floatmarsh_test.go

     1  // Copyright 2015 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 big
     6  
     7  import (
     8  	"bytes"
     9  	"encoding/gob"
    10  	"encoding/json"
    11  	"io"
    12  	"strings"
    13  	"testing"
    14  )
    15  
    16  var floatVals = []string{
    17  	"0",
    18  	"1",
    19  	"0.1",
    20  	"2.71828",
    21  	"1234567890",
    22  	"3.14e1234",
    23  	"3.14e-1234",
    24  	"0.738957395793475734757349579759957975985497e100",
    25  	"0.73895739579347546656564656573475734957975995797598589749859834759476745986795497e100",
    26  	"inf",
    27  	"Inf",
    28  }
    29  
    30  func TestFloatGobEncoding(t *testing.T) {
    31  	var medium bytes.Buffer
    32  	enc := gob.NewEncoder(&medium)
    33  	dec := gob.NewDecoder(&medium)
    34  	for _, test := range floatVals {
    35  		for _, sign := range []string{"", "+", "-"} {
    36  			for _, prec := range []uint{0, 1, 2, 10, 53, 64, 100, 1000} {
    37  				for _, mode := range []RoundingMode{ToNearestEven, ToNearestAway, ToZero, AwayFromZero, ToNegativeInf, ToPositiveInf} {
    38  					medium.Reset() // empty buffer for each test case (in case of failures)
    39  					x := sign + test
    40  
    41  					var tx Float
    42  					_, _, err := tx.SetPrec(prec).SetMode(mode).Parse(x, 0)
    43  					if err != nil {
    44  						t.Errorf("parsing of %s (%dbits, %v) failed (invalid test case): %v", x, prec, mode, err)
    45  						continue
    46  					}
    47  
    48  					// If tx was set to prec == 0, tx.Parse(x, 0) assumes precision 64. Correct it.
    49  					if prec == 0 {
    50  						tx.SetPrec(0)
    51  					}
    52  
    53  					if err := enc.Encode(&tx); err != nil {
    54  						t.Errorf("encoding of %v (%dbits, %v) failed: %v", &tx, prec, mode, err)
    55  						continue
    56  					}
    57  
    58  					var rx Float
    59  					if err := dec.Decode(&rx); err != nil {
    60  						t.Errorf("decoding of %v (%dbits, %v) failed: %v", &tx, prec, mode, err)
    61  						continue
    62  					}
    63  
    64  					if rx.Cmp(&tx) != 0 {
    65  						t.Errorf("transmission of %s failed: got %s want %s", x, rx.String(), tx.String())
    66  						continue
    67  					}
    68  
    69  					if rx.Prec() != prec {
    70  						t.Errorf("transmission of %s's prec failed: got %d want %d", x, rx.Prec(), prec)
    71  					}
    72  
    73  					if rx.Mode() != mode {
    74  						t.Errorf("transmission of %s's mode failed: got %s want %s", x, rx.Mode(), mode)
    75  					}
    76  
    77  					if rx.Acc() != tx.Acc() {
    78  						t.Errorf("transmission of %s's accuracy failed: got %s want %s", x, rx.Acc(), tx.Acc())
    79  					}
    80  				}
    81  			}
    82  		}
    83  	}
    84  }
    85  
    86  func TestFloatCorruptGob(t *testing.T) {
    87  	var buf bytes.Buffer
    88  	tx := NewFloat(4 / 3).SetPrec(1000).SetMode(ToPositiveInf)
    89  	if err := gob.NewEncoder(&buf).Encode(tx); err != nil {
    90  		t.Fatal(err)
    91  	}
    92  	b := buf.Bytes()
    93  
    94  	var rx Float
    95  	if err := gob.NewDecoder(bytes.NewReader(b)).Decode(&rx); err != nil {
    96  		t.Fatal(err)
    97  	}
    98  
    99  	if err := gob.NewDecoder(bytes.NewReader(b[:10])).Decode(&rx); err != io.ErrUnexpectedEOF {
   100  		t.Errorf("got %v want EOF", err)
   101  	}
   102  
   103  	b[1] = 0
   104  	if err := gob.NewDecoder(bytes.NewReader(b)).Decode(&rx); err == nil {
   105  		t.Fatal("got nil want version error")
   106  	}
   107  }
   108  
   109  func TestFloatJSONEncoding(t *testing.T) {
   110  	for _, test := range floatVals {
   111  		for _, sign := range []string{"", "+", "-"} {
   112  			for _, prec := range []uint{0, 1, 2, 10, 53, 64, 100, 1000} {
   113  				if prec > 53 && testing.Short() {
   114  					continue
   115  				}
   116  				x := sign + test
   117  				var tx Float
   118  				_, _, err := tx.SetPrec(prec).Parse(x, 0)
   119  				if err != nil {
   120  					t.Errorf("parsing of %s (prec = %d) failed (invalid test case): %v", x, prec, err)
   121  					continue
   122  				}
   123  				b, err := json.Marshal(&tx)
   124  				if err != nil {
   125  					t.Errorf("marshaling of %v (prec = %d) failed: %v", &tx, prec, err)
   126  					continue
   127  				}
   128  				var rx Float
   129  				rx.SetPrec(prec)
   130  				if err := json.Unmarshal(b, &rx); err != nil {
   131  					t.Errorf("unmarshaling of %v (prec = %d) failed: %v", &tx, prec, err)
   132  					continue
   133  				}
   134  				if rx.Cmp(&tx) != 0 {
   135  					t.Errorf("JSON encoding of %v (prec = %d) failed: got %v want %v", &tx, prec, &rx, &tx)
   136  				}
   137  			}
   138  		}
   139  	}
   140  }
   141  
   142  func TestFloatGobDecodeShortBuffer(t *testing.T) {
   143  	for _, tc := range [][]byte{
   144  		[]byte{0x1, 0x0, 0x0, 0x0},
   145  		[]byte{0x1, 0xfa, 0x0, 0x0, 0x0, 0x0},
   146  	} {
   147  		err := NewFloat(0).GobDecode(tc)
   148  		if err == nil {
   149  			t.Error("expected GobDecode to return error for malformed input")
   150  		}
   151  	}
   152  }
   153  
   154  func TestFloatGobDecodeInvalid(t *testing.T) {
   155  	for _, tc := range []struct {
   156  		buf []byte
   157  		msg string
   158  	}{
   159  		{
   160  			[]byte{0x1, 0x2a, 0x20, 0x20, 0x20, 0x20, 0x0, 0x20, 0x20, 0x20, 0x0, 0x20, 0x20, 0x20, 0x20, 0x0, 0x0, 0x0, 0x0, 0xc},
   161  			"Float.GobDecode: msb not set in last word",
   162  		},
   163  		{
   164  			[]byte{1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0},
   165  			"Float.GobDecode: nonzero finite number with empty mantissa",
   166  		},
   167  	} {
   168  		err := NewFloat(0).GobDecode(tc.buf)
   169  		if err == nil || !strings.HasPrefix(err.Error(), tc.msg) {
   170  			t.Errorf("expected GobDecode error prefix: %s, got: %v", tc.msg, err)
   171  		}
   172  	}
   173  }
   174
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