go/test/zerodivide.go

// $G $F.go && $L $F.$A && ./$A.out

// Copyright 2010 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 main

import (
	"fmt"
	"math"
	"strings"
	"syscall"
)

type Error interface {
	String() string
}

type ErrorTest struct {
	name	string
	fn	func()
	err	string
}

var (
	i, j, k int = 0, 0, 1
	i8, j8, k8 int8 = 0, 0, 1
	i16, j16, k16 int16 = 0, 0, 1
	i32, j32, k32 int32 = 0, 0, 1
	i64, j64, k64 int64 = 0, 0, 1

	u, v, w uint = 0, 0, 1
	u8, v8, w8 uint8 = 0, 0, 1
	u16, v16, w16 uint16 = 0, 0, 1
	u32, v32, w32 uint32 = 0, 0, 1
	u64, v64, w64 uint64 = 0, 0, 1
	up, vp, wp uintptr = 0, 0, 1

	f, g, h float = 0, 0, 1
	f32, g32, h32 float32 = 0, 0, 1
	f64, g64, h64, inf, negInf, nan float64 = 0, 0, 1, math.Inf(1), math.Inf(-1), math.NaN()

	c, d, e complex = 0+0i, 0+0i, 1+1i
	c64, d64, e64 complex64 = 0+0i, 0+0i, 1+1i
	c128, d128, e128 complex128 = 0+0i, 0+0i, 1+1i
)

var tmp interface{}

// We could assign to _ but the compiler optimizes it too easily.
func use(v interface{}) {
	tmp = v
}

// Verify error/no error for all types.
var errorTests = []ErrorTest{
	// All integer divide by zero should error.
	ErrorTest{ "int 0/0", func() { use(i/j) }, "divide", },
	ErrorTest{ "int8 0/0", func() { use(i8/j8) }, "divide", },
	ErrorTest{ "int16 0/0", func() { use(i16/j16) }, "divide", },
	ErrorTest{ "int32 0/0", func() { use(i32/j32) }, "divide", },
	ErrorTest{ "int64 0/0", func() { use(i64/j64) }, "divide", },

	ErrorTest{ "int 1/0", func() { use(k/j) }, "divide", },
	ErrorTest{ "int8 1/0", func() { use(k8/j8) }, "divide", },
	ErrorTest{ "int16 1/0", func() { use(k16/j16) }, "divide", },
	ErrorTest{ "int32 1/0", func() { use(k32/j32) }, "divide", },
	ErrorTest{ "int64 1/0", func() { use(k64/j64) }, "divide", },

	ErrorTest{ "uint 0/0", func() { use(u/v) }, "divide", },
	ErrorTest{ "uint8 0/0", func() { use(u8/v8) }, "divide", },
	ErrorTest{ "uint16 0/0", func() { use(u16/v16) }, "divide", },
	ErrorTest{ "uint32 0/0", func() { use(u32/v32) }, "divide", },
	ErrorTest{ "uint64 0/0", func() { use(u64/v64) }, "divide", },
	ErrorTest{ "uintptr 0/0", func() { use(up/vp) }, "divide", },

	ErrorTest{ "uint 1/0", func() { use(w/v) }, "divide", },
	ErrorTest{ "uint8 1/0", func() { use(w8/v8) }, "divide", },
	ErrorTest{ "uint16 1/0", func() { use(w16/v16) }, "divide", },
	ErrorTest{ "uint32 1/0", func() { use(w32/v32) }, "divide", },
	ErrorTest{ "uint64 1/0", func() { use(w64/v64) }, "divide", },
	ErrorTest{ "uintptr 1/0", func() { use(wp/vp) }, "divide", },

	// All floating divide by zero should not error.
	ErrorTest{ "float 0/0", func() { use(f/g) }, "", },
	ErrorTest{ "float32 0/0", func() { use(f32/g32) }, "", },
	ErrorTest{ "float64 0/0", func() { use(f64/g64) }, "", },

	ErrorTest{ "float 1/0", func() { use(h/g) }, "", },
	ErrorTest{ "float32 1/0", func() { use(h32/g32) }, "", },
	ErrorTest{ "float64 1/0", func() { use(h64/g64) }, "", },
	ErrorTest{ "float64 inf/0", func() { use(inf/g64) }, "", },
	ErrorTest{ "float64 -inf/0", func() { use(negInf/g64) }, "", },
	ErrorTest{ "float64 nan/0", func() { use(nan/g64) }, "", },

	// All complex divide by zero should not error.
	ErrorTest{ "complex 0/0", func() { use(c/d) }, "", },
	ErrorTest{ "complex64 0/0", func() { use(c64/d64) }, "", },
	ErrorTest{ "complex128 0/0", func() { use(c128/d128) }, "", },

	ErrorTest{ "complex 1/0", func() { use(e/d) }, "", },
	ErrorTest{ "complex64 1/0", func() { use(e64/d64) }, "", },
	ErrorTest{ "complex128 1/0", func() { use(e128/d128) }, "", },
}

func error(fn func()) (error string) {
	defer func() {
		if e := recover(); e != nil {
			error = e.(Error).String()
		}
	}()
	fn()
	return ""
}

type FloatTest struct{
	f, g	float64
	out	float64
}

var floatTests = []FloatTest{
	FloatTest{0, 0, nan},
	FloatTest{nan, 0, nan},
	FloatTest{inf, 0, inf},
	FloatTest{negInf, 0, negInf},
}

func alike(a, b float64) bool {
	switch {
	case math.IsNaN(a) && math.IsNaN(b):
		return true
	case a == b:
		return math.Signbit(a) == math.Signbit(b)
	}
	return false
}

func main() {
	for _, t := range errorTests {
		if t.err != "" && syscall.OS == "nacl" {
			continue
		}
		err := error(t.fn)
		switch {
		case t.err == "" && err == "":
			// fine
		case t.err != "" && err == "":
			fmt.Printf("%s: expected %q; got no error\n", t.name, t.err)
		case t.err == "" && err != "":
			fmt.Printf("%s: expected no error; got %q\n", t.name, err)
		case t.err != "" && err != "":
			if strings.Index(err, t.err) < 0 {
				fmt.Printf("%s: expected %q; got %q\n", t.name, t.err, err)
				continue
			}
		}
	}

	// At this point we know we don't error on the values we're testing
	for _, t := range floatTests {
		x := t.f/t.g
		if !alike(x, t.out) {
			fmt.Printf("%v/%v: expected %g error; got %g\n", t.f, t.g, t.out, x)
		}
	}
}