| // 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. |
| |
| // This package implements utility functions to help with black box testing. |
| package quick |
| |
| import ( |
| "flag" |
| "fmt" |
| "math" |
| "os" |
| "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() |
| 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: in order to create arbitrary values for structs, all the members must be public. |
| func Value(t reflect.Type, rand *rand.Rand) (value reflect.Value, ok bool) { |
| if m, ok := reflect.MakeZero(t).Interface().(Generator); ok { |
| return m.Generate(rand, complexSize), true |
| } |
| |
| switch concrete := t.(type) { |
| case *reflect.BoolType: |
| return reflect.NewValue(rand.Int()&1 == 0), true |
| case *reflect.FloatType, *reflect.IntType, *reflect.UintType, *reflect.ComplexType: |
| switch t.Kind() { |
| case reflect.Float32: |
| return reflect.NewValue(randFloat32(rand)), true |
| case reflect.Float64: |
| return reflect.NewValue(randFloat64(rand)), true |
| case reflect.Complex64: |
| return reflect.NewValue(complex(randFloat32(rand), randFloat32(rand))), true |
| case reflect.Complex128: |
| return reflect.NewValue(complex(randFloat64(rand), randFloat64(rand))), true |
| case reflect.Int16: |
| return reflect.NewValue(int16(randInt64(rand))), true |
| case reflect.Int32: |
| return reflect.NewValue(int32(randInt64(rand))), true |
| case reflect.Int64: |
| return reflect.NewValue(randInt64(rand)), true |
| case reflect.Int8: |
| return reflect.NewValue(int8(randInt64(rand))), true |
| case reflect.Int: |
| return reflect.NewValue(int(randInt64(rand))), true |
| case reflect.Uint16: |
| return reflect.NewValue(uint16(randInt64(rand))), true |
| case reflect.Uint32: |
| return reflect.NewValue(uint32(randInt64(rand))), true |
| case reflect.Uint64: |
| return reflect.NewValue(uint64(randInt64(rand))), true |
| case reflect.Uint8: |
| return reflect.NewValue(uint8(randInt64(rand))), true |
| case reflect.Uint: |
| return reflect.NewValue(uint(randInt64(rand))), true |
| case reflect.Uintptr: |
| return reflect.NewValue(uintptr(randInt64(rand))), true |
| } |
| case *reflect.MapType: |
| numElems := rand.Intn(complexSize) |
| m := 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 nil, false |
| } |
| m.SetElem(key, value) |
| } |
| return m, true |
| case *reflect.PtrType: |
| v, ok := Value(concrete.Elem(), rand) |
| if !ok { |
| return nil, false |
| } |
| p := reflect.MakeZero(concrete) |
| p.(*reflect.PtrValue).PointTo(v) |
| return p, true |
| case *reflect.SliceType: |
| numElems := rand.Intn(complexSize) |
| s := reflect.MakeSlice(concrete, numElems, numElems) |
| for i := 0; i < numElems; i++ { |
| v, ok := Value(concrete.Elem(), rand) |
| if !ok { |
| return nil, false |
| } |
| s.Elem(i).SetValue(v) |
| } |
| return s, true |
| case *reflect.StringType: |
| numChars := rand.Intn(complexSize) |
| codePoints := make([]int, numChars) |
| for i := 0; i < numChars; i++ { |
| codePoints[i] = rand.Intn(0x10ffff) |
| } |
| return reflect.NewValue(string(codePoints)), true |
| case *reflect.StructType: |
| s := reflect.MakeZero(t).(*reflect.StructValue) |
| for i := 0; i < s.NumField(); i++ { |
| v, ok := Value(concrete.Field(i).Type, rand) |
| if !ok { |
| return nil, false |
| } |
| s.Field(i).SetValue(v) |
| } |
| return s, true |
| default: |
| return nil, false |
| } |
| |
| return |
| } |
| |
| // 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, Values is a function which generates a slice of arbitrary |
| // Values that are congruent with the arguments to the function being |
| // tested. Otherwise, Values is used to generate the values. |
| 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) String() string { return string(s) } |
| |
| // A CheckError is the result of Check finding an error. |
| type CheckError struct { |
| Count int |
| In []interface{} |
| } |
| |
| func (s *CheckError) String() 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) String() 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(function interface{}, config *Config) (err os.Error) { |
| if config == nil { |
| config = &defaultConfig |
| } |
| |
| f, fType, ok := functionAndType(function) |
| if !ok { |
| err = SetupError("argument is not a function") |
| return |
| } |
| |
| if fType.NumOut() != 1 { |
| err = SetupError("function returns more than one value.") |
| return |
| } |
| if _, ok := fType.Out(0).(*reflect.BoolType); !ok { |
| 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 !f.Call(arguments)[0].(*reflect.BoolValue).Get() { |
| 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 os.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.FuncType, config *Config, rand *rand.Rand) (err os.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.FuncValue, t *reflect.FuncType, ok bool) { |
| v, ok = reflect.NewValue(f).(*reflect.FuncValue) |
| if !ok { |
| return |
| } |
| t = v.Type().(*reflect.FuncType) |
| 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, ", ") |
| } |
