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Add a quickcheck package which is a little like the Haskell one of the same
name. R=rsc APPROVED=rsc DELTA=566 (566 added, 0 deleted, 0 changed) OCL=35974 CL=36111
This commit is contained in:
Adam Langley
parent
74aa9dd55a
commit
878d0e1efd
5 changed files with 571 additions and 7 deletions
367
src/pkg/testing/quick/quick.go
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367
src/pkg/testing/quick/quick.go
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// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// This package implements utility functions to help with black box testing.
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package quick
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import (
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"flag";
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"fmt";
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"math";
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"os";
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"rand";
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"reflect";
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"strings";
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)
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var defaultMaxCount *int = flag.Int("quickchecks", 100, "The default number of iterations for each check")
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// A Generator can generate random values of its own type.
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type Generator interface {
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// Generate returns a random instance of the type on which it is a
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// method using the size as a size hint.
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Generate(rand *rand.Rand, size int) reflect.Value;
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}
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// randFloat32 generates a random float taking the full range of a float32.
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func randFloat32(rand *rand.Rand) float32 {
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f := rand.Float64() * math.MaxFloat32;
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if rand.Int() & 1 == 1 {
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f = -f;
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}
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return float32(f);
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}
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// randFloat64 generates a random float taking the full range of a float64.
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func randFloat64(rand *rand.Rand) float64 {
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f := rand.Float64();
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if rand.Int() & 1 == 1 {
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f = -f;
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}
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return f;
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}
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// randInt64 returns a random integer taking half the range of an int64.
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func randInt64(rand *rand.Rand) int64 {
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return rand.Int63() - 1<<62;
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}
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// complexSize is the maximum length of arbitrary values that contain other
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// values.
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const complexSize = 50
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// Value returns an arbitrary value of the given type.
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// If the type implements the Generator interface, that will be used.
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// Note: in order to create arbitrary values for structs, all the members must be public.
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func Value(t reflect.Type, rand *rand.Rand) (value reflect.Value, ok bool) {
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if m, ok := reflect.MakeZero(t).Interface().(Generator); ok {
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return m.Generate(rand, complexSize), true;
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}
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switch concrete := t.(type) {
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case *reflect.BoolType:
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return reflect.NewValue(rand.Int() & 1 == 0), true;
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case *reflect.Float32Type:
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return reflect.NewValue(randFloat32(rand)), true;
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case *reflect.Float64Type:
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return reflect.NewValue(randFloat64(rand)), true;
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case *reflect.FloatType:
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if t.Size() == 4 {
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return reflect.NewValue(float(randFloat32(rand))), true;
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} else {
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return reflect.NewValue(float(randFloat64(rand))), true;
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}
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case *reflect.Int16Type:
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return reflect.NewValue(int16(randInt64(rand))), true;
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case *reflect.Int32Type:
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return reflect.NewValue(int32(randInt64(rand))), true;
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case *reflect.Int64Type:
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return reflect.NewValue(randInt64(rand)), true;
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case *reflect.Int8Type:
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return reflect.NewValue(int8(randInt64(rand))), true;
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case *reflect.IntType:
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return reflect.NewValue(int(randInt64(rand))), true;
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case *reflect.MapType:
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numElems := rand.Intn(complexSize);
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m := reflect.MakeMap(concrete);
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for i := 0; i < numElems; i++ {
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key, ok1 := Value(concrete.Key(), rand);
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value, ok2 := Value(concrete.Elem(), rand);
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if !ok1 || !ok2 {
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return nil, false;
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}
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m.SetElem(key, value);
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}
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return m, true;
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case *reflect.PtrType:
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v, ok := Value(concrete.Elem(), rand);
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if !ok {
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return nil, false;
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}
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p := reflect.MakeZero(concrete);
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p.(*reflect.PtrValue).PointTo(v);
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return p, true;
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case *reflect.SliceType:
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numElems := rand.Intn(complexSize);
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s := reflect.MakeSlice(concrete, numElems, numElems);
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for i := 0; i < numElems; i++ {
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v, ok := Value(concrete.Elem(), rand);
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if !ok {
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return nil, false;
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}
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s.Elem(i).SetValue(v);
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}
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return s, true;
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case *reflect.StringType:
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numChars := rand.Intn(complexSize);
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codePoints := make([]int, numChars);
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for i := 0; i < numChars; i++ {
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codePoints[i] = rand.Intn(0x10ffff);
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}
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return reflect.NewValue(string(codePoints)), true;
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case *reflect.StructType:
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s := reflect.MakeZero(t).(*reflect.StructValue);
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for i := 0; i < s.NumField(); i++ {
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v, ok := Value(concrete.Field(i).Type, rand);
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if !ok {
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return nil, false;
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}
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s.Field(i).SetValue(v);
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}
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return s, true;
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case *reflect.Uint16Type:
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return reflect.NewValue(uint16(randInt64(rand))), true;
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case *reflect.Uint32Type:
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return reflect.NewValue(uint32(randInt64(rand))), true;
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case *reflect.Uint64Type:
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return reflect.NewValue(uint64(randInt64(rand))), true;
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case *reflect.Uint8Type:
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return reflect.NewValue(uint8(randInt64(rand))), true;
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case *reflect.UintType:
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return reflect.NewValue(uint(randInt64(rand))), true;
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case *reflect.UintptrType:
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return reflect.NewValue(uintptr(randInt64(rand))), true;
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default:
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return nil, false;
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}
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return;
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}
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// A Config structure contains options for running a test.
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type Config struct {
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// MaxCount sets the maximum number of iterations. If zero,
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// MaxCountScale is used.
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MaxCount int;
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// MaxCountScale is a non-negative scale factor applied to the default
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// maximum. If zero, the default is unchanged.
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MaxCountScale float;
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// If non-nil, rand is a source of random numbers. Otherwise a default
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// pseudo-random source will be used.
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Rand *rand.Rand;
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// If non-nil, Values is a function which generates a slice of arbitrary
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// Values that are congruent with the arguments to the function being
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// tested. Otherwise, Values is used to generate the values.
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Values func([]reflect.Value, *rand.Rand);
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}
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var defaultConfig Config
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// getRand returns the *rand.Rand to use for a given Config.
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func (c *Config) getRand() *rand.Rand {
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if c.Rand == nil {
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return rand.New(rand.NewSource(0));
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}
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return c.Rand;
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}
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// getMaxCount returns the maximum number of iterations to run for a given
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// Config.
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func (c *Config) getMaxCount() (maxCount int) {
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maxCount = c.MaxCount;
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if maxCount == 0 {
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if c.MaxCountScale != 0 {
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maxCount = int(c.MaxCountScale * float(*defaultMaxCount));
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} else {
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maxCount = *defaultMaxCount;
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}
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}
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return;
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}
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// A SetupError is the result of an error in the way that check is being
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// used, independent of the functions being tested.
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type SetupError string
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func (s SetupError) String() string {
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return string(s);
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}
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// A CheckError is the result of Check finding an error.
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type CheckError struct {
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Count int;
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In []interface{};
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}
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func (s *CheckError) String() string {
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return fmt.Sprintf("#%d: failed on input %s", s.Count, toString(s.In));
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}
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// A CheckEqualError is the result CheckEqual finding an error.
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type CheckEqualError struct {
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CheckError;
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Out1 []interface{};
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Out2 []interface{};
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}
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func (s *CheckEqualError) String() string {
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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));
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}
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// Check looks for an input to f, any function that returns bool,
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// such that f returns false. It calls f repeatedly, with arbitrary
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// values for each argument. If f returns false on a given input,
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// Check returns that input as a *CheckError.
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// For example:
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//
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// func TestOddMultipleOfThree(t *testing.T) {
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// f := func(x int) bool {
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// y := OddMultipleOfThree(x);
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// return y%2 == 1 && y%3 == 0
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// }
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// if err := quick.Check(f, nil); err != nil {
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// t.Error(err);
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// }
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// }
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func Check(function interface{}, config *Config) (err os.Error) {
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if config == nil {
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config = &defaultConfig;
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}
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f, fType, ok := functionAndType(function);
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if !ok {
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err = SetupError("argument is not a function");
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return;
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}
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if fType.NumOut() != 1 {
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err = SetupError("function returns more than one value.");
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return;
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}
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if _, ok := fType.Out(0).(*reflect.BoolType); !ok {
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err = SetupError("function does not return a bool");
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return;
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}
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arguments := make([]reflect.Value, fType.NumIn());
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rand := config.getRand();
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maxCount := config.getMaxCount();
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for i := 0; i < maxCount; i++ {
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err = arbitraryValues(arguments, fType, config, rand);
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if err != nil {
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return;
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}
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if !f.Call(arguments)[0].(*reflect.BoolValue).Get() {
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err = &CheckError{i+1, toInterfaces(arguments)};
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return;
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}
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}
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return;
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}
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// CheckEqual looks for an input on which f and g return different results.
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// It calls f and g repeatedly with arbitrary values for each argument.
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// If f and g return different answers, CheckEqual returns a *CheckEqualError
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// describing the input and the outputs.
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func CheckEqual(f, g interface{}, config *Config) (err os.Error) {
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if config == nil {
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config = &defaultConfig;
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}
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x, xType, ok := functionAndType(f);
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if !ok {
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err = SetupError("f is not a function");
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return;
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}
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y, yType, ok := functionAndType(g);
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if !ok {
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err = SetupError("g is not a function");
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return;
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}
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if xType != yType {
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err = SetupError("functions have different types");
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return;
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}
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arguments := make([]reflect.Value, xType.NumIn());
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rand := config.getRand();
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maxCount := config.getMaxCount();
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for i := 0; i < maxCount; i++ {
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err = arbitraryValues(arguments, xType, config, rand);
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if err != nil {
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return;
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}
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xOut := toInterfaces(x.Call(arguments));
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yOut := toInterfaces(y.Call(arguments));
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if !reflect.DeepEqual(xOut, yOut) {
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err = &CheckEqualError{CheckError{i+1, toInterfaces(arguments)}, xOut, yOut};
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return;
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}
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}
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return;
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}
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// arbitraryValues writes Values to args such that args contains Values
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// suitable for calling f.
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func arbitraryValues(args []reflect.Value, f *reflect.FuncType, config *Config, rand *rand.Rand) (err os.Error) {
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if config.Values != nil {
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config.Values(args, rand);
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return;
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}
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for j := 0; j < len(args); j++ {
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var ok bool;
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args[j], ok = Value(f.In(j), rand);
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if !ok {
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err = SetupError(fmt.Sprintf("cannot create arbitrary value of type %s for argument %d", f.In(j), j));
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return;
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}
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}
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return;
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}
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func functionAndType(f interface{}) (v *reflect.FuncValue, t *reflect.FuncType, ok bool) {
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v, ok = reflect.NewValue(f).(*reflect.FuncValue);
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if !ok {
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return;
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}
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t = v.Type().(*reflect.FuncType);
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return;
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}
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func toInterfaces(values []reflect.Value) []interface{} {
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ret := make([]interface{}, len(values));
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for i, v := range values {
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ret[i] = v.Interface();
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}
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return ret;
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}
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func toString(interfaces []interface{}) string {
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s := make([]string, len(interfaces));
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for i, v := range interfaces {
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s[i] = fmt.Sprintf("%#v", v);
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}
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return strings.Join(s, ", ");
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}
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