1 files changed, 240 insertions, 0 deletions
diff --git a/src/strconv/ftoa_test.go b/src/strconv/ftoa_test.go
new file mode 100644
index 000000000..39b861547
--- /dev/null
+++ b/src/strconv/ftoa_test.go
@@ -0,0 +1,240 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package strconv_test
+
+import (
+	"math"
+	"math/rand"
+	. "strconv"
+	"testing"
+)
+
+type ftoaTest struct {
+	f    float64
+	fmt  byte
+	prec int
+	s    string
+}
+
+func fdiv(a, b float64) float64 { return a / b } // keep compiler in the dark
+
+const (
+	below1e23 = 99999999999999974834176
+	above1e23 = 100000000000000008388608
+)
+
+var ftoatests = []ftoaTest{
+	{1, 'e', 5, "1.00000e+00"},
+	{1, 'f', 5, "1.00000"},
+	{1, 'g', 5, "1"},
+	{1, 'g', -1, "1"},
+	{20, 'g', -1, "20"},
+	{1234567.8, 'g', -1, "1.2345678e+06"},
+	{200000, 'g', -1, "200000"},
+	{2000000, 'g', -1, "2e+06"},
+
+	// g conversion and zero suppression
+	{400, 'g', 2, "4e+02"},
+	{40, 'g', 2, "40"},
+	{4, 'g', 2, "4"},
+	{.4, 'g', 2, "0.4"},
+	{.04, 'g', 2, "0.04"},
+	{.004, 'g', 2, "0.004"},
+	{.0004, 'g', 2, "0.0004"},
+	{.00004, 'g', 2, "4e-05"},
+	{.000004, 'g', 2, "4e-06"},
+
+	{0, 'e', 5, "0.00000e+00"},
+	{0, 'f', 5, "0.00000"},
+	{0, 'g', 5, "0"},
+	{0, 'g', -1, "0"},
+
+	{-1, 'e', 5, "-1.00000e+00"},
+	{-1, 'f', 5, "-1.00000"},
+	{-1, 'g', 5, "-1"},
+	{-1, 'g', -1, "-1"},
+
+	{12, 'e', 5, "1.20000e+01"},
+	{12, 'f', 5, "12.00000"},
+	{12, 'g', 5, "12"},
+	{12, 'g', -1, "12"},
+
+	{123456700, 'e', 5, "1.23457e+08"},
+	{123456700, 'f', 5, "123456700.00000"},
+	{123456700, 'g', 5, "1.2346e+08"},
+	{123456700, 'g', -1, "1.234567e+08"},
+
+	{1.2345e6, 'e', 5, "1.23450e+06"},
+	{1.2345e6, 'f', 5, "1234500.00000"},
+	{1.2345e6, 'g', 5, "1.2345e+06"},
+
+	{1e23, 'e', 17, "9.99999999999999916e+22"},
+	{1e23, 'f', 17, "99999999999999991611392.00000000000000000"},
+	{1e23, 'g', 17, "9.9999999999999992e+22"},
+
+	{1e23, 'e', -1, "1e+23"},
+	{1e23, 'f', -1, "100000000000000000000000"},
+	{1e23, 'g', -1, "1e+23"},
+
+	{below1e23, 'e', 17, "9.99999999999999748e+22"},
+	{below1e23, 'f', 17, "99999999999999974834176.00000000000000000"},
+	{below1e23, 'g', 17, "9.9999999999999975e+22"},
+
+	{below1e23, 'e', -1, "9.999999999999997e+22"},
+	{below1e23, 'f', -1, "99999999999999970000000"},
+	{below1e23, 'g', -1, "9.999999999999997e+22"},
+
+	{above1e23, 'e', 17, "1.00000000000000008e+23"},
+	{above1e23, 'f', 17, "100000000000000008388608.00000000000000000"},
+	{above1e23, 'g', 17, "1.0000000000000001e+23"},
+
+	{above1e23, 'e', -1, "1.0000000000000001e+23"},
+	{above1e23, 'f', -1, "100000000000000010000000"},
+	{above1e23, 'g', -1, "1.0000000000000001e+23"},
+
+	{fdiv(5e-304, 1e20), 'g', -1, "5e-324"},
+	{fdiv(-5e-304, 1e20), 'g', -1, "-5e-324"},
+
+	{32, 'g', -1, "32"},
+	{32, 'g', 0, "3e+01"},
+
+	{100, 'x', -1, "%x"},
+
+	{math.NaN(), 'g', -1, "NaN"},
+	{-math.NaN(), 'g', -1, "NaN"},
+	{math.Inf(0), 'g', -1, "+Inf"},
+	{math.Inf(-1), 'g', -1, "-Inf"},
+	{-math.Inf(0), 'g', -1, "-Inf"},
+
+	{-1, 'b', -1, "-4503599627370496p-52"},
+
+	// fixed bugs
+	{0.9, 'f', 1, "0.9"},
+	{0.09, 'f', 1, "0.1"},
+	{0.0999, 'f', 1, "0.1"},
+	{0.05, 'f', 1, "0.1"},
+	{0.05, 'f', 0, "0"},
+	{0.5, 'f', 1, "0.5"},
+	{0.5, 'f', 0, "0"},
+	{1.5, 'f', 0, "2"},
+
+	// http://www.exploringbinary.com/java-hangs-when-converting-2-2250738585072012e-308/
+	{2.2250738585072012e-308, 'g', -1, "2.2250738585072014e-308"},
+	// http://www.exploringbinary.com/php-hangs-on-numeric-value-2-2250738585072011e-308/
+	{2.2250738585072011e-308, 'g', -1, "2.225073858507201e-308"},
+
+	// Issue 2625.
+	{383260575764816448, 'f', 0, "383260575764816448"},
+	{383260575764816448, 'g', -1, "3.8326057576481645e+17"},
+}
+
+func TestFtoa(t *testing.T) {
+	for i := 0; i < len(ftoatests); i++ {
+		test := &ftoatests[i]
+		s := FormatFloat(test.f, test.fmt, test.prec, 64)
+		if s != test.s {
+			t.Error("testN=64", test.f, string(test.fmt), test.prec, "want", test.s, "got", s)
+		}
+		x := AppendFloat([]byte("abc"), test.f, test.fmt, test.prec, 64)
+		if string(x) != "abc"+test.s {
+			t.Error("AppendFloat testN=64", test.f, string(test.fmt), test.prec, "want", "abc"+test.s, "got", string(x))
+		}
+		if float64(float32(test.f)) == test.f && test.fmt != 'b' {
+			s := FormatFloat(test.f, test.fmt, test.prec, 32)
+			if s != test.s {
+				t.Error("testN=32", test.f, string(test.fmt), test.prec, "want", test.s, "got", s)
+			}
+			x := AppendFloat([]byte("abc"), test.f, test.fmt, test.prec, 32)
+			if string(x) != "abc"+test.s {
+				t.Error("AppendFloat testN=32", test.f, string(test.fmt), test.prec, "want", "abc"+test.s, "got", string(x))
+			}
+		}
+	}
+}
+
+func TestFtoaRandom(t *testing.T) {
+	N := int(1e4)
+	if testing.Short() {
+		N = 100
+	}
+	t.Logf("testing %d random numbers with fast and slow FormatFloat", N)
+	for i := 0; i < N; i++ {
+		bits := uint64(rand.Uint32())<<32 | uint64(rand.Uint32())
+		x := math.Float64frombits(bits)
+
+		shortFast := FormatFloat(x, 'g', -1, 64)
+		SetOptimize(false)
+		shortSlow := FormatFloat(x, 'g', -1, 64)
+		SetOptimize(true)
+		if shortSlow != shortFast {
+			t.Errorf("%b printed as %s, want %s", x, shortFast, shortSlow)
+		}
+
+		prec := rand.Intn(12) + 5
+		shortFast = FormatFloat(x, 'e', prec, 64)
+		SetOptimize(false)
+		shortSlow = FormatFloat(x, 'e', prec, 64)
+		SetOptimize(true)
+		if shortSlow != shortFast {
+			t.Errorf("%b printed as %s, want %s", x, shortFast, shortSlow)
+		}
+	}
+}
+
+func BenchmarkFormatFloatDecimal(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		FormatFloat(33909, 'g', -1, 64)
+	}
+}
+
+func BenchmarkFormatFloat(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		FormatFloat(339.7784, 'g', -1, 64)
+	}
+}
+
+func BenchmarkFormatFloatExp(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		FormatFloat(-5.09e75, 'g', -1, 64)
+	}
+}
+
+func BenchmarkFormatFloatNegExp(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		FormatFloat(-5.11e-95, 'g', -1, 64)
+	}
+}
+
+func BenchmarkFormatFloatBig(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		FormatFloat(123456789123456789123456789, 'g', -1, 64)
+	}
+}
+
+func benchmarkAppendFloat(b *testing.B, f float64, fmt byte, prec, bitSize int) {
+	dst := make([]byte, 30)
+	for i := 0; i < b.N; i++ {
+		AppendFloat(dst[:0], f, fmt, prec, bitSize)
+	}
+}
+
+func BenchmarkAppendFloatDecimal(b *testing.B) { benchmarkAppendFloat(b, 33909, 'g', -1, 64) }
+func BenchmarkAppendFloat(b *testing.B)        { benchmarkAppendFloat(b, 339.7784, 'g', -1, 64) }
+func BenchmarkAppendFloatExp(b *testing.B)     { benchmarkAppendFloat(b, -5.09e75, 'g', -1, 64) }
+func BenchmarkAppendFloatNegExp(b *testing.B)  { benchmarkAppendFloat(b, -5.11e-95, 'g', -1, 64) }
+func BenchmarkAppendFloatBig(b *testing.B) {
+	benchmarkAppendFloat(b, 123456789123456789123456789, 'g', -1, 64)
+}
+
+func BenchmarkAppendFloat32Integer(b *testing.B)       { benchmarkAppendFloat(b, 33909, 'g', -1, 32) }
+func BenchmarkAppendFloat32ExactFraction(b *testing.B) { benchmarkAppendFloat(b, 3.375, 'g', -1, 32) }
+func BenchmarkAppendFloat32Point(b *testing.B)         { benchmarkAppendFloat(b, 339.7784, 'g', -1, 32) }
+func BenchmarkAppendFloat32Exp(b *testing.B)           { benchmarkAppendFloat(b, -5.09e25, 'g', -1, 32) }
+func BenchmarkAppendFloat32NegExp(b *testing.B)        { benchmarkAppendFloat(b, -5.11e-25, 'g', -1, 32) }
+
+func BenchmarkAppendFloat64Fixed1(b *testing.B) { benchmarkAppendFloat(b, 123456, 'e', 3, 64) }
+func BenchmarkAppendFloat64Fixed2(b *testing.B) { benchmarkAppendFloat(b, 123.456, 'e', 3, 64) }
+func BenchmarkAppendFloat64Fixed3(b *testing.B) { benchmarkAppendFloat(b, 1.23456e+78, 'e', 3, 64) }
+func BenchmarkAppendFloat64Fixed4(b *testing.B) { benchmarkAppendFloat(b, 1.23456e-78, 'e', 3, 64) }