1 files changed, 134 insertions, 0 deletions
diff --git a/src/math/big/decimal_test.go b/src/math/big/decimal_test.go
new file mode 100644
index 0000000..424811e
--- /dev/null
+++ b/src/math/big/decimal_test.go
@@ -0,0 +1,134 @@
+// Copyright 2015 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 big
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestDecimalString(t *testing.T) {
+	for _, test := range []struct {
+		x    decimal
+		want string
+	}{
+		{want: "0"},
+		{decimal{nil, 1000}, "0"}, // exponent of 0 is ignored
+		{decimal{[]byte("12345"), 0}, "0.12345"},
+		{decimal{[]byte("12345"), -3}, "0.00012345"},
+		{decimal{[]byte("12345"), +3}, "123.45"},
+		{decimal{[]byte("12345"), +10}, "1234500000"},
+	} {
+		if got := test.x.String(); got != test.want {
+			t.Errorf("%v == %s; want %s", test.x, got, test.want)
+		}
+	}
+}
+
+func TestDecimalInit(t *testing.T) {
+	for _, test := range []struct {
+		x     Word
+		shift int
+		want  string
+	}{
+		{0, 0, "0"},
+		{0, -100, "0"},
+		{0, 100, "0"},
+		{1, 0, "1"},
+		{1, 10, "1024"},
+		{1, 100, "1267650600228229401496703205376"},
+		{1, -100, "0.0000000000000000000000000000007888609052210118054117285652827862296732064351090230047702789306640625"},
+		{12345678, 8, "3160493568"},
+		{12345678, -8, "48225.3046875"},
+		{195312, 9, "99999744"},
+		{1953125, 9, "1000000000"},
+	} {
+		var d decimal
+		d.init(nat{test.x}.norm(), test.shift)
+		if got := d.String(); got != test.want {
+			t.Errorf("%d << %d == %s; want %s", test.x, test.shift, got, test.want)
+		}
+	}
+}
+
+func TestDecimalRounding(t *testing.T) {
+	for _, test := range []struct {
+		x              uint64
+		n              int
+		down, even, up string
+	}{
+		{0, 0, "0", "0", "0"},
+		{0, 1, "0", "0", "0"},
+
+		{1, 0, "0", "0", "10"},
+		{5, 0, "0", "0", "10"},
+		{9, 0, "0", "10", "10"},
+
+		{15, 1, "10", "20", "20"},
+		{45, 1, "40", "40", "50"},
+		{95, 1, "90", "100", "100"},
+
+		{12344999, 4, "12340000", "12340000", "12350000"},
+		{12345000, 4, "12340000", "12340000", "12350000"},
+		{12345001, 4, "12340000", "12350000", "12350000"},
+		{23454999, 4, "23450000", "23450000", "23460000"},
+		{23455000, 4, "23450000", "23460000", "23460000"},
+		{23455001, 4, "23450000", "23460000", "23460000"},
+
+		{99994999, 4, "99990000", "99990000", "100000000"},
+		{99995000, 4, "99990000", "100000000", "100000000"},
+		{99999999, 4, "99990000", "100000000", "100000000"},
+
+		{12994999, 4, "12990000", "12990000", "13000000"},
+		{12995000, 4, "12990000", "13000000", "13000000"},
+		{12999999, 4, "12990000", "13000000", "13000000"},
+	} {
+		x := nat(nil).setUint64(test.x)
+
+		var d decimal
+		d.init(x, 0)
+		d.roundDown(test.n)
+		if got := d.String(); got != test.down {
+			t.Errorf("roundDown(%d, %d) = %s; want %s", test.x, test.n, got, test.down)
+		}
+
+		d.init(x, 0)
+		d.round(test.n)
+		if got := d.String(); got != test.even {
+			t.Errorf("round(%d, %d) = %s; want %s", test.x, test.n, got, test.even)
+		}
+
+		d.init(x, 0)
+		d.roundUp(test.n)
+		if got := d.String(); got != test.up {
+			t.Errorf("roundUp(%d, %d) = %s; want %s", test.x, test.n, got, test.up)
+		}
+	}
+}
+
+var sink string
+
+func BenchmarkDecimalConversion(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		for shift := -100; shift <= +100; shift++ {
+			var d decimal
+			d.init(natOne, shift)
+			sink = d.String()
+		}
+	}
+}
+
+func BenchmarkFloatString(b *testing.B) {
+	x := new(Float)
+	for _, prec := range []uint{1e2, 1e3, 1e4, 1e5} {
+		x.SetPrec(prec).SetRat(NewRat(1, 3))
+		b.Run(fmt.Sprintf("%v", prec), func(b *testing.B) {
+			b.ReportAllocs()
+			for i := 0; i < b.N; i++ {
+				sink = x.String()
+			}
+		})
+	}
+}