panicnil_test.go

     1  // Copyright 2023 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 runtime_test
     6  
     7  import (
     8  	"reflect"
     9  	"runtime"
    10  	"runtime/metrics"
    11  	"testing"
    12  )
    13  
    14  func TestPanicNil(t *testing.T) {
    15  	t.Run("default", func(t *testing.T) {
    16  		checkPanicNil(t, new(runtime.PanicNilError))
    17  	})
    18  	t.Run("GODEBUG=panicnil=0", func(t *testing.T) {
    19  		t.Setenv("GODEBUG", "panicnil=0")
    20  		checkPanicNil(t, new(runtime.PanicNilError))
    21  	})
    22  	t.Run("GODEBUG=panicnil=1", func(t *testing.T) {
    23  		t.Setenv("GODEBUG", "panicnil=1")
    24  		checkPanicNil(t, nil)
    25  	})
    26  }
    27  
    28  func checkPanicNil(t *testing.T, want any) {
    29  	name := "/godebug/non-default-behavior/panicnil:events"
    30  	s := []metrics.Sample{{Name: name}}
    31  	metrics.Read(s)
    32  	v1 := s[0].Value.Uint64()
    33  
    34  	defer func() {
    35  		e := recover()
    36  		if reflect.TypeOf(e) != reflect.TypeOf(want) {
    37  			println(e, want)
    38  			t.Errorf("recover() = %v, want %v", e, want)
    39  			panic(e)
    40  		}
    41  		metrics.Read(s)
    42  		v2 := s[0].Value.Uint64()
    43  		if want == nil {
    44  			if v2 != v1+1 {
    45  				t.Errorf("recover() with panicnil=1 did not increment metric %s", name)
    46  			}
    47  		} else {
    48  			if v2 != v1 {
    49  				t.Errorf("recover() with panicnil=0 incremented metric %s: %d -> %d", name, v1, v2)
    50  			}
    51  		}
    52  	}()
    53  	panic(nil)
    54  }
    55
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