1 files changed, 358 insertions, 0 deletions
diff --git a/src/testing/quick/quick.go b/src/testing/quick/quick.go
new file mode 100644
index 000000000..909c65f78
--- /dev/null
+++ b/src/testing/quick/quick.go
@@ -0,0 +1,358 @@
+// 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.
+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) {
+	if m, ok := reflect.Zero(t).Interface().(Generator); ok {
+		return m.Generate(rand, complexSize), 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(complexSize)
+		v.Set(reflect.MakeMap(concrete))
+		for i := 0; i < numElems; i++ {
+			key, ok1 := Value(concrete.Key(), rand)
+			value, ok2 := Value(concrete.Elem(), rand)
+			if !ok1 || !ok2 {
+				return reflect.Value{}, false
+			}
+			v.SetMapIndex(key, value)
+		}
+	case reflect.Ptr:
+		elem, ok := Value(concrete.Elem(), rand)
+		if !ok {
+			return reflect.Value{}, false
+		}
+		v.Set(reflect.New(concrete.Elem()))
+		v.Elem().Set(elem)
+	case reflect.Slice:
+		numElems := rand.Intn(complexSize)
+		v.Set(reflect.MakeSlice(concrete, numElems, numElems))
+		for i := 0; i < numElems; i++ {
+			elem, ok := Value(concrete.Elem(), rand)
+			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:
+		for i := 0; i < v.NumField(); i++ {
+			elem, ok := Value(concrete.Field(i).Type, rand)
+			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 Values 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) (err error) {
+	if config == nil {
+		config = &defaultConfig
+	}
+
+	fVal, fType, ok := functionAndType(f)
+	if !ok {
+		err = SetupError("argument is not a function")
+		return
+	}
+
+	if fType.NumOut() != 1 {
+		err = SetupError("function returns more than one value.")
+		return
+	}
+	if fType.Out(0).Kind() != reflect.Bool {
+		err = SetupError("function does not return a bool")
+		return
+	}
+
+	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
+		}
+
+		if !fVal.Call(arguments)[0].Bool() {
+			err = &CheckError{i + 1, toInterfaces(arguments)}
+			return
+		}
+	}
+
+	return
+}
+
+// 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) (err error) {
+	if config == nil {
+		config = &defaultConfig
+	}
+
+	x, xType, ok := functionAndType(f)
+	if !ok {
+		err = SetupError("f is not a function")
+		return
+	}
+	y, yType, ok := functionAndType(g)
+	if !ok {
+		err = SetupError("g is not a function")
+		return
+	}
+
+	if xType != yType {
+		err = SetupError("functions have different types")
+		return
+	}
+
+	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
+		}
+
+		xOut := toInterfaces(x.Call(arguments))
+		yOut := toInterfaces(y.Call(arguments))
+
+		if !reflect.DeepEqual(xOut, yOut) {
+			err = &CheckEqualError{CheckError{i + 1, toInterfaces(arguments)}, xOut, yOut}
+			return
+		}
+	}
+
+	return
+}
+
+// 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, ", ")
+}