depend on the previous barrier task.
  1075  			// This prevents the run task from being scheduled until all previous run dependencies have finished.
  1076  			// The build graph will be augmented to look roughly like this:
  1077  			//	build("a")           build("b")           build("c")
  1078  			//	    |                   |                     |
  1079  			//	barrier("a.test") -> barrier("b.test") -> barrier("c.test")
  1080  			//	    |                   |                     |
  1081  			//	run("a.test")        run("b.test")        run("c.test")
  1082  
  1083  			barrier := &work.Action{
  1084  				Mode: "test barrier",
  1085  				Deps: slices.Clip(a.Deps),
  1086  			}
  1087  			if prevBarrier != nil {
  1088  				barrier.Deps = append(barrier.Deps, prevBarrier)
  1089  			}
  1090  			a.Deps = []*work.Action{barrier}
  1091  			prevBarrier = barrier
  1092  
  1093  			r.prev = ch
  1094  			ch = make(chan struct{})
  1095  			r.next = ch
  1096  		}
  1097  	}
  1098  
  1099  	// Ultimately the goal is to print the output.
  1100  	root := &work.Action{Mode: "go test", Actor: work.ActorFunc(printExitStatus), Deps: prints}
  1101  
  1102  	// Force the printing of results to happen in order,
  1103  	// one at a time.
  1104  	for i, a := range prints {
  1105  		if i > 0 {
  1106  			a.Deps = append(a.Deps, prints[i-1])
  1107  		}
  1108  	}
  1109  
  1110  	// Force benchmarks to run in serial.
  1111  	if !testC && (testBench != "") {
  1112  		// The first run must wait for all builds.
  1113  		// Later runs must wait for the previous run's print.
  1114  		for i, run := range runs {
  1115  			if i == 0 {
  1116  				run.Deps = append(run.Deps, builds...)
  1117  			} else {
  1118  				run.Deps = append(run.Deps, prints[i-1])
  1119  			}
  1120  		}
  1121  	}
  1122  
  1123  	b.Do(ctx, root)
  1124  }
  1125  
  1126  var windowsBadWords = []string{
  1127  	"install",
  1128  	"patch",
  1129  	"setup",
  1130  	"update",
  1131  }
  1132  
  1133  func builderTest(loaderstate *modload.State, b *work.Builder, ctx context.Context, pkgOpts load.PackageOpts, p *load.Package, imported bool, writeCoverMetaAct *work.Action) (buildAction, runAction, printAction *work.Action, perr *load.Package, err error) {
  1134  	if len(p.TestGoFiles)+len(p.XTestGoFiles) == 0 {
  1135  		build := b.CompileAction(work.ModeBuild, work.ModeBuild, p)
  1136  		run := &work.Action{
  1137  			Mode:       "test run",
  1138  			Actor:      new(runTestActor),
  1139  			Deps:       []*work.Action{build},
  1140  			Objdir:     b.NewObjdir(),
  1141  			Package:    p,
  1142  			IgnoreFail: true, // run (prepare output) even if build failed
  1143  		}
  1144  		if writeCoverMetaAct != nil && build.Actor != nil {
  1145  			// There is no real "run" for this package (since there
  1146  			// are no tests), but if coverage is turned on, we can
  1147  			// collect coverage data for the code in the package by
  1148  			// asking cmd/cover for a static meta-data file as part of
  1149  			// the package build. This static meta-data file is then
  1150  			// consumed by a pseudo-action (writeCoverMetaAct) that
  1151  			// adds it to a summary file, then this summary file is
  1152  			// consumed by the various "run test" actions. Below we
  1153  			// add a dependence edge between the build action and the
  1154  			// "write meta files" pseudo-action, and then another dep
  1155  			// from writeCoverMetaAct to the run action. See the
  1156  			// comment in runTest() at the definition of
  1157  			// writeCoverMetaAct for more details.
  1158  			run.Deps = append(run.Deps, writeCoverMetaAct)
  1159  			writeCoverMetaAct.Deps = append(writeCoverMetaAct.Deps, build)
  1160  		}
  1161  		addTestVet(loaderstate, b, p, run, nil)
  1162  		print := &work.Action{
  1163  			Mode:       "test print",
  1164  			Actor:      work.ActorFunc(builderPrintTest),
  1165  			Deps:       []*work.Action{run},
  1166  			Package:    p,
  1167  			IgnoreFail: true, // print even if test failed
  1168  		}
  1169  		return build, run, print, nil, nil
  1170  	}
  1171  
  1172  	// Build Package structs describing:
  1173  	//	pmain - pkg.test binary
  1174  	//	ptest - package + test files
  1175  	//	pxtest - package of external test files
  1176  	var cover *load.TestCover
  1177  	if cfg.BuildCover {
  1178  		cover = &load.TestCover{
  1179  			Mode:  cfg.BuildCoverMode,
  1180  			Local: cfg.BuildCoverPkg == nil,
  1181  			Pkgs:  testCoverPkgs,
  1182  			Paths: cfg.BuildCoverPkg,
  1183  		}
  1184  	}
  1185  	pmain, ptest, pxtest, perr := load.TestPackagesFor(loaderstate, ctx, pkgOpts, p, cover)
  1186  	if perr != nil {
  1187  		return nil, nil, nil, perr, perr.Error
  1188  	}
  1189  
  1190  	// If imported is true then this package is imported by some
  1191  	// package being tested. Make building the test version of the
  1192  	// package depend on building the non-test version, so that we
  1193  	// only report build errors once. Issue #44624.
  1194  	if imported && ptest != p {
  1195  		buildTest := b.CompileAction(work.ModeBuild, work.ModeBuild, ptest)
  1196  		buildP := b.CompileAction(work.ModeBuild, work.ModeBuild, p)
  1197  		buildTest.Deps = append(buildTest.Deps, buildP)
  1198  	}
  1199  
  1200  	testBinary := testBinaryName(p)
  1201  
  1202  	// Set testdir to compile action's objdir.
  1203  	// so that the default file path stripping applies to _testmain.go.
  1204  	testDir := b.CompileAction(work.ModeBuild, work.ModeBuild, pmain).Objdir
  1205  	if err := b.BackgroundShell().Mkdir(testDir); err != nil {
  1206  		return nil, nil, nil, nil, err
  1207  	}
  1208  
  1209  	pmain.Dir = testDir
  1210  	pmain.Internal.OmitDebug = !testC && !testNeedBinary()
  1211  	if pmain.ImportPath == "runtime.test" {
  1212  		// The runtime package needs a symbolized binary for its tests.
  1213  		// See runtime/unsafepoint_test.go.
  1214  		pmain.Internal.OmitDebug = false
  1215  	}
  1216  
  1217  	if !cfg.BuildN {
  1218  		// writeTestmain writes _testmain.go,
  1219  		// using the test description gathered in t.
  1220  		if err := os.WriteFile(testDir+"_testmain.go", *pmain.Internal.TestmainGo, 0666); err != nil {
  1221  			return nil, nil, nil, nil, err
  1222  		}
  1223  	}
  1224  
  1225  	a := b.LinkAction(loaderstate, work.ModeBuild, work.ModeBuild, pmain)
  1226  	a.Target = testDir + testBinary + cfg.ExeSuffix
  1227  	if cfg.Goos == "windows" {
  1228  		// There are many reserved words on Windows that,
  1229  		// if used in the name of an executable, cause Windows
  1230  		// to try to ask for extra permissions.
  1231  		// The word list includes setup, install, update, and patch,
  1232  		// but it does not appear to be defined anywhere.
  1233  		// We have run into this trying to run the
  1234  		// go.codereview/patch tests.
  1235  		// For package names containing those words, use test.test.exe
  1236  		// instead of pkgname.test.exe.
  1237  		// Note that this file name is only used in the Go command's
  1238  		// temporary directory. If the -c or other flags are
  1239  		// given, the code below will still use pkgname.test.exe.
  1240  		// There are two user-visible effects of this change.
  1241  		// First, you can actually run 'go test' in directories that
  1242  		// have names that Windows thinks are installer-like,
  1243  		// without getting a dialog box asking for more permissions.
  1244  		// Second, in the Windows process listing during go test,
  1245  		// the test shows up as test.test.exe, not pkgname.test.exe.
  1246  		// That second one is a drawback, but it seems a small
  1247  		// price to pay for the test running at all.
  1248  		// If maintaining the list of bad words is too onerous,
  1249  		// we could just do this always on Windows.
  1250  		for _, bad := range windowsBadWords {
  1251  			if strings.Contains(testBinary, bad) {
  1252  				a.Target = testDir + "test.test" + cfg.ExeSuffix
  1253  				break
  1254  			}
  1255  		}
  1256  	}
  1257  	buildAction = a
  1258  	var installAction, cleanAction *work.Action
  1259  	if testC || testNeedBinary() {
  1260  		// -c or profiling flag: create action to copy binary to ./test.out.
  1261  		target := filepath.Join(base.Cwd(), testBinary+cfg.ExeSuffix)
  1262  		isNull := false
  1263  
  1264  		if testO != "" {
  1265  			target = testO
  1266  
  1267  			if testODir {
  1268  				if filepath.IsAbs(target) {
  1269  					target = filepath.Join(target, testBinary+cfg.ExeSuffix)
  1270  				} else {
  1271  					target = filepath.Join(base.Cwd(), target, testBinary+cfg.ExeSuffix)
  1272  				}
  1273  			} else {
  1274  				if base.IsNull(target) {
  1275  					isNull = true
  1276  				} else if !filepath.IsAbs(target) {
  1277  					target = filepath.Join(base.Cwd(), target)
  1278  				}
  1279  			}
  1280  		}
  1281  
  1282  		if isNull {
  1283  			runAction = buildAction
  1284  		} else {
  1285  			pmain.Target = target
  1286  			installAction = &work.Action{
  1287  				Mode:    "test build",
  1288  				Actor:   work.ActorFunc(work.BuildInstallFunc),
  1289  				Deps:    []*work.Action{buildAction},
  1290  				Package: pmain,
  1291  				Target:  target,
  1292  			}
  1293  			runAction = installAction // make sure runAction != nil even if not running test
  1294  		}
  1295  	}
  1296  
  1297  	var vetRunAction *work.Action
  1298  	if testC {
  1299  		printAction = &work.Action{Mode: "test print (nop)", Package: p, Deps: []*work.Action{runAction}} // nop
  1300  		vetRunAction = printAction
  1301  	} else {
  1302  		// run test
  1303  		rta := &runTestActor{
  1304  			writeCoverMetaAct: writeCoverMetaAct,
  1305  		}
  1306  		runAction = &work.Action{
  1307  			Mode:       "test run",
  1308  			Actor:      rta,
  1309  			Deps:       []*work.Action{buildAction},
  1310  			Package:    p,
  1311  			IgnoreFail: true, // run (prepare output) even if build failed
  1312  			TryCache:   rta.c.tryCache,
  1313  		}
  1314  		if writeCoverMetaAct != nil {
  1315  			// If writeCoverMetaAct != nil, this indicates that our
  1316  			// "go test -coverpkg" run actions will need to read the
  1317  			// meta-files summary file written by writeCoverMetaAct,
  1318  			// so add a dependence edge from writeCoverMetaAct to the
  1319  			// run action.
  1320  			runAction.Deps = append(runAction.Deps, writeCoverMetaAct)
  1321  			if !p.IsTestOnly() {
  1322  				// Package p is not test only, meaning that the build
  1323  				// action for p may generate a static meta-data file.
  1324  				// Add a dependence edge from p to writeCoverMetaAct,
  1325  				// which needs to know the name of that meta-data
  1326  				// file.
  1327  				compileAction := b.CompileAction(work.ModeBuild, work.ModeBuild, p)
  1328  				writeCoverMetaAct.Deps = append(writeCoverMetaAct.Deps, compileAction)
  1329  			}
  1330  		}
  1331  		runAction.Objdir = testDir
  1332  		vetRunAction = runAction
  1333  		cleanAction = &work.Action{
  1334  			Mode:       "test clean",
  1335  			Actor:      work.ActorFunc(builderCleanTest),
  1336  			Deps:       []*work.Action{runAction},
  1337  			Package:    p,
  1338  			IgnoreFail: true, // clean even if test failed
  1339  			Objdir:     testDir,
  1340  		}
  1341  		printAction = &work.Action{
  1342  			Mode:       "test print",
  1343  			Actor:      work.ActorFunc(builderPrintTest),
  1344  			Deps:       []*work.Action{cleanAction},
  1345  			Package:    p,
  1346  			IgnoreFail: true, // print even if test failed
  1347  		}
  1348  	}
  1349  
  1350  	if len(ptest.GoFiles)+len(ptest.CgoFiles) > 0 {
  1351  		addTestVet(loaderstate, b, ptest, vetRunAction, installAction)
  1352  	}
  1353  	if pxtest != nil {
  1354  		addTestVet(loaderstate, b, pxtest, vetRunAction, installAction)
  1355  	}
  1356  
  1357  	if installAction != nil {
  1358  		if runAction != installAction {
  1359  			installAction.Deps = append(installAction.Deps, runAction)
  1360  		}
  1361  		if cleanAction != nil {
  1362  			cleanAction.Deps = append(cleanAction.Deps, installAction)
  1363  		}
  1364  	}
  1365  
  1366  	return buildAction, runAction, printAction, nil, nil
  1367  }
  1368  
  1369  func addTestVet(loaderstate *modload.State, b *work.Builder, p *load.Package, runAction, installAction *work.Action) {
  1370  	if testVet.off {
  1371  		return
  1372  	}
  1373  
  1374  	vet := b.VetAction(loaderstate, work.ModeBuild, work.ModeBuild, false, p)
  1375  	runAction.Deps = append(runAction.Deps, vet)
  1376  	// Install will clean the build directory.
  1377  	// Make sure vet runs first.
  1378  	// The install ordering in b.VetAction does not apply here
  1379  	// because we are using a custom installAction (created above).
  1380  	if installAction != nil {
  1381  		installAction.Deps = append(installAction.Deps, vet)
  1382  	}
  1383  }
  1384  
  1385  var noTestsToRun = []byte("\ntesting: warning: no tests to run\n")
  1386  var noFuzzTestsToFuzz = []byte("\ntesting: warning: no fuzz tests to fuzz\n")
  1387  var tooManyFuzzTestsToFuzz = []byte("\ntesting: warning: -fuzz matches more than one fuzz test, won't fuzz\n")
  1388  
  1389  // runTestActor is the actor for running a test.
  1390  type runTestActor struct {
  1391  	c runCache
  1392  
  1393  	// writeCoverMetaAct points to the pseudo-action for collecting
  1394  	// coverage meta-data files for selected -cover test runs. See the
  1395  	// comment in runTest at the definition of writeCoverMetaAct for
  1396  	// more details.
  1397  	writeCoverMetaAct *work.Action
  1398  
  1399  	// sequencing of json start messages, to preserve test order
  1400  	prev <-chan struct{} // wait to start until prev is closed
  1401  	next chan<- struct{} // close next once the next test can start.
  1402  }
  1403  
  1404  // runCache is the cache for running a single test.
  1405  type runCache struct {
  1406  	disableCache bool // cache should be disabled for this run
  1407  
  1408  	buf     *bytes.Buffer
  1409  	id1     cache.ActionID
  1410  	id2     cache.ActionID
  1411  	covMeta cache.ActionID // Hash of writeCoverMetaAct dependencies, for invalidating coverage profiles
  1412  }
  1413  
  1414  func coverProfTempFile(a *work.Action) string {
  1415  	if a.Objdir == "" {
  1416  		panic("internal error: objdir not set in coverProfTempFile")
  1417  	}
  1418  	return a.Objdir + "_cover_.out"
  1419  }
  1420  
  1421  // stdoutMu and lockedStdout provide a locked standard output
  1422  // that guarantees never to interlace writes from multiple
  1423  // goroutines, so that we can have multiple JSON streams writing
  1424  // to a lockedStdout simultaneously and know that events will
  1425  // still be intelligible.
  1426  var stdoutMu sync.Mutex
  1427  
  1428  type lockedStdout struct{}
  1429  
  1430  func (lockedStdout) Write(b []byte) (int, error) {
  1431  	stdoutMu.Lock()
  1432  	defer stdoutMu.Unlock()
  1433  	return os.Stdout.Write(b)
  1434  }
  1435  
  1436  func (r *runTestActor) Act(b *work.Builder, ctx context.Context, a *work.Action) error {
  1437  	sh := b.Shell(a)
  1438  	barrierAction := a.Deps[0]
  1439  	buildAction := barrierAction.Deps[0]
  1440  
  1441  	// Wait for previous test to get started and print its first json line.
  1442  	select {
  1443  	case <-r.prev:
  1444  		// If should fail fast then release next test and exit.
  1445  		if testShouldFailFast.Load() {
  1446  			close(r.next)
  1447  			return nil
  1448  		}
  1449  	case <-base.Interrupted:
  1450  		// We can't wait for the previous test action to complete: we don't start
  1451  		// new actions after an interrupt, so if that action wasn't already running
  1452  		// it might never happen. Instead, just don't log anything for this action.
  1453  		base.SetExitStatus(1)
  1454  		return nil
  1455  	}
  1456  
  1457  	// Stream test output (no buffering) when no package has
  1458  	// been given on the command line (implicit current directory)
  1459  	// or when benchmarking or fuzzing.
  1460  	streamOutput := len(pkgArgs) == 0 || testBench != "" || testFuzz != ""
  1461  
  1462  	// If we're only running a single package under test or if parallelism is
  1463  	// set to 1, and if we're displaying all output (testShowPass), we can
  1464  	// hurry the output along, echoing it as soon as it comes in.
  1465  	// We still have to copy to &buf for caching the result. This special
  1466  	// case was introduced in Go 1.5 and is intentionally undocumented:
  1467  	// the exact details of output buffering are up to the go command and
  1468  	// subject to change. It would be nice to remove this special case
  1469  	// entirely, but it is surely very helpful to see progress being made
  1470  	// when tests are run on slow single-CPU ARM systems.
  1471  	//
  1472  	// If we're showing JSON output, then display output as soon as
  1473  	// possible even when multiple tests are being run: the JSON output
  1474  	// events are attributed to specific package tests, so interlacing them
  1475  	// is OK.
  1476  	streamAndCacheOutput := testShowPass() && (len(pkgs) == 1 || cfg.BuildP == 1) || testJSON
  1477  
  1478  	var stdout io.Writer = os.Stdout
  1479  	var err error
  1480  	var json *test2json.Converter
  1481  	if testJSON {
  1482  		json = test2json.NewConverter(lockedStdout{}, a.Package.ImportPath, test2json.Timestamp)
  1483  		defer func() {
  1484  			json.Exited(err)
  1485  			json.Close()
  1486  		}()
  1487  		stdout = json
  1488  	}
  1489  
  1490  	var buf bytes.Buffer
  1491  	if streamOutput {
  1492  		// No change to stdout.
  1493  	} else if streamAndCacheOutput {
  1494  		// Write both to stdout and buf, for possible saving
  1495  		// to cache, and for looking for the "no tests to run" message.
  1496  		stdout = io.MultiWriter(stdout, &buf)
  1497  	} else {
  1498  		stdout = &buf
  1499  	}
  1500  
  1501  	// Release next test to start (test2json.NewConverter writes the start event).
  1502  	close(r.next)
  1503  
  1504  	if a.Failed != nil {
  1505  		// We were unable to build the binary.
  1506  		if json != nil && a.Failed.Package != nil {
  1507  			if gotestjsonbuildtext.Value() == "1" {
  1508  				gotestjsonbuildtext.IncNonDefault()
  1509  			} else {
  1510  				json.SetFailedBuild(a.Failed.Package.Desc())
  1511  			}
  1512  		}
  1513  		a.Failed = nil
  1514  		fmt.Fprintf(stdout, "FAIL\t%s [build failed]\n", a.Package.ImportPath)
  1515  		// Tell the JSON converter that this was a failure, not a passing run.
  1516  		err = errors.New("build failed")
  1517  		base.SetExitStatus(1)
  1518  		if stdout == &buf {
  1519  			a.TestOutput = &buf
  1520  		}
  1521  		return nil
  1522  	}
  1523  
  1524  	if p := a.Package; len(p.TestGoFiles)+len(p.XTestGoFiles) == 0 {
  1525  		reportNoTestFiles := true
  1526  		if cfg.BuildCover && p.Internal.Cover.GenMeta {
  1527  			if err := sh.Mkdir(a.Objdir); err != nil {
  1528  				return err
  1529  			}
  1530  			mf, err := work.BuildActionCoverMetaFile(a)
  1531  			if err != nil {
  1532  				return err
  1533  			} else if mf != "" {
  1534  				reportNoTestFiles = false
  1535  				// Write out "percent statements covered".
  1536  				if err := work.WriteCoveragePercent(b, a, mf, stdout); err != nil {
  1537  					return err
  1538  				}
  1539  				// If -coverprofile is in effect, then generate a
  1540  				// coverage profile fragment for this package and
  1541  				// merge it with the final -coverprofile output file.
  1542  				if coverMerge.f != nil {
  1543  					cp := coverProfTempFile(a)
  1544  					if err := work.WriteCoverageProfile(b, a, mf, cp, stdout); err != nil {
  1545  						return err
  1546  					}
  1547  					mergeCoverProfile(cp)
  1548  				}
  1549  			}
  1550  		}
  1551  		if reportNoTestFiles {
  1552  			fmt.Fprintf(stdout, "?   \t%s\t[no test files]\n", p.ImportPath)
  1553  		}
  1554  		if stdout == &buf {
  1555  			a.TestOutput = &buf
  1556  		}
  1557  		return nil
  1558  	}
  1559  
  1560  	if r.c.buf == nil {
  1561  		// We did not find a cached result using the link step action ID,
  1562  		// so we ran the link step. Try again now with the link output
  1563  		// content ID. The attempt using the action ID makes sure that
  1564  		// if the link inputs don't change, we reuse the cached test
  1565  		// result without even rerunning the linker. The attempt using
  1566  		// the link output (test binary) content ID makes sure that if
  1567  		// we have different link inputs but the same final binary,
  1568  		// we still reuse the cached test result.
  1569  		// c.saveOutput will store the result under both IDs.
  1570  		r.c.tryCacheWithID(b, a, buildAction.BuildContentID())
  1571  	}
  1572  	if r.c.buf != nil {
  1573  		if stdout != &buf {
  1574  			stdout.Write(r.c.buf.Bytes())
  1575  			r.c.buf.Reset()
  1576  		}
  1577  		a.TestOutput = r.c.buf
  1578  		return nil
  1579  	}
  1580  
  1581  	execCmd := work.FindExecCmd()
  1582  	testlogArg := []string{}
  1583  	if !r.c.disableCache && len(execCmd) == 0 {
  1584  		testlogArg = []string{"-test.testlogfile=" + a.Objdir + "testlog.txt"}
  1585  	}
  1586  	panicArg := "-test.paniconexit0"
  1587  	fuzzArg := []string{}
  1588  	if testFuzz != "" {
  1589  		fuzzCacheDir := filepath.Join(cache.Default().FuzzDir(), a.Package.ImportPath)
  1590  		fuzzArg = []string{"-test.fuzzcachedir=" + fuzzCacheDir}
  1591  	}
  1592  	coverdirArg := []string{}
  1593  	addToEnv := ""
  1594  	if cfg.BuildCover {
  1595  		gcd := filepath.Join(a.Objdir, "gocoverdir")
  1596  		if err := sh.Mkdir(gcd); err != nil {
  1597  			// If we can't create a temp dir, terminate immediately
  1598  			// with an error as opposed to returning an error to the
  1599  			// caller; failed MkDir most likely indicates that we're
  1600  			// out of disk space or there is some other systemic error
  1601  			// that will make forward progress unlikely.
  1602  			base.Fatalf("failed to create temporary dir: %v", err)
  1603  		}
  1604  		coverdirArg = append(coverdirArg, "-test.gocoverdir="+gcd)
  1605  		if r.writeCoverMetaAct != nil {
  1606  			// Copy the meta-files file over into the test's coverdir
  1607  			// directory so that the coverage runtime support will be
  1608  			// able to find it.
  1609  			src := r.writeCoverMetaAct.Objdir + coverage.MetaFilesFileName
  1610  			dst := filepath.Join(gcd, coverage.MetaFilesFileName)
  1611  			if err := sh.CopyFile(dst, src, 0666, false); err != nil {
  1612  				return err
  1613  			}
  1614  		}
  1615  		// Even though we are passing the -test.gocoverdir option to
  1616  		// the test binary, also set GOCOVERDIR as well. This is
  1617  		// intended to help with tests that run "go build" to build
  1618  		// fresh copies of tools to test as part of the testing.
  1619  		addToEnv = "GOCOVERDIR=" + gcd
  1620  	}
  1621  	args := str.StringList(execCmd, buildAction.BuiltTarget(), testlogArg, panicArg, fuzzArg, coverdirArg, testArgs)
  1622  
  1623  	if testCoverProfile != "" {
  1624  		// Write coverage to temporary profile, for merging later.
  1625  		for i, arg := range args {
  1626  			if strings.HasPrefix(arg, "-test.coverprofile=") {
  1627  				args[i] = "-test.coverprofile=" + coverProfTempFile(a)
  1628  			}
  1629  		}
  1630  	}
  1631  
  1632  	if cfg.BuildN || cfg.BuildX {
  1633  		sh.ShowCmd("", "%s", strings.Join(args, " "))
  1634  		if cfg.BuildN {
  1635  			return nil
  1636  		}
  1637  	}
  1638  
  1639  	// Normally, the test will terminate itself when the timeout expires,
  1640  	// but add a last-ditch deadline to detect and stop wedged binaries.
  1641  	ctx, cancel := context.WithTimeout(ctx, testKillTimeout)
  1642  	defer cancel()
  1643  
  1644  	// Now we're ready to actually run the command.
  1645  	//
  1646  	// If the -o flag is set, or if at some point we change cmd/go to start
  1647  	// copying test executables into the build cache, we may run into spurious
  1648  	// ETXTBSY errors on Unix platforms (see https://go.dev/issue/22315).
  1649  	//
  1650  	// Since we know what causes those, and we know that they should resolve
  1651  	// quickly (the ETXTBSY error will resolve as soon as the subprocess
  1652  	// holding the descriptor open reaches its 'exec' call), we retry them
  1653  	// in a loop.
  1654  
  1655  	var (
  1656  		cmd            *exec.Cmd
  1657  		t0             time.Time
  1658  		cancelKilled   = false
  1659  		cancelSignaled = false
  1660  	)
  1661  	for {
  1662  		cmd = exec.CommandContext(ctx, args[0], args[1:]...)
  1663  		cmd.Dir = a.Package.Dir
  1664  
  1665  		env := slices.Clip(cfg.OrigEnv)
  1666  		env = base.AppendPATH(env)
  1667  		env = base.AppendPWD(env, cmd.Dir)
  1668  		cmd.Env = env
  1669  		if addToEnv != "" {
  1670  			cmd.Env = append(cmd.Env, addToEnv)
  1671  		}
  1672  
  1673  		cmd.Stdout = stdout
  1674  		cmd.Stderr = stdout
  1675  
  1676  		cmd.Cancel = func() error {
  1677  			if base.SignalTrace == nil {
  1678  				err := cmd.Process.Kill()
  1679  				if err == nil {
  1680  					cancelKilled = true
  1681  				}
  1682  				return err
  1683  			}
  1684  
  1685  			// Send a quit signal in the hope that the program will print
  1686  			// a stack trace and exit.
  1687  			err := cmd.Process.Signal(base.SignalTrace)
  1688  			if err == nil {
  1689  				cancelSignaled = true
  1690  			}
  1691  			return err
  1692  		}
  1693  		cmd.WaitDelay = testWaitDelay
  1694  
  1695  		base.StartSigHandlers()
  1696  		t0 = time.Now()
  1697  		err = cmd.Run()
  1698  
  1699  		if !base.IsETXTBSY(err) {
  1700  			// We didn't hit the race in #22315, so there is no reason to retry the
  1701  			// command.
  1702  			break
  1703  		}
  1704  	}
  1705  
  1706  	out := buf.Bytes()
  1707  	a.TestOutput = &buf
  1708  	t := fmt.Sprintf("%.3fs", time.Since(t0).Seconds())
  1709  
  1710  	mergeCoverProfile(coverProfTempFile(a))
  1711  
  1712  	if err == nil {
  1713  		norun := ""
  1714  		if !testShowPass() && !testJSON {
  1715  			buf.Reset()
  1716  		}
  1717  		if bytes.HasPrefix(out, noTestsToRun[1:]) || bytes.Contains(out, noTestsToRun) {
  1718  			norun = " [no tests to run]"
  1719  		}
  1720  		if bytes.HasPrefix(out, noFuzzTestsToFuzz[1:]) || bytes.Contains(out, noFuzzTestsToFuzz) {
  1721  			norun = " [no fuzz tests to fuzz]"
  1722  		}
  1723  		if bytes.HasPrefix(out, tooManyFuzzTestsToFuzz[1:]) || bytes.Contains(out, tooManyFuzzTestsToFuzz) {
  1724  			norun = "[-fuzz matches more than one fuzz test, won't fuzz]"
  1725  		}
  1726  		if len(out) > 0 && !bytes.HasSuffix(out, []byte("\n")) {
  1727  			// Ensure that the output ends with a newline before the "ok"
  1728  			// line we're about to print (https://golang.org/issue/49317).
  1729  			cmd.Stdout.Write([]byte("\n"))
  1730  		}
  1731  		fmt.Fprintf(cmd.Stdout, "ok  \t%s\t%s%s%s\n", a.Package.ImportPath, t, coveragePercentage(out), norun)
  1732  		r.c.saveOutput(a)
  1733  	} else {
  1734  		if testFailFast {
  1735  			testShouldFailFast.Store(true)
  1736  		}
  1737  
  1738  		base.SetExitStatus(1)
  1739  		if cancelSignaled {
  1740  			fmt.Fprintf(cmd.Stdout, "*** Test killed with %v: ran too long (%v).\n", base.SignalTrace, testKillTimeout)
  1741  		} else if cancelKilled {
  1742  			fmt.Fprintf(cmd.Stdout, "*** Test killed: ran too long (%v).\n", testKillTimeout)
  1743  		} else if errors.Is(err, exec.ErrWaitDelay) {
  1744  			fmt.Fprintf(cmd.Stdout, "*** Test I/O incomplete %v after exiting.\n", cmd.WaitDelay)
  1745  		}
  1746  		if ee, ok := errors.AsType[*exec.ExitError](err); !ok || !ee.Exited() || len(out) == 0 {
  1747  			// If there was no test output, print the exit status so that the reason
  1748  			// for failure is clear.
  1749  			fmt.Fprintf(cmd.Stdout, "%s\n", err)
  1750  		} else if !bytes.HasSuffix(out, []byte("\n")) {
  1751  			// Otherwise, ensure that the output ends with a newline before the FAIL
  1752  			// line we're about to print (https://golang.org/issue/49317).
  1753  			cmd.Stdout.Write([]byte("\n"))
  1754  		}
  1755  
  1756  		// NOTE(golang.org/issue/37555): test2json reports that a test passes
  1757  		// unless "FAIL" is printed at the beginning of a line. The test may not
  1758  		// actually print that if it panics, exits, or terminates abnormally,
  1759  		// so we print it here. We can't always check whether it was printed
  1760  		// because some tests need stdout to be a terminal (golang.org/issue/34791),
  1761  		// not a pipe.
  1762  		// TODO(golang.org/issue/29062): tests that exit with status 0 without
  1763  		// printing a final result should fail.
  1764  		prefix := ""
  1765  		if testJSON || testV.json {
  1766  			prefix = "\x16"
  1767  		}
  1768  		fmt.Fprintf(cmd.Stdout, "%sFAIL\t%s\t%s\n", prefix, a.Package.ImportPath, t)
  1769  	}
  1770  
  1771  	if cmd.Stdout != &buf {
  1772  		buf.Reset() // cmd.Stdout was going to os.Stdout already
  1773  	}
  1774  	return nil
  1775  }
  1776  
  1777  // tryCache is called just before the link attempt,
  1778  // to see if the test result is cached and therefore the link is unneeded.
  1779  // It reports whether the result can be satisfied from cache.
  1780  func (c *runCache) tryCache(b *work.Builder, a *work.Action, linkAction *work.Action) bool {
  1781  	return c.tryCacheWithID(b, a, linkAction.BuildActionID())
  1782  }
  1783  
  1784  func (c *runCache) tryCacheWithID(b *work.Builder, a *work.Action, id string) bool {
  1785  	if len(pkgArgs) == 0 {
  1786  		// Caching does not apply to "go test",
  1787  		// only to "go test foo" (including "go test .").
  1788  		if cache.DebugTest {
  1789  			fmt.Fprintf(os.Stderr, "testcache: caching disabled in local directory mode\n")
  1790  		}
  1791  		c.disableCache = true
  1792  		return false
  1793  	}
  1794  
  1795  	if a.Package.Root == "" {
  1796  		// Caching does not apply to tests outside of any module, GOPATH, or GOROOT.
  1797  		if cache.DebugTest {
  1798  			fmt.Fprintf(os.Stderr, "testcache: caching disabled for package outside of module root, GOPATH, or GOROOT: %s\n", a.Package.ImportPath)
  1799  		}
  1800  		c.disableCache = true
  1801  		return false
  1802  	}
  1803  
  1804  	// If we are collecting coverage for out-of-band packages (-coverpkg),
  1805  	// find the writeCoverMetaAct among the run action's dependencies and hash
  1806  	// its deps to ensure the cache invalidates when covered packages change.
  1807  	// Note: the run action's original deps may be wrapped inside a "test barrier"
  1808  	// action, so we search both a.Deps and any barrier's deps.
  1809  	if len(testCoverPkgs) != 0 {
  1810  		searchDeps := a.Deps
  1811  		for _, dep := range a.Deps {
  1812  			if dep.Mode == "test barrier" {
  1813  				searchDeps = dep.Deps
  1814  				break
  1815  			}
  1816  		}
  1817  		for _, dep := range searchDeps {
  1818  			if dep.Mode == "write coverage meta-data file" {
  1819  				h := cache.NewHash("covermeta")
  1820  				for _, metaDep := range dep.Deps {
  1821  					if aid := metaDep.BuildActionID(); aid != "" {
  1822  						fmt.Fprintf(h, "dep %s\n", aid)
  1823  					}
  1824  				}
  1825  				c.covMeta = h.Sum()
  1826  				break
  1827  			}
  1828  		}
  1829  	}
  1830  
  1831  	var cacheArgs []string
  1832  	for _, arg := range testArgs {
  1833  		i := strings.Index(arg, "=")
  1834  		if i < 0 || !strings.HasPrefix(arg, "-test.") {
  1835  			if cache.DebugTest {
  1836  				fmt.Fprintf(os.Stderr, "testcache: caching disabled for test argument: %s\n", arg)
  1837  			}
  1838  			c.disableCache = true
  1839  			return false
  1840  		}
  1841  		switch arg[:i] {
  1842  		case "-test.benchtime",
  1843  			"-test.cpu",
  1844  			"-test.list",
  1845  			"-test.parallel",
  1846  			"-test.run",
  1847  			"-test.short",
  1848  			"-test.skip",
  1849  			"-test.timeout",
  1850  			"-test.failfast",
  1851  			"-test.v",
  1852  			"-test.fullpath":
  1853  			// These are cacheable.
  1854  			// Note that this list is documented above,
  1855  			// so if you add to this list, update the docs too.
  1856  			cacheArgs = append(cacheArgs, arg)
  1857  		case "-test.coverprofile",
  1858  			"-test.outputdir":
  1859  			// These are cacheable and do not invalidate the cache when they change.
  1860  			// Note that this list is documented above,
  1861  			// so if you add to this list, update the docs too.
  1862  		default:
  1863  			// nothing else is cacheable
  1864  			if cache.DebugTest {
  1865  				fmt.Fprintf(os.Stderr, "testcache: caching disabled for test argument: %s\n", arg)
  1866  			}
  1867  			c.disableCache = true
  1868  			return false
  1869  		}
  1870  	}
  1871  
  1872  	// The test cache result fetch is a two-level lookup.
  1873  	//
  1874  	// First, we use the content hash of the test binary
  1875  	// and its command-line arguments to find the
  1876  	// list of environment variables and files consulted
  1877  	// the last time the test was run with those arguments.
  1878  	// (To avoid unnecessary links, we store this entry
  1879  	// under two hashes: id1 uses the linker inputs as a
  1880  	// proxy for the test binary, and id2 uses the actual
  1881  	// test binary. If the linker inputs are unchanged,
  1882  	// this way we avoid the link step, even though we
  1883  	// do not cache link outputs.)
  1884  	//
  1885  	// Second, we compute a hash of the values of the
  1886  	// environment variables and the content of the files
  1887  	// listed in the log from the previous run.
  1888  	// Then we look up test output using a combination of
  1889  	// the hash from the first part (testID) and the hash of the
  1890  	// test inputs (testInputsID).
  1891  	//
  1892  	// In order to store a new test result, we must redo the
  1893  	// testInputsID computation using the log from the run
  1894  	// we want to cache, and then we store that new log and
  1895  	// the new outputs.
  1896  
  1897  	h := cache.NewHash("testResult")
  1898  	fmt.Fprintf(h, "test binary %s args %q execcmd %q", id, cacheArgs, work.ExecCmd)
  1899  	testID := h.Sum()
  1900  	if c.id1 == (cache.ActionID{}) {
  1901  		c.id1 = testID
  1902  	} else {
  1903  		c.id2 = testID
  1904  	}
  1905  	if cache.DebugTest {
  1906  		fmt.Fprintf(os.Stderr, "testcache: %s: test ID %x => %x\n", a.Package.ImportPath, id, testID)
  1907  	}
  1908  
  1909  	// Load list of referenced environment variables and files
  1910  	// from last run of testID, and compute hash of that content.
  1911  	data, entry, err := cache.GetBytes(cache.Default(), testID)
  1912  	if !bytes.HasPrefix(data, testlogMagic) || data[len(data)-1] != '\n' {
  1913  		if cache.DebugTest {
  1914  			if err != nil {
  1915  				fmt.Fprintf(os.Stderr, "testcache: %s: input list not found: %v\n", a.Package.ImportPath, err)
  1916  			} else {
  1917  				fmt.Fprintf(os.Stderr, "testcache: %s: input list malformed\n", a.Package.ImportPath)
  1918  			}
  1919  		}
  1920  		return false
  1921  	}
  1922  	testInputsID, err := computeTestInputsID(a, data)
  1923  	if err != nil {
  1924  		return false
  1925  	}
  1926  	if cache.DebugTest {
  1927  		fmt.Fprintf(os.Stderr, "testcache: %s: test ID %x => input ID %x => %x\n", a.Package.ImportPath, testID, testInputsID, testAndInputKey(testID, testInputsID))
  1928  	}
  1929  
  1930  	// Parse cached result in preparation for changing run time to "(cached)".
  1931  	// If we can't parse the cached result, don't use it.
  1932  	data, entry, err = cache.GetBytes(cache.Default(), testAndInputKey(testID, testInputsID))
  1933  
  1934  	// Merge cached cover profile data to cover profile.
  1935  	if testCoverProfile != "" {
  1936  		// Specifically ignore entry as it will be the same as above.
  1937  		cpData, _, err := cache.GetFile(cache.Default(), coverProfileAndInputKey(testID, testInputsID, c.covMeta))
  1938  		if err != nil {
  1939  			if cache.DebugTest {
  1940  				fmt.Fprintf(os.Stderr, "testcache: %s: cached cover profile missing: %v\n", a.Package.ImportPath, err)
  1941  			}
  1942  			return false
  1943  		}
  1944  		mergeCoverProfile(cpData)
  1945  	} else if c.covMeta != (cache.ActionID{}) {
  1946  		// If we have a coverage metadata hash but no testCoverProfile, we're collecting
  1947  		// coverage for out-of-band packages. Check if the coverage profile cache is still
  1948  		// valid. If c.covMeta changed (meaning a covered package changed), the coverage
  1949  		// profile cache will miss and we need to re-run the test.
  1950  		_, _, err := cache.GetFile(cache.Default(), coverProfileAndInputKey(testID, testInputsID, c.covMeta))
  1951  		if err != nil {
  1952  			if cache.DebugTest {
  1953  				fmt.Fprintf(os.Stderr, "testcache: %s: coverage metadata changed, re-running test: %v\n", a.Package.ImportPath, err)
  1954  			}
  1955  			return false
  1956  		}
  1957  	}
  1958  
  1959  	if len(data) == 0 || data[len(data)-1] != '\n' {
  1960  		if cache.DebugTest {
  1961  			if err != nil {
  1962  				fmt.Fprintf(os.Stderr, "testcache: %s: test output not found: %v\n", a.Package.ImportPath, err)
  1963  			} else {
  1964  				fmt.Fprintf(os.Stderr, "testcache: %s: test output malformed\n", a.Package.ImportPath)
  1965  			}
  1966  		}
  1967  		return false
  1968  	}
  1969  	if entry.Time.Before(testCacheExpire) {
  1970  		if cache.DebugTest {
  1971  			fmt.Fprintf(os.Stderr, "testcache: %s: test output expired due to go clean -testcache\n", a.Package.ImportPath)
  1972  		}
  1973  		return false
  1974  	}
  1975  	i := bytes.LastIndexByte(data[:len(data)-1], '\n') + 1
  1976  	if !bytes.HasPrefix(data[i:], []byte("ok  \t")) {
  1977  		if cache.DebugTest {
  1978  			fmt.Fprintf(os.Stderr, "testcache: %s: test output malformed\n", a.Package.ImportPath)
  1979  		}
  1980  		return false
  1981  	}
  1982  	j := bytes.IndexByte(data[i+len("ok  \t"):], '\t')
  1983  	if j < 0 {
  1984  		if cache.DebugTest {
  1985  			fmt.Fprintf(os.Stderr, "testcache: %s: test output malformed\n", a.Package.ImportPath)
  1986  		}
  1987  		return false
  1988  	}
  1989  	j += i + len("ok  \t") + 1
  1990  
  1991  	// Committed to printing.
  1992  	c.buf = new(bytes.Buffer)
  1993  	c.buf.Write(data[:j])
  1994  	c.buf.WriteString("(cached)")
  1995  	for j < len(data) && ('0' <= data[j] && data[j] <= '9' || data[j] == '.' || data[j] == 's') {
  1996  		j++
  1997  	}
  1998  	c.buf.Write(data[j:])
  1999  	return true
  2000  }
  2001  
  2002  var errBadTestInputs = errors.New("error parsing test inputs")
  2003  var testlogMagic = []byte("# test log\n") // known to testing/internal/testdeps/deps.go
  2004  
  2005  // computeTestInputsID computes the "test inputs ID"
  2006  // (see comment in tryCacheWithID above) for the
  2007  // test log.
  2008  func computeTestInputsID(a *work.Action, testlog []byte) (cache.ActionID, error) {
  2009  	testlog = bytes.TrimPrefix(testlog, testlogMagic)
  2010  	h := cache.NewHash("testInputs")
  2011  	// The runtime always looks at GODEBUG, without telling us in the testlog.
  2012  	fmt.Fprintf(h, "env GODEBUG %x\n", hashGetenv("GODEBUG"))
  2013  	pwd := a.Package.Dir
  2014  	for _, line := range bytes.Split(testlog, []byte("\n")) {
  2015  		if len(line) == 0 {
  2016  			continue
  2017  		}
  2018  		s := string(line)
  2019  		op, name, found := strings.Cut(s, " ")
  2020  		if !found {
  2021  			if cache.DebugTest {
  2022  				fmt.Fprintf(os.Stderr, "testcache: %s: input list malformed (%q)\n", a.Package.ImportPath, line)
  2023  			}
  2024  			return cache.ActionID{}, errBadTestInputs
  2025  		}
  2026  		switch op {
  2027  		default:
  2028  			if cache.DebugTest {
  2029  				fmt.Fprintf(os.Stderr, "testcache: %s: input list malformed (%q)\n", a.Package.ImportPath, line)
  2030  			}
  2031  			return cache.ActionID{}, errBadTestInputs
  2032  		case "getenv":
  2033  			fmt.Fprintf(h, "env %s %x\n", name, hashGetenv(name))
  2034  		case "chdir":
  2035  			pwd = name // always absolute
  2036  			fmt.Fprintf(h, "chdir %s %x\n", name, hashStat(name))
  2037  		case "stat":
  2038  			if !filepath.IsAbs(name) {
  2039  				name = filepath.Join(pwd, name)
  2040  			}
  2041  			if a.Package.Root == "" || search.InDir(name, a.Package.Root) == "" {
  2042  				// Do not recheck files outside the module, GOPATH, or GOROOT root.
  2043  				break
  2044  			}
  2045  			fmt.Fprintf(h, "stat %s %x\n", name, hashStat(name))
  2046  		case "open":
  2047  			if !filepath.IsAbs(name) {
  2048  				name = filepath.Join(pwd, name)
  2049  			}
  2050  			if a.Package.Root == "" || search.InDir(name, a.Package.Root) == "" {
  2051  				// Do not recheck files outside the module, GOPATH, or GOROOT root.
  2052  				break
  2053  			}
  2054  			fh, err := hashOpen(name)
  2055  			if err != nil {
  2056  				if cache.DebugTest {
  2057  					fmt.Fprintf(os.Stderr, "testcache: %s: input file %s: %s\n", a.Package.ImportPath, name, err)
  2058  				}
  2059  				return cache.ActionID{}, err
  2060  			}
  2061  			fmt.Fprintf(h, "open %s %x\n", name, fh)
  2062  		}
  2063  	}
  2064  	sum := h.Sum()
  2065  	return sum, nil
  2066  }
  2067  
  2068  func hashGetenv(name string) cache.ActionID {
  2069  	h := cache.NewHash("getenv")
  2070  	v, ok := os.LookupEnv(name)
  2071  	if !ok {
  2072  		h.Write([]byte{0})
  2073  	} else {
  2074  		h.Write([]byte{1})
  2075  		h.Write([]byte(v))
  2076  	}
  2077  	return h.Sum()
  2078  }
  2079  
  2080  const modTimeCutoff = 2 * time.Second
  2081  
  2082  var errFileTooNew = errors.New("file used as input is too new")
  2083  
  2084  func hashOpen(name string) (cache.ActionID, error) {
  2085  	h := cache.NewHash("open")
  2086  	info, err := os.Stat(name)
  2087  	if err != nil {
  2088  		fmt.Fprintf(h, "err %v\n", err)
  2089  		return h.Sum(), nil
  2090  	}
  2091  	hashWriteStat(h, info)
  2092  	if info.IsDir() {
  2093  		files, err := os.ReadDir(name)
  2094  		if err != nil {
  2095  			fmt.Fprintf(h, "err %v\n", err)
  2096  		}
  2097  		for _, f := range files {
  2098  			fmt.Fprintf(h, "file %s ", f.Name())
  2099  			finfo, err := f.Info()
  2100  			if err != nil {
  2101  				fmt.Fprintf(h, "err %v\n", err)
  2102  			} else {
  2103  				hashWriteStat(h, finfo)
  2104  			}
  2105  		}
  2106  	} else if info.Mode().IsRegular() {
  2107  		// Because files might be very large, do not attempt
  2108  		// to hash the entirety of their content. Instead assume
  2109  		// the mtime and size recorded in hashWriteStat above
  2110  		// are good enough.
  2111  		//
  2112  		// To avoid problems for very recent files where a new
  2113  		// write might not change the mtime due to file system
  2114  		// mtime precision, reject caching if a file was read that
  2115  		// is less than modTimeCutoff old.
  2116  		if time.Since(info.ModTime()) < modTimeCutoff {
  2117  			return cache.ActionID{}, errFileTooNew
  2118  		}
  2119  	}
  2120  	return h.Sum(), nil
  2121  }
  2122  
  2123  func hashStat(name string) cache.ActionID {
  2124  	h := cache.NewHash("stat")
  2125  	if info, err := os.Stat(name); err != nil {
  2126  		fmt.Fprintf(h, "err %v\n", err)
  2127  	} else {
  2128  		hashWriteStat(h, info)
  2129  	}
  2130  	if info, err := os.Lstat(name); err != nil {
  2131  		fmt.Fprintf(h, "err %v\n", err)
  2132  	} else {
  2133  		hashWriteStat(h, info)
  2134  	}
  2135  	return h.Sum()
  2136  }
  2137  
  2138  func hashWriteStat(h io.Writer, info fs.FileInfo) {
  2139  	fmt.Fprintf(h, "stat %d %x %v %v\n", info.Size(), uint64(info.Mode()), info.ModTime(), info.IsDir())
  2140  }
  2141  
  2142  // testAndInputKey returns the actual cache key for the pair (testID, testInputsID).
  2143  func testAndInputKey(testID, testInputsID cache.ActionID) cache.ActionID {
  2144  	return cache.Subkey(testID, fmt.Sprintf("inputs:%x", testInputsID))
  2145  }
  2146  
  2147  // coverProfileAndInputKey returns the "coverprofile" cache key.
  2148  // If covMetaID is non-zero, it is included in the hash to ensure coverage profiles are invalidated
  2149  // when the coverage metadata changes (e.g., when source files in covered packages are modified).
  2150  func coverProfileAndInputKey(testID, testInputsID, covMetaID cache.ActionID) cache.ActionID {
  2151  	key := testAndInputKey(testID, testInputsID)
  2152  	if covMetaID != (cache.ActionID{}) {
  2153  		key = cache.Subkey(key, fmt.Sprintf("coverdeps:%x", covMetaID))
  2154  	}
  2155  	return cache.Subkey(key, "coverprofile")
  2156  }
  2157  
  2158  func (c *runCache) saveOutput(a *work.Action) {
  2159  	if c.id1 == (cache.ActionID{}) && c.id2 == (cache.ActionID{}) {
  2160  		return
  2161  	}
  2162  
  2163  	// See comment about two-level lookup in tryCacheWithID above.
  2164  	testlog, err := os.ReadFile(a.Objdir + "testlog.txt")
  2165  	if err != nil || !bytes.HasPrefix(testlog, testlogMagic) || testlog[len(testlog)-1] != '\n' {
  2166  		if cache.DebugTest {
  2167  			if err != nil {
  2168  				fmt.Fprintf(os.Stderr, "testcache: %s: reading testlog: %v\n", a.Package.ImportPath, err)
  2169  			} else {
  2170  				fmt.Fprintf(os.Stderr, "testcache: %s: reading testlog: malformed\n", a.Package.ImportPath)
  2171  			}
  2172  		}
  2173  		return
  2174  	}
  2175  	testInputsID, err := computeTestInputsID(a, testlog)
  2176  	if err != nil {
  2177  		return
  2178  	}
  2179  	var coverProfile []byte
  2180  	if testCoverProfile != "" {
  2181  		coverProfile, err = os.ReadFile(coverProfTempFile(a))
  2182  		if err != nil {
  2183  			if cache.DebugTest {
  2184  				fmt.Fprintf(os.Stderr, "testcache: %s: reading cover profile: %v\n", a.Package.ImportPath, err)
  2185  			}
  2186  			return
  2187  		}
  2188  	}
  2189  	if c.id1 != (cache.ActionID{}) {
  2190  		if cache.DebugTest {
  2191  			fmt.Fprintf(os.Stderr, "testcache: %s: save test ID %x => input ID %x => %x\n", a.Package.ImportPath, c.id1, testInputsID, testAndInputKey(c.id1, testInputsID))
  2192  		}
  2193  		cache.PutNoVerify(cache.Default(), c.id1, bytes.NewReader(testlog))
  2194  		cache.PutNoVerify(cache.Default(), testAndInputKey(c.id1, testInputsID), bytes.NewReader(a.TestOutput.Bytes()))
  2195  		if coverProfile != nil {
  2196  			cache.PutNoVerify(cache.Default(), coverProfileAndInputKey(c.id1, testInputsID, c.covMeta), bytes.NewReader(coverProfile))
  2197  		} else if c.covMeta != (cache.ActionID{}) {
  2198  			// Write a sentinel so the else-if branch in tryCacheWithID can verify
  2199  			// that the covMeta hash has not changed since the last run.
  2200  			cache.PutNoVerify(cache.Default(), coverProfileAndInputKey(c.id1, testInputsID, c.covMeta), bytes.NewReader(nil))
  2201  		}
  2202  	}
  2203  	if c.id2 != (cache.ActionID{}) {
  2204  		if cache.DebugTest {
  2205  			fmt.Fprintf(os.Stderr, "testcache: %s: save test ID %x => input ID %x => %x\n", a.Package.ImportPath, c.id2, testInputsID, testAndInputKey(c.id2, testInputsID))
  2206  		}
  2207  		cache.PutNoVerify(cache.Default(), c.id2, bytes.NewReader(testlog))
  2208  		cache.PutNoVerify(cache.Default(), testAndInputKey(c.id2, testInputsID), bytes.NewReader(a.TestOutput.Bytes()))
  2209  		if coverProfile != nil {
  2210  			cache.PutNoVerify(cache.Default(), coverProfileAndInputKey(c.id2, testInputsID, c.covMeta), bytes.NewReader(coverProfile))
  2211  		} else if c.covMeta != (cache.ActionID{}) {
  2212  			// Sentinel for covMeta validity; see comment in id1 block above.
  2213  			cache.PutNoVerify(cache.Default(), coverProfileAndInputKey(c.id2, testInputsID, c.covMeta), bytes.NewReader(nil))
  2214  		}
  2215  	}
  2216  }
  2217  
  2218  // coveragePercentage returns the coverage results (if enabled) for the
  2219  // test. It uncovers the data by scanning the output from the test run.
  2220  func coveragePercentage(out []byte) string {
  2221  	if !cfg.BuildCover {
  2222  		return ""
  2223  	}
  2224  	// The string looks like
  2225  	//	test coverage for encoding/binary: 79.9% of statements
  2226  	// Extract the piece from the percentage to the end of the line.
  2227  	re := regexp.MustCompile(`coverage: (.*)\n`)
  2228  	matches := re.FindSubmatch(out)
  2229  	if matches == nil {
  2230  		// Probably running "go test -cover" not "go test -cover fmt".
  2231  		// The coverage output will appear in the output directly.
  2232  		return ""
  2233  	}
  2234  	return fmt.Sprintf("\tcoverage: %s", matches[1])
  2235  }
  2236  
  2237  // builderCleanTest is the action for cleaning up after a test.
  2238  func builderCleanTest(b *work.Builder, ctx context.Context, a *work.Action) error {
  2239  	if cfg.BuildWork {
  2240  		return nil
  2241  	}
  2242  	b.Shell(a).RemoveAll(a.Objdir)
  2243  	return nil
  2244  }
  2245  
  2246  // builderPrintTest is the action for printing a test result.
  2247  func builderPrintTest(b *work.Builder, ctx context.Context, a *work.Action) error {
  2248  	run := a.Deps[0]
  2249  	if run.Mode == "test clean" {
  2250  		run = run.Deps[0]
  2251  	}
  2252  	if run.Mode != "test run" {
  2253  		base.Fatalf("internal error: cannot find test run to print")
  2254  	}
  2255  	if run.TestOutput != nil {
  2256  		os.Stdout.Write(run.TestOutput.Bytes())
  2257  		run.TestOutput = nil
  2258  	}
  2259  	return nil
  2260  }
  2261  
  2262  // printExitStatus is the action for printing the final exit status.
  2263  // If we are running multiple test targets, print a final "FAIL"
  2264  // in case a failure in an early package has already scrolled
  2265  // off of the user's terminal.
  2266  // (See https://golang.org/issue/30507#issuecomment-470593235.)
  2267  //
  2268  // In JSON mode, we need to maintain valid JSON output and
  2269  // we assume that the test output is being parsed by a tool
  2270  // anyway, so the failure will not be missed and would be
  2271  // awkward to try to wedge into the JSON stream.
  2272  //
  2273  // In fuzz mode, we only allow a single package for now
  2274  // (see CL 350156 and https://golang.org/issue/46312),
  2275  // so there is no possibility of scrolling off and no need
  2276  // to print the final status.
  2277  func printExitStatus(b *work.Builder, ctx context.Context, a *work.Action) error {
  2278  	if !testJSON && testFuzz == "" && len(pkgArgs) != 0 {
  2279  		if base.GetExitStatus() != 0 {
  2280  			fmt.Println("FAIL")
  2281  			return nil
  2282  		}
  2283  	}
  2284  	return nil
  2285  }
  2286  
  2287  // testBinaryName can be used to create name for test binary executable.
  2288  // Use last element of import path, not package name.
  2289  // They differ when package name is "main".
  2290  // But if the import path is "command-line-arguments",
  2291  // like it is during 'go run', use the package name.
  2292  func testBinaryName(p *load.Package) string {
  2293  	var elem string
  2294  	if p.ImportPath == "command-line-arguments" {
  2295  		elem = p.Name
  2296  	} else {
  2297  		elem = p.DefaultExecName()
  2298  	}
  2299  
  2300  	return elem + ".test"
  2301  }
  2302  

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