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Source file src/math/big/decimal_test.go

Documentation: math/big

  // 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()
  			}
  		})
  	}
  }
  

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