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golden.go
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golden.go
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// Package golden is yet another package for working with *.golden test files,
// with a focus on simplicity through it's default behavior.
//
// Golden file names are based on the name of the test function and any subtest
// names by calling t.Name(). File names are sanitized to ensure they're
// compatible with Linux, macOS and Windows systems regardless of what crazy
// characters might be in a subtest's name.
//
// Usage
//
// Typical usage should look something like this:
//
// func TestExampleMyStruct(t *testing.T) {
// got, err := json.Marshal(&MyStruct{Foo: "Bar"})
// require.NoError(t, err)
//
// if golden.Update() {
// golden.Set(t, got)
// }
// want := golden.Get(t)
//
// assert.Equal(t, want, got)
// }
//
// The above example will read/write to:
//
// testdata/TestExampleMyStruct.golden
//
// To update the golden file (have golden.Update() return true), simply set the
// GOLDEN_UPDATE environment variable to one of "1", "y", "t", "yes", "on", or
// "true" when running tests.
//
// Sub-Tests
//
// As the golden filename is based on t.Name(), it works with sub-tests too,
// ensuring each sub-test gets it's own golden file. For example:
//
// func TestExampleMyStructTabular(t *testing.T) {
// tests := []struct {
// name string
// obj *MyStruct
// }{
// {name: "empty struct", obj: &MyStruct{}},
// {name: "full struct", obj: &MyStruct{Foo: "Bar"}},
// }
// for _, tt := range tests {
// t.Run(tt.name, func(t *testing.T) {
// got, err := json.Marshal(tt.obj)
// require.NoError(t, err)
//
// if golden.Update() {
// golden.Set(t, got)
// }
// want := golden.Get(t)
//
// assert.Equal(t, want, got)
// })
// }
// }
//
// The above example will read/write to:
//
// testdata/TestExampleMyStructTabular/empty_struct.golden
// testdata/TestExampleMyStructTabular/full_struct.golden
//
// Multiple Golden Files in a Single Test
//
// The "P" suffixed methods, GetP(), SetP(), and FileP(), all take a name
// argument which allows using specific golden files within a given *testing.T
// instance.
//
// func TestExampleMyStructP(t *testing.T) {
// gotJSON, _ := json.Marshal(&MyStruct{Foo: "Bar"})
// gotXML, _ := xml.Marshal(&MyStruct{Foo: "Bar"})
//
// if golden.Update() {
// golden.SetP(t, "json", gotJSON)
// golden.SetP(t, "xml", gotXML)
// }
//
// assert.Equal(t, golden.GetP(t, "json"), gotJSON)
// assert.Equal(t, golden.GetP(t, "xml"), gotXML)
// }
//
// The above example will read/write to:
//
// testdata/TestExampleMyStructP/json.golden
// testdata/TestExampleMyStructP/xml.golden
//
// This works with tabular tests too of course:
//
// func TestExampleMyStructTabularP(t *testing.T) {
// tests := []struct {
// name string
// obj *MyStruct
// }{
// {name: "empty struct", obj: &MyStruct{}},
// {name: "full struct", obj: &MyStruct{Foo: "Bar"}},
// }
// for _, tt := range tests {
// t.Run(tt.name, func(t *testing.T) {
// gotJSON, _ := json.Marshal(tt.obj)
// gotXML, _ := xml.Marshal(tt.obj)
//
// if golden.Update() {
// golden.SetP(t, "json", gotJSON)
// golden.SetP(t, "xml", gotXML)
// }
//
// assert.Equal(t, golden.GetP(t, "json"), gotJSON)
// assert.Equal(t, golden.GetP(t, "xml"), gotXML)
// })
// }
// }
//
// The above example will read/write to:
//
// testdata/TestExampleMyStructTabularP/empty_struct/json.golden
// testdata/TestExampleMyStructTabularP/empty_struct/xml.golden
// testdata/TestExampleMyStructTabularP/full_struct/json.golden
// testdata/TestExampleMyStructTabularP/full_struct/xml.golden
//
package golden
import (
"io/ioutil"
"os"
"path/filepath"
"strings"
"testing"
)
const (
DefaultDirMode = 0o755
DefaultFileMode = 0o644
DefaultSuffix = ".golden"
DefaultDirname = "testdata"
)
var DefaultUpdateFunc = EnvUpdateFunc
var global = New()
// File returns the filename of the golden file for the given *testing.T
// instance as determined by t.Name().
func File(t *testing.T) string {
t.Helper()
return global.File(t)
}
// Get returns the content of the golden file for the given *testing.T instance
// as determined by t.Name(). If no golden file can be found/read, it will fail
// the test by calling t.Fatal().
func Get(t *testing.T) []byte {
t.Helper()
return global.Get(t)
}
// Set writes given data to the golden file for the given *testing.T instance as
// determined by t.Name(). If writing fails it will fail the test by calling
// t.Fatal() with error details.
func Set(t *testing.T, data []byte) {
t.Helper()
global.Set(t, data)
}
// FileP returns the filename of the specifically named golden file for the
// given *testing.T instance as determined by t.Name().
func FileP(t *testing.T, name string) string {
t.Helper()
return global.FileP(t, name)
}
// GetP returns the content of the specifically named golden file belonging
// to the given *testing.T instance as determined by t.Name(). If no golden file
// can be found/read, it will fail the test with t.Fatal().
//
// This is very similar to Get(), but it allows multiple different golden files
// to be used within the same one *testing.T instance.
func GetP(t *testing.T, name string) []byte {
t.Helper()
return global.GetP(t, name)
}
// SetP writes given data of the specifically named golden file belonging to
// the given *testing.T instance as determined by t.Name(). If writing fails it
// will fail the test with t.Fatal() detailing the error.
//
// This is very similar to Set(), but it allows multiple different golden files
// to be used within the same one *testing.T instance.
func SetP(t *testing.T, name string, data []byte) {
t.Helper()
global.SetP(t, name, data)
}
// Update returns true when golden is set to update golden files. Should be used
// to determine if golden.Set() or golden.SetP() should be called or not.
//
// Default behavior uses EnvUpdateFunc() to check if the "GOLDEN_UPDATE"
// environment variable is set to a truthy value. To customize create a custom
// *Golden instance with New() and set a new UpdateFunc value.
func Update() bool {
return global.Update()
}
// Golden handles all interactions with golden files. The top-level package
// functions all just proxy through to a default global *Golden instance.
type Golden struct {
// DirMode determines the file system permissions of any folders created to
// hold golden files.
DirMode os.FileMode
// FileMode determines the file system permissions of any created or updated
// golden files written to disk.
FileMode os.FileMode
// Suffix determines the filename suffix for all golden files. Typically
// this should be ".golden", but can be changed here if needed.
Suffix string
// Dirname is the name of the top-level directory at the root of the package
// which holds all golden files. Typically this should "testdata", but can
// be changed here if needed.
Dirname string
// UpdateFunc is used to determine if golden files should be updated or
// not. Its boolean return value is returned by Update().
UpdateFunc UpdateFunc
}
// New returns a new *Golden instance with default values correctly
// populated. This is ideally how you should create a custom *Golden, and then
// modify the relevant fields as you see fit.
func New() *Golden {
return &Golden{
DirMode: DefaultDirMode,
FileMode: DefaultFileMode,
Suffix: DefaultSuffix,
Dirname: DefaultDirname,
UpdateFunc: DefaultUpdateFunc,
}
}
// File returns the filename of the golden file for the given *testing.T
// instance as determined by t.Name().
func (s *Golden) File(t *testing.T) string {
return s.file(t, "")
}
// Get returns the content of the golden file for the given *testing.T instance
// as determined by t.Name(). If no golden file can be found/read, it will fail
// the test by calling t.Fatal().
func (s *Golden) Get(t *testing.T) []byte {
return s.get(t, "")
}
// Set writes given data to the golden file for the given *testing.T instance as
// determined by t.Name(). If writing fails it will fail the test by calling
// t.Fatal() with error details.
func (s *Golden) Set(t *testing.T, data []byte) {
s.set(t, "", data)
}
// FileP returns the filename of the specifically named golden file for the
// given *testing.T instance as determined by t.Name().
func (s *Golden) FileP(t *testing.T, name string) string {
if name == "" {
if t != nil {
t.Fatal("golden: name cannot be empty")
}
return ""
}
return s.file(t, name)
}
// GetP returns the content of the specifically named golden file belonging
// to the given *testing.T instance as determined by t.Name(). If no golden file
// can be found/read, it will fail the test with t.Fatal().
//
// This is very similar to Get(), but it allows multiple different golden files
// to be used within the same one *testing.T instance.
func (s *Golden) GetP(t *testing.T, name string) []byte {
if name == "" {
t.Fatal("golden: name cannot be empty")
return nil
}
return s.get(t, name)
}
// SetP writes given data of the specifically named golden file belonging to
// the given *testing.T instance as determined by t.Name(). If writing fails it
// will fail the test with t.Fatal() detailing the error.
//
// This is very similar to Set(), but it allows multiple different golden files
// to be used within the same one *testing.T instance.
func (s *Golden) SetP(t *testing.T, name string, data []byte) {
if name == "" {
t.Fatal("golden: name cannot be empty")
}
s.set(t, name, data)
}
func (s *Golden) file(t *testing.T, name string) string {
if t.Name() == "" {
t.Fatalf("golden: could not determine filename for: %+v", t)
return ""
}
base := []string{s.Dirname, filepath.FromSlash(t.Name())}
if name != "" {
base = append(base, name)
}
f := filepath.Clean(filepath.Join(base...) + s.Suffix)
dirty := strings.Split(f, string(os.PathSeparator))
clean := make([]string, 0, len(dirty))
for _, s := range dirty {
clean = append(clean, sanitizeFilename(s))
}
return strings.Join(clean, string(os.PathSeparator))
}
func (s *Golden) get(t *testing.T, name string) []byte {
f := s.file(t, name)
b, err := ioutil.ReadFile(f)
if err != nil {
t.Fatalf("golden: failed reading %s: %s", f, err.Error())
}
return b
}
func (s *Golden) set(t *testing.T, name string, data []byte) {
f := s.file(t, name)
dir := filepath.Dir(f)
t.Logf("golden: writing .golden file: %s", f)
err := os.MkdirAll(dir, s.DirMode)
if err != nil {
t.Fatalf("golden: failed to create directory: %s", err.Error())
return
}
err = ioutil.WriteFile(f, data, s.FileMode)
if err != nil {
t.Fatalf("golden: filed to write file: %s", err.Error())
}
}
// Update returns true when golden is set to update golden files. Should be used
// to determine if golden.Set() or golden.SetP() should be called or not.
//
// Default behavior uses EnvUpdateFunc() to check if the "GOLDEN_UPDATE"
// environment variable is set to a truthy value. To customize set a new
// UpdateFunc value on *Golden.
func (s *Golden) Update() bool {
return s.UpdateFunc()
}