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ensure.go
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/
ensure.go
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// Package ensure provides utilities for testing to ensure the
// given conditions are met and Fatal if they aren't satisified.
//
// The various functions here show a useful error message automatically
// including identifying source location. They additionally support arbitary
// arguments which will be printed using the spew library.
package ensure
import (
"bytes"
"fmt"
"path/filepath"
"reflect"
"regexp"
"strings"
"github.com/davecgh/go-spew/spew"
"github.com/facebookgo/stack"
subsetp "github.com/facebookgo/subset"
)
// Fataler defines the minimal interface necessary to trigger a Fatal when a
// condition is hit. testing.T & testing.B satisfy this for example.
type Fataler interface {
Fatal(a ...interface{})
}
// cond represents a condition that wasn't satisfied, and is useful to generate
// log messages.
type cond struct {
Fataler Fataler
Skip int
Format string
FormatArgs []interface{}
Extra []interface{}
DisableDeleteSelf bool
}
// This deletes "ensure.go:xx" removing a confusing piece of information since
// it will be an internal reference.
var deleteSelf = strings.Repeat("\b", 15)
func (c cond) String() string {
var b bytes.Buffer
if c.DisableDeleteSelf {
fmt.Fprint(&b, "\n")
} else {
fmt.Fprint(&b, deleteSelf)
}
fmt.Fprint(&b, pstack(stack.Callers(c.Skip+1), c.DisableDeleteSelf))
if c.Format != "" {
fmt.Fprintf(&b, c.Format, c.FormatArgs...)
}
if len(c.Extra) != 0 {
fmt.Fprint(&b, "\n")
fmt.Fprint(&b, tsdump(c.Extra...))
}
return b.String()
}
// fatal triggers the fatal and logs the cond's message. It adds 2 to Skip, to
// skip itself as well as the caller.
func fatal(c cond) {
c.Skip = c.Skip + 2
c.Fataler.Fatal(c.String())
}
// Err ensures the error satisfies the given regular expression.
func Err(t Fataler, err error, re *regexp.Regexp, a ...interface{}) {
if err == nil && re == nil {
return
}
if err == nil && re != nil {
fatal(cond{
Fataler: t,
Format: `expected error: "%s" but got a nil error`,
FormatArgs: []interface{}{re},
Extra: a,
})
return
}
if err != nil && re == nil {
fatal(cond{
Fataler: t,
Format: `unexpected error: %s`,
FormatArgs: []interface{}{err},
Extra: a,
})
return
}
if !re.MatchString(err.Error()) {
fatal(cond{
Fataler: t,
Format: `expected error: "%s" but got "%s"`,
FormatArgs: []interface{}{re, err},
Extra: a,
})
}
}
// DeepEqual ensures actual and expected are equal. It does so using
// reflect.DeepEqual.
func DeepEqual(t Fataler, actual, expected interface{}, a ...interface{}) {
if !reflect.DeepEqual(actual, expected) {
fatal(cond{
Fataler: t,
Format: "expected these to be equal:\nACTUAL:\n%s\nEXPECTED:\n%s",
FormatArgs: []interface{}{spew.Sdump(actual), tsdump(expected)},
Extra: a,
})
}
}
// NotDeepEqual ensures actual and expected are not equal. It does so using
// reflect.DeepEqual.
func NotDeepEqual(t Fataler, actual, expected interface{}, a ...interface{}) {
if reflect.DeepEqual(actual, expected) {
fatal(cond{
Fataler: t,
Format: "expected two different values, but got the same:\n%s",
FormatArgs: []interface{}{tsdump(actual)},
Extra: a,
})
}
}
// Subset ensures actual matches subset.
func Subset(t Fataler, actual, subset interface{}, a ...interface{}) {
if !subsetp.Check(subset, actual) {
fatal(cond{
Fataler: t,
Format: "expected subset not found:\nACTUAL:\n%s\nEXPECTED SUBSET\n%s",
FormatArgs: []interface{}{spew.Sdump(actual), tsdump(subset)},
Extra: a,
})
}
}
// DisorderedSubset attempts to find all the given subsets in the list of actuals.
// Does not allow one actual to match more than one subset, be warray of the
// possibility of insufficiently specific subsets.
func DisorderedSubset(t Fataler, a, s interface{}, extra ...interface{}) {
actuals := toInterfaceSlice(a)
subsets := toInterfaceSlice(s)
used := make([]bool, len(actuals))
matches := 0
for _, subset := range subsets {
for i, actual := range actuals {
if used[i] {
continue
}
if subsetp.Check(subset, actual) {
matches++
used[i] = true
break
}
}
}
if matches != len(subsets) {
fatal(cond{
Fataler: t,
Format: "expected subsets not found:\nACTUAL:\n%s\nEXPECTED SUBSET\n%s",
FormatArgs: []interface{}{spew.Sdump(actuals), tsdump(subsets)},
Extra: extra,
})
}
}
// Nil ensures v is nil.
func Nil(t Fataler, v interface{}, a ...interface{}) {
vs := tsdump(v)
sp := " "
if strings.Contains(vs[:len(vs)-1], "\n") {
sp = "\n"
}
if v != nil {
// Special case errors for prettier output.
if _, ok := v.(error); ok {
fatal(cond{
Fataler: t,
Format: `unexpected error: %s`,
FormatArgs: []interface{}{v},
Extra: a,
})
} else {
fatal(cond{
Fataler: t,
Format: "expected nil value but got:%s%s",
FormatArgs: []interface{}{sp, vs},
Extra: a,
})
}
}
}
// NotNil ensures v is not nil.
func NotNil(t Fataler, v interface{}, a ...interface{}) {
if v == nil {
fatal(cond{
Fataler: t,
Format: "expected a value but got nil",
Extra: a,
})
}
}
// True ensures v is true.
func True(t Fataler, v bool, a ...interface{}) {
if !v {
fatal(cond{
Fataler: t,
Format: "expected true but got false",
Extra: a,
})
}
}
// False ensures v is false.
func False(t Fataler, v bool, a ...interface{}) {
if v {
fatal(cond{
Fataler: t,
Format: "expected false but got true",
Extra: a,
})
}
}
// StringContains ensures string s contains the string substr.
func StringContains(t Fataler, s, substr string, a ...interface{}) {
if !strings.Contains(s, substr) {
format := `expected substring "%s" was not found in "%s"`
// use multi line output if either string contains newlines
if strings.Contains(s, "\n") || strings.Contains(substr, "\n") {
format = "expected substring was not found:\nEXPECTED SUBSTRING:\n%s\nACTUAL:\n%s"
}
fatal(cond{
Fataler: t,
Format: format,
FormatArgs: []interface{}{substr, s},
Extra: a,
})
}
}
// StringDoesNotContain ensures string s does not contain the string substr.
func StringDoesNotContain(t Fataler, s, substr string, a ...interface{}) {
if strings.Contains(s, substr) {
fatal(cond{
Fataler: t,
Format: `substring "%s" was not supposed to be found in "%s"`,
FormatArgs: []interface{}{substr, s},
Extra: a,
})
}
}
// SameElements ensures the two given slices contain the same elements,
// ignoring the order. It uses DeepEqual for element comparison.
func SameElements(t Fataler, actual, expected interface{}, extra ...interface{}) {
actualSlice := toInterfaceSlice(actual)
expectedSlice := toInterfaceSlice(expected)
if len(actualSlice) != len(expectedSlice) {
fatal(cond{
Fataler: t,
Format: "expected same elements but found slices of different lengths:\nACTUAL:\n%s\nEXPECTED\n%s",
FormatArgs: []interface{}{tsdump(actual), tsdump(expected)},
Extra: extra,
})
}
used := map[int]bool{}
outer:
for _, a := range expectedSlice {
for i, b := range actualSlice {
if !used[i] && reflect.DeepEqual(a, b) {
used[i] = true
continue outer
}
}
fatal(cond{
Fataler: t,
Format: "missing expected element:\nACTUAL:\n%s\nEXPECTED:\n%s\nMISSING ELEMENT\n%s",
FormatArgs: []interface{}{tsdump(actual), tsdump(expected), tsdump(a)},
Extra: extra,
})
}
}
// PanicDeepEqual ensures a panic occurs and the recovered value is DeepEqual
// to the expected value.
func PanicDeepEqual(t Fataler, expected interface{}, a ...interface{}) {
if expected == nil {
panic("can't pass nil to ensure.PanicDeepEqual")
}
actual := recover()
if !reflect.DeepEqual(actual, expected) {
fatal(cond{
Fataler: t,
Format: "expected these to be equal:\nACTUAL:\n%s\nEXPECTED:\n%s",
FormatArgs: []interface{}{spew.Sdump(actual), tsdump(expected)},
Extra: a,
DisableDeleteSelf: true,
})
}
}
// makes any slice into an []interface{}
func toInterfaceSlice(v interface{}) []interface{} {
rv := reflect.ValueOf(v)
l := rv.Len()
ret := make([]interface{}, l)
for i := 0; i < l; i++ {
ret[i] = rv.Index(i).Interface()
}
return ret
}
// tsdump is Sdump without the trailing newline.
func tsdump(a ...interface{}) string {
return strings.TrimSpace(spew.Sdump(a...))
}
// pstack is the stack upto the Test function frame.
func pstack(s stack.Stack, skipPrefix bool) string {
first := s[0]
if isTestFrame(first) {
return fmt.Sprintf("%s:%d: ", filepath.Base(first.File), first.Line)
}
prefix := " "
if skipPrefix {
prefix = ""
}
var snew stack.Stack
for _, f := range s {
snew = append(snew, f)
if isTestFrame(f) {
return prefix + snew.String() + "\n"
}
}
return prefix + s.String() + "\n"
}
func isTestFrame(f stack.Frame) bool {
return strings.HasPrefix(f.Name, "Test")
}