src/testing/quick/quick.go - go - Git at Google

 // 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 quick implements utility functions to help with black box testing.
 //
 // The testing/quick package is frozen and is not accepting new features.
 package quick

 import (
 	"flag"
 	"fmt"
 	"math"
 	"math/rand"
 	"reflect"
 	"strings"
 )

 var defaultMaxCount *int = flag.Int("quickchecks", 100, "The default number of iterations for each check")

 // A Generator can generate random values of its own type.
 type Generator interface {
 	// Generate returns a random instance of the type on which it is a
 	// method using the size as a size hint.
 	Generate(rand *rand.Rand, size int) reflect.Value
 }

 // randFloat32 generates a random float taking the full range of a float32.
 func randFloat32(rand *rand.Rand) float32 {
 	f := rand.Float64() * math.MaxFloat32
 	if rand.Int()&1 == 1 {
 		f = -f
 	}
 	return float32(f)
 }

 // randFloat64 generates a random float taking the full range of a float64.
 func randFloat64(rand *rand.Rand) float64 {
 	f := rand.Float64() * math.MaxFloat64
 	if rand.Int()&1 == 1 {
 		f = -f
 	}
 	return f
 }

 // randInt64 returns a random integer taking half the range of an int64.
 func randInt64(rand *rand.Rand) int64 { return rand.Int63() - 1<<62 }

 // complexSize is the maximum length of arbitrary values that contain other
 // values.
 const complexSize = 50

 // Value returns an arbitrary value of the given type.
 // If the type implements the Generator interface, that will be used.
 // Note: To create arbitrary values for structs, all the fields must be exported.
 func Value(t reflect.Type, rand *rand.Rand) (value reflect.Value, ok bool) {
 	return sizedValue(t, rand, complexSize)
 }

 // sizedValue returns an arbitrary value of the given type. The size
 // hint is used for shrinking as a function of indirection level so
 // that recursive data structures will terminate.
 func sizedValue(t reflect.Type, rand *rand.Rand, size int) (value reflect.Value, ok bool) {
 	if m, ok := reflect.Zero(t).Interface().(Generator); ok {
 		return m.Generate(rand, size), true
 	}

 	v := reflect.New(t).Elem()
 	switch concrete := t; concrete.Kind() {
 	case reflect.Bool:
 		v.SetBool(rand.Int()&1 == 0)
 	case reflect.Float32:
 		v.SetFloat(float64(randFloat32(rand)))
 	case reflect.Float64:
 		v.SetFloat(randFloat64(rand))
 	case reflect.Complex64:
 		v.SetComplex(complex(float64(randFloat32(rand)), float64(randFloat32(rand))))
 	case reflect.Complex128:
 		v.SetComplex(complex(randFloat64(rand), randFloat64(rand)))
 	case reflect.Int16:
 		v.SetInt(randInt64(rand))
 	case reflect.Int32:
 		v.SetInt(randInt64(rand))
 	case reflect.Int64:
 		v.SetInt(randInt64(rand))
 	case reflect.Int8:
 		v.SetInt(randInt64(rand))
 	case reflect.Int:
 		v.SetInt(randInt64(rand))
 	case reflect.Uint16:
 		v.SetUint(uint64(randInt64(rand)))
 	case reflect.Uint32:
 		v.SetUint(uint64(randInt64(rand)))
 	case reflect.Uint64:
 		v.SetUint(uint64(randInt64(rand)))
 	case reflect.Uint8:
 		v.SetUint(uint64(randInt64(rand)))
 	case reflect.Uint:
 		v.SetUint(uint64(randInt64(rand)))
 	case reflect.Uintptr:
 		v.SetUint(uint64(randInt64(rand)))
 	case reflect.Map:
 		numElems := rand.Intn(size)
 		v.Set(reflect.MakeMap(concrete))
 		for i := 0; i < numElems; i++ {
 			key, ok1 := sizedValue(concrete.Key(), rand, size)
 			value, ok2 := sizedValue(concrete.Elem(), rand, size)
 			if !ok1 || !ok2 {
 				return reflect.Value{}, false
 			}
 			v.SetMapIndex(key, value)
 		}
 	case reflect.Ptr:
 		if rand.Intn(size) == 0 {
 			v.Set(reflect.Zero(concrete)) // Generate nil pointer.
 		} else {
 			elem, ok := sizedValue(concrete.Elem(), rand, size)
 			if !ok {
 				return reflect.Value{}, false
 			}
 			v.Set(reflect.New(concrete.Elem()))
 			v.Elem().Set(elem)
 		}
 	case reflect.Slice:
 		numElems := rand.Intn(size)
 		sizeLeft := size - numElems
 		v.Set(reflect.MakeSlice(concrete, numElems, numElems))
 		for i := 0; i < numElems; i++ {
 			elem, ok := sizedValue(concrete.Elem(), rand, sizeLeft)
 			if !ok {
 				return reflect.Value{}, false
 			}
 			v.Index(i).Set(elem)
 		}
 	case reflect.Array:
 		for i := 0; i < v.Len(); i++ {
 			elem, ok := sizedValue(concrete.Elem(), rand, size)
 			if !ok {
 				return reflect.Value{}, false
 			}
 			v.Index(i).Set(elem)
 		}
 	case reflect.String:
 		numChars := rand.Intn(complexSize)
 		codePoints := make([]rune, numChars)
 		for i := 0; i < numChars; i++ {
 			codePoints[i] = rune(rand.Intn(0x10ffff))
 		}
 		v.SetString(string(codePoints))
 	case reflect.Struct:
 		n := v.NumField()
 		// Divide sizeLeft evenly among the struct fields.
 		sizeLeft := size
 		if n > sizeLeft {
 			sizeLeft = 1
 		} else if n > 0 {
 			sizeLeft /= n
 		}
 		for i := 0; i < n; i++ {
 			elem, ok := sizedValue(concrete.Field(i).Type, rand, sizeLeft)
 			if !ok {
 				return reflect.Value{}, false
 			}
 			v.Field(i).Set(elem)
 		}
 	default:
 		return reflect.Value{}, false
 	}

 	return v, true
 }

 // A Config structure contains options for running a test.
 type Config struct {
 	// MaxCount sets the maximum number of iterations. If zero,
 	// MaxCountScale is used.
 	MaxCount int
 	// MaxCountScale is a non-negative scale factor applied to the default
 	// maximum. If zero, the default is unchanged.
 	MaxCountScale float64
 	// If non-nil, rand is a source of random numbers. Otherwise a default
 	// pseudo-random source will be used.
 	Rand *rand.Rand
 	// If non-nil, the Values function generates a slice of arbitrary
 	// reflect.Values that are congruent with the arguments to the function
 	// being tested. Otherwise, the top-level Value function is used
 	// to generate them.
 	Values func([]reflect.Value, *rand.Rand)
 }

 var defaultConfig Config

 // getRand returns the *rand.Rand to use for a given Config.
 func (c *Config) getRand() *rand.Rand {
 	if c.Rand == nil {
 		return rand.New(rand.NewSource(0))
 	}
 	return c.Rand
 }

 // getMaxCount returns the maximum number of iterations to run for a given
 // Config.
 func (c *Config) getMaxCount() (maxCount int) {
 	maxCount = c.MaxCount
 	if maxCount == 0 {
 		if c.MaxCountScale != 0 {
 			maxCount = int(c.MaxCountScale * float64(*defaultMaxCount))
 		} else {
 			maxCount = *defaultMaxCount
 		}
 	}

 	return
 }

 // A SetupError is the result of an error in the way that check is being
 // used, independent of the functions being tested.
 type SetupError string

 func (s SetupError) Error() string { return string(s) }

 // A CheckError is the result of Check finding an error.
 type CheckError struct {
 	Count int
 	In    []interface{}
 }

 func (s *CheckError) Error() string {
 	return fmt.Sprintf("#%d: failed on input %s", s.Count, toString(s.In))
 }

 // A CheckEqualError is the result CheckEqual finding an error.
 type CheckEqualError struct {
 	CheckError
 	Out1 []interface{}
 	Out2 []interface{}
 }

 func (s *CheckEqualError) Error() string {
 	return fmt.Sprintf("#%d: failed on input %s. Output 1: %s. Output 2: %s", s.Count, toString(s.In), toString(s.Out1), toString(s.Out2))
 }

 // Check looks for an input to f, any function that returns bool,
 // such that f returns false. It calls f repeatedly, with arbitrary
 // values for each argument. If f returns false on a given input,
 // Check returns that input as a *CheckError.
 // For example:
 //
 // 	func TestOddMultipleOfThree(t *testing.T) {
 // 		f := func(x int) bool {
 // 			y := OddMultipleOfThree(x)
 // 			return y%2 == 1 && y%3 == 0
 // 		}
 // 		if err := quick.Check(f, nil); err != nil {
 // 			t.Error(err)
 // 		}
 // 	}
 func Check(f interface{}, config *Config) error {
 	if config == nil {
 		config = &defaultConfig
 	}

 	fVal, fType, ok := functionAndType(f)
 	if !ok {
 		return SetupError("argument is not a function")
 	}

 	if fType.NumOut() != 1 {
 		return SetupError("function does not return one value")
 	}
 	if fType.Out(0).Kind() != reflect.Bool {
 		return SetupError("function does not return a bool")
 	}

 	arguments := make([]reflect.Value, fType.NumIn())
 	rand := config.getRand()
 	maxCount := config.getMaxCount()

 	for i := 0; i < maxCount; i++ {
 		err := arbitraryValues(arguments, fType, config, rand)
 		if err != nil {
 			return err
 		}

 		if !fVal.Call(arguments)[0].Bool() {
 			return &CheckError{i + 1, toInterfaces(arguments)}
 		}
 	}

 	return nil
 }

 // CheckEqual looks for an input on which f and g return different results.
 // It calls f and g repeatedly with arbitrary values for each argument.
 // If f and g return different answers, CheckEqual returns a *CheckEqualError
 // describing the input and the outputs.
 func CheckEqual(f, g interface{}, config *Config) error {
 	if config == nil {
 		config = &defaultConfig
 	}

 	x, xType, ok := functionAndType(f)
 	if !ok {
 		return SetupError("f is not a function")
 	}
 	y, yType, ok := functionAndType(g)
 	if !ok {
 		return SetupError("g is not a function")
 	}

 	if xType != yType {
 		return SetupError("functions have different types")
 	}

 	arguments := make([]reflect.Value, xType.NumIn())
 	rand := config.getRand()
 	maxCount := config.getMaxCount()

 	for i := 0; i < maxCount; i++ {
 		err := arbitraryValues(arguments, xType, config, rand)
 		if err != nil {
 			return err
 		}

 		xOut := toInterfaces(x.Call(arguments))
 		yOut := toInterfaces(y.Call(arguments))

 		if !reflect.DeepEqual(xOut, yOut) {
 			return &CheckEqualError{CheckError{i + 1, toInterfaces(arguments)}, xOut, yOut}
 		}
 	}

 	return nil
 }

 // arbitraryValues writes Values to args such that args contains Values
 // suitable for calling f.
 func arbitraryValues(args []reflect.Value, f reflect.Type, config *Config, rand *rand.Rand) (err error) {
 	if config.Values != nil {
 		config.Values(args, rand)
 		return
 	}

 	for j := 0; j < len(args); j++ {
 		var ok bool
 		args[j], ok = Value(f.In(j), rand)
 		if !ok {
 			err = SetupError(fmt.Sprintf("cannot create arbitrary value of type %s for argument %d", f.In(j), j))
 			return
 		}
 	}

 	return
 }

 func functionAndType(f interface{}) (v reflect.Value, t reflect.Type, ok bool) {
 	v = reflect.ValueOf(f)
 	ok = v.Kind() == reflect.Func
 	if !ok {
 		return
 	}
 	t = v.Type()
 	return
 }

 func toInterfaces(values []reflect.Value) []interface{} {
 	ret := make([]interface{}, len(values))
 	for i, v := range values {
 		ret[i] = v.Interface()
 	}
 	return ret
 }

 func toString(interfaces []interface{}) string {
 	s := make([]string, len(interfaces))
 	for i, v := range interfaces {
 		s[i] = fmt.Sprintf("%#v", v)
 	}
 	return strings.Join(s, ", ")
 }
	// 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 quick implements utility functions to help with black box testing.
	//
	// The testing/quick package is frozen and is not accepting new features.
	package quick

	import (
	"flag"
	"fmt"
	"math"
	"math/rand"
	"reflect"
	"strings"
	)

	var defaultMaxCount *int = flag.Int("quickchecks", 100, "The default number of iterations for each check")

	// A Generator can generate random values of its own type.
	type Generator interface {
	// Generate returns a random instance of the type on which it is a
	// method using the size as a size hint.
	Generate(rand *rand.Rand, size int) reflect.Value
	}

	// randFloat32 generates a random float taking the full range of a float32.
	func randFloat32(rand *rand.Rand) float32 {
	f := rand.Float64() * math.MaxFloat32
	if rand.Int()&1 == 1 {
	f = -f
	}
	return float32(f)
	}

	// randFloat64 generates a random float taking the full range of a float64.
	func randFloat64(rand *rand.Rand) float64 {
	f := rand.Float64() * math.MaxFloat64
	if rand.Int()&1 == 1 {
	f = -f
	}
	return f
	}

	// randInt64 returns a random integer taking half the range of an int64.
	func randInt64(rand *rand.Rand) int64 { return rand.Int63() - 1<<62 }

	// complexSize is the maximum length of arbitrary values that contain other
	// values.
	const complexSize = 50

	// Value returns an arbitrary value of the given type.
	// If the type implements the Generator interface, that will be used.
	// Note: To create arbitrary values for structs, all the fields must be exported.
	func Value(t reflect.Type, rand *rand.Rand) (value reflect.Value, ok bool) {
	return sizedValue(t, rand, complexSize)
	}

	// sizedValue returns an arbitrary value of the given type. The size
	// hint is used for shrinking as a function of indirection level so
	// that recursive data structures will terminate.
	func sizedValue(t reflect.Type, rand *rand.Rand, size int) (value reflect.Value, ok bool) {
	if m, ok := reflect.Zero(t).Interface().(Generator); ok {
	return m.Generate(rand, size), true
	}

	v := reflect.New(t).Elem()
	switch concrete := t; concrete.Kind() {
	case reflect.Bool:
	v.SetBool(rand.Int()&1 == 0)
	case reflect.Float32:
	v.SetFloat(float64(randFloat32(rand)))
	case reflect.Float64:
	v.SetFloat(randFloat64(rand))
	case reflect.Complex64:
	v.SetComplex(complex(float64(randFloat32(rand)), float64(randFloat32(rand))))
	case reflect.Complex128:
	v.SetComplex(complex(randFloat64(rand), randFloat64(rand)))
	case reflect.Int16:
	v.SetInt(randInt64(rand))
	case reflect.Int32:
	v.SetInt(randInt64(rand))
	case reflect.Int64:
	v.SetInt(randInt64(rand))
	case reflect.Int8:
	v.SetInt(randInt64(rand))
	case reflect.Int:
	v.SetInt(randInt64(rand))
	case reflect.Uint16:
	v.SetUint(uint64(randInt64(rand)))
	case reflect.Uint32:
	v.SetUint(uint64(randInt64(rand)))
	case reflect.Uint64:
	v.SetUint(uint64(randInt64(rand)))
	case reflect.Uint8:
	v.SetUint(uint64(randInt64(rand)))
	case reflect.Uint:
	v.SetUint(uint64(randInt64(rand)))
	case reflect.Uintptr:
	v.SetUint(uint64(randInt64(rand)))
	case reflect.Map:
	numElems := rand.Intn(size)
	v.Set(reflect.MakeMap(concrete))
	for i := 0; i < numElems; i++ {
	key, ok1 := sizedValue(concrete.Key(), rand, size)
	value, ok2 := sizedValue(concrete.Elem(), rand, size)
	if !ok1 \|\| !ok2 {
	return reflect.Value{}, false
	}
	v.SetMapIndex(key, value)
	}
	case reflect.Ptr:
	if rand.Intn(size) == 0 {
	v.Set(reflect.Zero(concrete)) // Generate nil pointer.
	} else {
	elem, ok := sizedValue(concrete.Elem(), rand, size)
	if !ok {
	return reflect.Value{}, false
	}
	v.Set(reflect.New(concrete.Elem()))
	v.Elem().Set(elem)
	}
	case reflect.Slice:
	numElems := rand.Intn(size)
	sizeLeft := size - numElems
	v.Set(reflect.MakeSlice(concrete, numElems, numElems))
	for i := 0; i < numElems; i++ {
	elem, ok := sizedValue(concrete.Elem(), rand, sizeLeft)
	if !ok {
	return reflect.Value{}, false
	}
	v.Index(i).Set(elem)
	}
	case reflect.Array:
	for i := 0; i < v.Len(); i++ {
	elem, ok := sizedValue(concrete.Elem(), rand, size)
	if !ok {
	return reflect.Value{}, false
	}
	v.Index(i).Set(elem)
	}
	case reflect.String:
	numChars := rand.Intn(complexSize)
	codePoints := make([]rune, numChars)
	for i := 0; i < numChars; i++ {
	codePoints[i] = rune(rand.Intn(0x10ffff))
	}
	v.SetString(string(codePoints))
	case reflect.Struct:
	n := v.NumField()
	// Divide sizeLeft evenly among the struct fields.
	sizeLeft := size
	if n > sizeLeft {
	sizeLeft = 1
	} else if n > 0 {
	sizeLeft /= n
	}
	for i := 0; i < n; i++ {
	elem, ok := sizedValue(concrete.Field(i).Type, rand, sizeLeft)
	if !ok {
	return reflect.Value{}, false
	}
	v.Field(i).Set(elem)
	}
	default:
	return reflect.Value{}, false
	}

	return v, true
	}

	// A Config structure contains options for running a test.
	type Config struct {
	// MaxCount sets the maximum number of iterations. If zero,
	// MaxCountScale is used.
	MaxCount int
	// MaxCountScale is a non-negative scale factor applied to the default
	// maximum. If zero, the default is unchanged.
	MaxCountScale float64
	// If non-nil, rand is a source of random numbers. Otherwise a default
	// pseudo-random source will be used.
	Rand *rand.Rand
	// If non-nil, the Values function generates a slice of arbitrary
	// reflect.Values that are congruent with the arguments to the function
	// being tested. Otherwise, the top-level Value function is used
	// to generate them.
	Values func([]reflect.Value, *rand.Rand)
	}

	var defaultConfig Config

	// getRand returns the *rand.Rand to use for a given Config.
	func (c Config) getRand() rand.Rand {
	if c.Rand == nil {
	return rand.New(rand.NewSource(0))
	}
	return c.Rand
	}

	// getMaxCount returns the maximum number of iterations to run for a given
	// Config.
	func (c *Config) getMaxCount() (maxCount int) {
	maxCount = c.MaxCount
	if maxCount == 0 {
	if c.MaxCountScale != 0 {
	maxCount = int(c.MaxCountScale * float64(*defaultMaxCount))
	} else {
	maxCount = *defaultMaxCount
	}
	}

	return
	}

	// A SetupError is the result of an error in the way that check is being
	// used, independent of the functions being tested.
	type SetupError string

	func (s SetupError) Error() string { return string(s) }

	// A CheckError is the result of Check finding an error.
	type CheckError struct {
	Count int
	In []interface{}
	}

	func (s *CheckError) Error() string {
	return fmt.Sprintf("#%d: failed on input %s", s.Count, toString(s.In))
	}

	// A CheckEqualError is the result CheckEqual finding an error.
	type CheckEqualError struct {
	CheckError
	Out1 []interface{}
	Out2 []interface{}
	}

	func (s *CheckEqualError) Error() string {
	return fmt.Sprintf("#%d: failed on input %s. Output 1: %s. Output 2: %s", s.Count, toString(s.In), toString(s.Out1), toString(s.Out2))
	}

	// Check looks for an input to f, any function that returns bool,
	// such that f returns false. It calls f repeatedly, with arbitrary
	// values for each argument. If f returns false on a given input,
	// Check returns that input as a *CheckError.
	// For example:
	//
	// func TestOddMultipleOfThree(t *testing.T) {
	// f := func(x int) bool {
	// y := OddMultipleOfThree(x)
	// return y%2 == 1 && y%3 == 0
	// }
	// if err := quick.Check(f, nil); err != nil {
	// t.Error(err)
	// }
	// }
	func Check(f interface{}, config *Config) error {
	if config == nil {
	config = &defaultConfig
	}

	fVal, fType, ok := functionAndType(f)
	if !ok {
	return SetupError("argument is not a function")
	}

	if fType.NumOut() != 1 {
	return SetupError("function does not return one value")
	}
	if fType.Out(0).Kind() != reflect.Bool {
	return SetupError("function does not return a bool")
	}

	arguments := make([]reflect.Value, fType.NumIn())
	rand := config.getRand()
	maxCount := config.getMaxCount()

	for i := 0; i < maxCount; i++ {
	err := arbitraryValues(arguments, fType, config, rand)
	if err != nil {
	return err
	}

	if !fVal.Call(arguments)[0].Bool() {
	return &CheckError{i + 1, toInterfaces(arguments)}
	}
	}

	return nil
	}

	// CheckEqual looks for an input on which f and g return different results.
	// It calls f and g repeatedly with arbitrary values for each argument.
	// If f and g return different answers, CheckEqual returns a *CheckEqualError
	// describing the input and the outputs.
	func CheckEqual(f, g interface{}, config *Config) error {
	if config == nil {
	config = &defaultConfig
	}

	x, xType, ok := functionAndType(f)
	if !ok {
	return SetupError("f is not a function")
	}
	y, yType, ok := functionAndType(g)
	if !ok {
	return SetupError("g is not a function")
	}

	if xType != yType {
	return SetupError("functions have different types")
	}

	arguments := make([]reflect.Value, xType.NumIn())
	rand := config.getRand()
	maxCount := config.getMaxCount()

	for i := 0; i < maxCount; i++ {
	err := arbitraryValues(arguments, xType, config, rand)
	if err != nil {
	return err
	}

	xOut := toInterfaces(x.Call(arguments))
	yOut := toInterfaces(y.Call(arguments))

	if !reflect.DeepEqual(xOut, yOut) {
	return &CheckEqualError{CheckError{i + 1, toInterfaces(arguments)}, xOut, yOut}
	}
	}

	return nil
	}

	// arbitraryValues writes Values to args such that args contains Values
	// suitable for calling f.
	func arbitraryValues(args []reflect.Value, f reflect.Type, config Config, rand rand.Rand) (err error) {
	if config.Values != nil {
	config.Values(args, rand)
	return
	}

	for j := 0; j < len(args); j++ {
	var ok bool
	args[j], ok = Value(f.In(j), rand)
	if !ok {
	err = SetupError(fmt.Sprintf("cannot create arbitrary value of type %s for argument %d", f.In(j), j))
	return
	}
	}

	return
	}

	func functionAndType(f interface{}) (v reflect.Value, t reflect.Type, ok bool) {
	v = reflect.ValueOf(f)
	ok = v.Kind() == reflect.Func
	if !ok {
	return
	}
	t = v.Type()
	return
	}

	func toInterfaces(values []reflect.Value) []interface{} {
	ret := make([]interface{}, len(values))
	for i, v := range values {
	ret[i] = v.Interface()
	}
	return ret
	}

	func toString(interfaces []interface{}) string {
	s := make([]string, len(interfaces))
	for i, v := range interfaces {
	s[i] = fmt.Sprintf("%#v", v)
	}
	return strings.Join(s, ", ")
	}