Merge pull request #1 from jimeh/refactor-things

refactor: get closer to "stable"

.github/workflows/ci.yml

@@ -32,6 +32,32 @@ jobs:
       - name: Check if mods are tidy
         run: make check-tidy
 
+  cov:
+    name: Coverage
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-go@v2
+        with:
+          go-version: 1.15
+      - uses: actions/cache@v2
+        with:
+          path: ~/go/pkg/mod
+          key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
+          restore-keys: |
+            ${{ runner.os }}-go-
+      - name: Publish coverage
+        uses: paambaati/codeclimate-action@v2.7.4
+        env:
+          VERBOSE: "true"
+          GOMAXPROCS: 4
+          CC_TEST_REPORTER_ID: ${{ secrets.CC_TEST_REPORTER_ID }}
+        with:
+          coverageCommand: make cov
+          prefix: github.com/${{ github.repository }}
+          coverageLocations: |
+            ${{ github.workspace }}/coverage.out:gocov
+
   test:
     name: Test
     strategy:

.gitignore

@@ -1,3 +1,5 @@
 bin/*
-testdata/*
 coverage.out
+
+testdata/*
+!testdata/TestExample*

Makefile

@@ -88,6 +88,18 @@ format: $(TOOLDIR)/goimports $(TOOLDIR)/gofumpt
 bench:
 	go test $(V) -count=1 -bench=$(BENCH) $(TESTARGS) ./...
 
+.PHONY: golden-update
+golden-update:
+	GOLDEN_UPDATE=1 $(MAKE) test
+
+.PHONY: golden-clean
+golden-clean:
+	find . -type f -name '*.golden' -path '*/testdata/*' -delete
+	find . -type d -empty -path '*/testdata/*' -delete
+
+.PHONY: golden-regen
+golden-regen: golden-clean golden-update
+
 #
 # Code Generation
 #
@@ -171,7 +183,7 @@ check-tidy:
 
 # Serve docs
 .PHONY: docs
-docs: godoc
+docs: $(TOOLDIR)/godoc
 	$(info serviing docs on http://127.0.0.1:6060/pkg/$(GOMODNAME)/)
 	@godoc -http=127.0.0.1:6060
 

README.md

@@ -1,5 +1,80 @@
-# go-golden
+<h1 align="center">
+  go-golden
+</h1>
 
-Yet another Go package for working with `*.golden` test files.
+<p align="center">
+  <strong>
+    Yet another Go package for working with `*.golden` test files, with a focus
+    on simplicity through it's default behavior.
+  </strong>
+</p>
 
-Currently a work in progress.
+<p align="center">
+  <a href="https://pkg.go.dev/github.com/jimeh/go-golden">
+    <img src="https://img.shields.io/badge/%E2%80%8B-reference-387b97.svg?logo=go&logoColor=white"
+  alt="Go Reference">
+  </a>
+  <a href="https://github.com/jimeh/go-golden/actions">
+    <img src="https://img.shields.io/github/workflow/status/jimeh/go-golden/CI.svg?logo=github" alt="Actions Status">
+  </a>
+  <a href="https://codeclimate.com/github/jimeh/go-golden">
+    <img src="https://img.shields.io/codeclimate/coverage/jimeh/go-golden.svg?logo=code%20climate" alt="Coverage">
+  </a>
+  <a href="https://github.com/jimeh/go-golden/issues">
+    <img src="https://img.shields.io/github/issues-raw/jimeh/go-golden.svg?style=flat&logo=github&logoColor=white"
+alt="GitHub issues">
+  </a>
+  <a href="https://github.com/jimeh/go-golden/pulls">
+    <img src="https://img.shields.io/github/issues-pr-raw/jimeh/go-golden.svg?style=flat&logo=github&logoColor=white" alt="GitHub pull requests">
+  </a>
+  <a href="https://github.com/jimeh/go-golden/blob/master/LICENSE">
+    <img src="https://img.shields.io/github/license/jimeh/go-golden.svg?style=flat" alt="License Status">
+  </a>
+</p>
+
+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.
+
+## Import
+
+```
+import "github.com/jimeh/go-golden"
+```
+
+## Usage
+
+Typical usage should look something like this:
+
+```go
+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.
+
+## Documentation
+
+Please see the
+[Go Reference](https://pkg.go.dev/github.com/jimeh/go-golden#section-documentation)
+for documentation and examples.
+
+## License
+
+[MIT](https://github.com/jimeh/go-golden/blob/master/LICENSE)

example_test.go

@@ -0,0 +1,108 @@
+package golden_test
+
+import (
+	"encoding/json"
+	"encoding/xml"
+	"testing"
+
+	"github.com/jimeh/go-golden"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+type MyStruct struct {
+	Foo string `json:"foo,omitempty"`
+}
+
+// TestExampleMyStruct reads/writes the following golden file:
+//
+//  testdata/TestExampleMyStruct.golden
+//
+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)
+}
+
+// TestExampleMyStructTabular reads/writes the following golden files:
+//
+//  testdata/TestExampleMyStructTabular/empty_struct.golden
+//  testdata/TestExampleMyStructTabular/full_struct.golden
+//
+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)
+		})
+	}
+}
+
+// TestExampleMyStructP reads/writes the following golden file:
+//
+//  testdata/TestExampleMyStructP/json.golden
+//  testdata/TestExampleMyStructP/xml.golden
+//
+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)
+}
+
+// TestExampleMyStructTabularP reads/writes the following golden file:
+//
+//  testdata/TestExampleMyStructTabularP/empty_struct/json.golden
+//  testdata/TestExampleMyStructTabularP/empty_struct/xml.golden
+//  testdata/TestExampleMyStructTabularP/full_struct/json.golden
+//  testdata/TestExampleMyStructTabularP/full_struct/xml.golden
+//
+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)
+		})
+	}
+}

global.go

@@ -1,49 +0,0 @@
-package golden
-
-import "testing"
-
-var global = New()
-
-// Updating returns true when golden is set to update golden files. Used to
-// determine if golden.Set() should be called or not.
-func Updating() bool {
-	return global.Updating()
-}
-
-// Get returns the content of the default 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 with t.Fatal().
-func Get(t *testing.T) []byte {
-	return global.Get(t)
-}
-
-// Set writes given data of the default golden file for the given *testing.T
-// instance as determined by t.Name(). If writing fails it will fail the test
-// with t.Fatal() detailing the error.
-func Set(t *testing.T, data []byte) {
-	global.Set(t, data)
-}
-
-// File returns the filename for the default golden file for the given
-// *testing.T instance as determined by t.Name().
-func File(t *testing.T) string {
-	return global.File(t)
-}
-
-// GetNamed return 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().
-func GetNamed(t *testing.T, name string) []byte {
-	return global.GetNamed(t, name)
-}
-
-// SetNamed 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.
-func SetNamed(t *testing.T, name string, data []byte) {
-	global.SetNamed(t, name, data)
-}
-
-func NamedFile(t *testing.T, name string) string {
-	return global.NamedFile(t, name)
-}

golden.go

@@ -1,10 +1,132 @@
-// Package golden is yet another package for working with *.golden test files.
+// 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"
 )
 
@@ -15,54 +137,190 @@ const (
 	DefaultDirname  = "testdata"
 )
 
-type Golden struct {
-	DirMode      os.FileMode
-	FileMode     os.FileMode
-	Suffix       string
-	Dirname      string
-	UpdatingFunc UpdatingFunc
+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 {
+	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 {
+	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) {
+	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 {
+	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 {
+	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) {
+	global.SetP(t, name, data)
+}
+
+// Update returns true when golden is set to update golden files. Used to
+// determine if golden.Set() or golden.Write() 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,
-		UpdatingFunc: EnvVarUpdatingFunc,
+		DirMode:    DefaultDirMode,
+		FileMode:   DefaultFileMode,
+		Suffix:     DefaultSuffix,
+		Dirname:    DefaultDirname,
+		UpdateFunc: DefaultUpdateFunc,
 	}
 }
 
-// Updating returns true when the function assigned to UpdatingFunc returns
-// true.
-func (s *Golden) Updating() bool {
-	return s.UpdatingFunc()
-}
-
-// Get returns the content of the default 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 with t.Fatal().
-func (s *Golden) Get(t *testing.T) []byte {
-	return s.GetNamed(t, "")
-}
-
-// Set writes given data of the default golden file for the given *testing.T
-// instance as determined by t.Name(). If writing fails it will fail the test
-// with t.Fatal() detailing the error.
-func (s *Golden) Set(t *testing.T, data []byte) {
-	s.SetNamed(t, "", data)
-}
-
+// 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.NamedFile(t, "")
+	return s.file(t, "")
 }
 
-func (s *Golden) GetNamed(t *testing.T, name string) []byte {
-	if t == nil {
+// 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
 	}
 
-	f := s.NamedFile(t, name)
+	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 {
@@ -72,12 +330,8 @@ func (s *Golden) GetNamed(t *testing.T, name string) []byte {
 	return b
 }
 
-func (s *Golden) SetNamed(t *testing.T, name string, data []byte) {
-	if t == nil {
-		return
-	}
-
-	f := s.NamedFile(t, name)
+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)
@@ -94,16 +348,12 @@ func (s *Golden) SetNamed(t *testing.T, name string, data []byte) {
 	}
 }
 
-func (s *Golden) NamedFile(t *testing.T, name string) string {
-	if t == nil || 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)
-	}
-
-	return filepath.Clean(filepath.Join(base...) + s.Suffix)
+// Update returns true when golden is set to update golden files. Used to
+// determine if golden.Set() or golden.Write() 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()
 }

golden_test.go

@@ -11,98 +11,6 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-func TestUpdating(t *testing.T) {
-	tests := []struct {
-		name string
-		env  map[string]string
-		want bool
-	}{
-		{
-			name: "GOLDEN_UPDATE not set",
-			want: false,
-		},
-		{
-			name: "GOLDEN_UPDATE set to 0",
-			env:  map[string]string{"GOLDEN_UPDATE": "0"},
-			want: false,
-		},
-		{
-			name: "GOLDEN_UPDATE set to 1",
-			env:  map[string]string{"GOLDEN_UPDATE": "1"},
-			want: true,
-		},
-		{
-			name: "GOLDEN_UPDATE set to 2",
-			env:  map[string]string{"GOLDEN_UPDATE": "2"},
-			want: false,
-		},
-		{
-			name: "GOLDEN_UPDATE set to y",
-			env:  map[string]string{"GOLDEN_UPDATE": "y"},
-			want: true,
-		},
-		{
-			name: "GOLDEN_UPDATE set to n",
-			env:  map[string]string{"GOLDEN_UPDATE": "n"},
-			want: false,
-		},
-		{
-			name: "GOLDEN_UPDATE set to t",
-			env:  map[string]string{"GOLDEN_UPDATE": "t"},
-			want: true,
-		},
-		{
-			name: "GOLDEN_UPDATE set to f",
-			env:  map[string]string{"GOLDEN_UPDATE": "f"},
-			want: false,
-		},
-		{
-			name: "GOLDEN_UPDATE set to yes",
-			env:  map[string]string{"GOLDEN_UPDATE": "yes"},
-			want: true,
-		},
-		{
-			name: "GOLDEN_UPDATE set to no",
-			env:  map[string]string{"GOLDEN_UPDATE": "no"},
-			want: false,
-		},
-		{
-			name: "GOLDEN_UPDATE set to on",
-			env:  map[string]string{"GOLDEN_UPDATE": "on"},
-			want: true,
-		},
-		{
-			name: "GOLDEN_UPDATE set to off",
-			env:  map[string]string{"GOLDEN_UPDATE": "off"},
-			want: false,
-		},
-		{
-			name: "GOLDEN_UPDATE set to true",
-			env:  map[string]string{"GOLDEN_UPDATE": "true"},
-			want: true,
-		},
-		{
-			name: "GOLDEN_UPDATE set to false",
-			env:  map[string]string{"GOLDEN_UPDATE": "false"},
-			want: false,
-		},
-		{
-			name: "GOLDEN_UPDATE set to foobarnopebbq",
-			env:  map[string]string{"GOLDEN_UPDATE": "foobarnopebbq"},
-			want: false,
-		},
-	}
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			envctl.WithClean(tt.env, func() {
-				got := Updating()
-
-				assert.Equal(t, tt.want, got)
-			})
-		})
-	}
-}
-
 func TestFile(t *testing.T) {
 	got := File(t)
 
@@ -122,11 +30,11 @@ func TestFile(t *testing.T) {
 		},
 		{
 			name: "foo/bar",
-			want: filepath.Join("testdata", "TestFile", "foo/bar.golden"),
+			want: filepath.Join("testdata", "TestFile", "foo", "bar.golden"),
 		},
 		{
 			name: `"foobar"`,
-			want: filepath.Join("testdata", "TestFile", "\"foobar\".golden"),
+			want: filepath.Join("testdata", "TestFile", "_foobar_.golden"),
 		},
 	}
 	for _, tt := range tests {
@@ -140,9 +48,9 @@ func TestFile(t *testing.T) {
 
 func TestGet(t *testing.T) {
 	t.Cleanup(func() {
-		err := os.RemoveAll(filepath.Join("testdata", t.Name()))
+		err := os.RemoveAll(filepath.Join("testdata", "TestGet"))
 		require.NoError(t, err)
-		err = os.Remove(filepath.Join("testdata", t.Name()+".golden"))
+		err = os.Remove(filepath.Join("testdata", "TestGet.golden"))
 		require.NoError(t, err)
 	})
 
@@ -188,7 +96,7 @@ func TestGet(t *testing.T) {
 		{
 			name: "thing: it's a thing!",
 			file: filepath.Join(
-				"testdata", "TestGet", "thing:_it's_a_thing!.golden",
+				"testdata", "TestGet", "thing__it's_a_thing!.golden",
 			),
 			want: []byte("A thing? Really? Are we getting lazy? :P"),
 		},
@@ -214,9 +122,9 @@ func TestGet(t *testing.T) {
 
 func TestSet(t *testing.T) {
 	t.Cleanup(func() {
-		err := os.RemoveAll(filepath.Join("testdata", t.Name()))
+		err := os.RemoveAll(filepath.Join("testdata", "TestSet"))
 		require.NoError(t, err)
-		err = os.Remove(filepath.Join("testdata", t.Name()+".golden"))
+		err = os.Remove(filepath.Join("testdata", "TestSet.golden"))
 		require.NoError(t, err)
 	})
 
@@ -258,7 +166,7 @@ func TestSet(t *testing.T) {
 		{
 			name: "thing: it's a thing!",
 			file: filepath.Join(
-				"testdata", "TestSet", "thing:_it's_a_thing!.golden",
+				"testdata", "TestSet", "thing__it's_a_thing!.golden",
 			),
 			content: []byte("A thing? Really? Are we getting lazy? :P"),
 		},
@@ -278,34 +186,74 @@ func TestSet(t *testing.T) {
 	}
 }
 
-func TestGetNamed(t *testing.T) {
+func TestFileP(t *testing.T) {
+	got := FileP(t, "sub-name")
+	assert.Equal(t,
+		filepath.Join("testdata", "TestFileP", "sub-name.golden"), got,
+	)
+
+	tests := []struct {
+		name  string
+		named string
+		want  string
+	}{
+		{
+			name:  "",
+			named: "sub-thing",
+			want: filepath.Join(
+				"testdata", "TestFileP", "#00", "sub-thing.golden",
+			),
+		},
+		{
+			name:  "fozbaz",
+			named: "email",
+			want: filepath.Join(
+				"testdata", "TestFileP", "fozbaz", "email.golden",
+			),
+		},
+		{
+			name:  "fozbaz",
+			named: "json",
+			want: filepath.Join(
+				"testdata", "TestFileP", "fozbaz#01", "json.golden",
+			),
+		},
+		{
+			name:  "foo/bar",
+			named: "hello/world",
+			want: filepath.Join(
+				"testdata", "TestFileP",
+				"foo", "bar",
+				"hello", "world.golden",
+			),
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := FileP(t, tt.named)
+
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}
+
+func TestGetP(t *testing.T) {
 	t.Cleanup(func() {
-		err := os.RemoveAll(filepath.Join("testdata", t.Name()))
-		require.NoError(t, err)
-		err = os.Remove(filepath.Join("testdata", t.Name()+".golden"))
+		err := os.RemoveAll(filepath.Join("testdata", "TestGetP"))
 		require.NoError(t, err)
 	})
 
-	err := os.MkdirAll(filepath.Join("testdata", "TestGetNamed"), 0o755)
+	err := os.MkdirAll(filepath.Join("testdata", "TestGetP"), 0o755)
 	require.NoError(t, err)
 
-	content := []byte("this is the default golden file for TestGetNamed")
+	content := []byte("this is the named golden file for TestGetP")
 	err = ioutil.WriteFile( //nolint:gosec
-		filepath.Join("testdata", "TestGetNamed.golden"), content, 0o644,
-	)
-	require.NoError(t, err)
-
-	got := GetNamed(t, "")
-	assert.Equal(t, content, got)
-
-	content = []byte("this is the named golden file for TestGetNamed")
-	err = ioutil.WriteFile( //nolint:gosec
-		filepath.Join("testdata", "TestGetNamed", "sub-name.golden"),
+		filepath.Join("testdata", "TestGetP", "sub-name.golden"),
 		content, 0o644,
 	)
 	require.NoError(t, err)
 
-	got = GetNamed(t, "sub-name")
+	got := GetP(t, "sub-name")
 	assert.Equal(t, content, got)
 
 	tests := []struct {
@@ -314,16 +262,11 @@ func TestGetNamed(t *testing.T) {
 		file  string
 		want  []byte
 	}{
-		{
-			name: "",
-			file: filepath.Join("testdata", "TestGetNamed", "#00.golden"),
-			want: []byte("number double-zero here"),
-		},
 		{
 			name:  "",
 			named: "sub-zero-one",
 			file: filepath.Join(
-				"testdata", "TestGetNamed", "#01/sub-zero-one.golden",
+				"testdata", "TestGetP", "#00", "sub-zero-one.golden",
 			),
 			want: []byte("number zero-one here"),
 		},
@@ -331,7 +274,7 @@ func TestGetNamed(t *testing.T) {
 			name:  "foobar",
 			named: "email",
 			file: filepath.Join(
-				"testdata", "TestGetNamed", "foobar/email.golden",
+				"testdata", "TestGetP", "foobar", "email.golden",
 			),
 			want: []byte("foobar email here"),
 		},
@@ -339,7 +282,7 @@ func TestGetNamed(t *testing.T) {
 			name:  "foobar",
 			named: "json",
 			file: filepath.Join(
-				"testdata", "TestGetNamed", "foobar#01/json.golden",
+				"testdata", "TestGetP", "foobar#01", "json.golden",
 			),
 			want: []byte("foobar json here"),
 		},
@@ -347,7 +290,7 @@ func TestGetNamed(t *testing.T) {
 			name:  "foo/bar",
 			named: "hello/world",
 			file: filepath.Join(
-				"testdata", "TestGetNamed",
+				"testdata", "TestGetP",
 				"foo", "bar",
 				"hello", "world.golden",
 			),
@@ -357,7 +300,7 @@ func TestGetNamed(t *testing.T) {
 			name:  "john's lost flip-flop",
 			named: "left",
 			file: filepath.Join(
-				"testdata", "TestGetNamed", "john's_lost_flip-flop",
+				"testdata", "TestGetP", "john's_lost_flip-flop",
 				"left.golden",
 			),
 			want: []byte("Did John lose his left flip-flop again?"),
@@ -366,7 +309,7 @@ func TestGetNamed(t *testing.T) {
 			name:  "john's lost flip-flop",
 			named: "right",
 			file: filepath.Join(
-				"testdata", "TestGetNamed", "john's_lost_flip-flop#01",
+				"testdata", "TestGetP", "john's_lost_flip-flop#01",
 				"right.golden",
 			),
 			want: []byte("Did John lose his right flip-flop again?"),
@@ -375,14 +318,14 @@ func TestGetNamed(t *testing.T) {
 			name:  "thing: it's",
 			named: "a thing!",
 			file: filepath.Join(
-				"testdata", "TestGetNamed", "thing:_it's", "a thing!.golden",
+				"testdata", "TestGetP", "thing__it's", "a_thing!.golden",
 			),
 			want: []byte("A thing? Really? Are we getting lazy? :P"),
 		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			f := NamedFile(t, tt.named)
+			f := FileP(t, tt.named)
 			dir := filepath.Dir(f)
 
 			err := os.MkdirAll(dir, 0o755)
@@ -391,7 +334,7 @@ func TestGetNamed(t *testing.T) {
 			err = ioutil.WriteFile(f, tt.want, 0o644) //nolint:gosec
 			require.NoError(t, err)
 
-			got := GetNamed(t, tt.named)
+			got := GetP(t, tt.named)
 
 			assert.Equal(t, filepath.FromSlash(tt.file), f)
 			assert.Equal(t, tt.want, got)
@@ -399,27 +342,17 @@ func TestGetNamed(t *testing.T) {
 	}
 }
 
-func TestSetNamed(t *testing.T) {
+func TestSetP(t *testing.T) {
 	t.Cleanup(func() {
-		err := os.RemoveAll(filepath.Join("testdata", t.Name()))
-		require.NoError(t, err)
-		err = os.Remove(filepath.Join("testdata", t.Name()+".golden"))
+		err := os.RemoveAll(filepath.Join("testdata", "TestSetP"))
 		require.NoError(t, err)
 	})
 
-	content := []byte("This is the default golden file for TestSetNamed ^_^")
-	SetNamed(t, "", content)
+	content := []byte("This is the named golden file for TestSetP ^_^")
+	SetP(t, "sub-name", content)
 
-	b, err := ioutil.ReadFile(filepath.Join("testdata", "TestSetNamed.golden"))
-	require.NoError(t, err)
-
-	assert.Equal(t, content, b)
-
-	content = []byte("This is the named golden file for TestSetNamed ^_^")
-	SetNamed(t, "sub-name", content)
-
-	b, err = ioutil.ReadFile(
-		filepath.Join("testdata", "TestSetNamed", "sub-name.golden"),
+	b, err := ioutil.ReadFile(
+		filepath.Join("testdata", "TestSetP", "sub-name.golden"),
 	)
 	require.NoError(t, err)
 
@@ -431,16 +364,11 @@ func TestSetNamed(t *testing.T) {
 		file    string
 		content []byte
 	}{
-		{
-			name:    "",
-			file:    filepath.Join("testdata", "TestSetNamed", "#00.golden"),
-			content: []byte("number double-zero strikes again"),
-		},
 		{
 			name:  "",
 			named: "sub-zero-one",
 			file: filepath.Join(
-				"testdata", "TestSetNamed", "#01", "sub-zero-one.golden",
+				"testdata", "TestSetP", "#00", "sub-zero-one.golden",
 			),
 			content: []byte("number zero-one sub-zero-one strikes again"),
 		},
@@ -448,7 +376,7 @@ func TestSetNamed(t *testing.T) {
 			name:  "foobar",
 			named: "email",
 			file: filepath.Join(
-				"testdata", "TestSetNamed", "foobar", "email.golden",
+				"testdata", "TestSetP", "foobar", "email.golden",
 			),
 			content: []byte("foobar here"),
 		},
@@ -456,22 +384,15 @@ func TestSetNamed(t *testing.T) {
 			name:  "foobar",
 			named: "json",
 			file: filepath.Join(
-				"testdata", "TestSetNamed", "foobar#01", "json.golden",
+				"testdata", "TestSetP", "foobar#01", "json.golden",
 			),
 			content: []byte("foobar here"),
 		},
-		{
-			name: "foo/bar",
-			file: filepath.Join(
-				"testdata", "TestSetNamed", "foo", "bar.golden",
-			),
-			content: []byte("foo/bar style sub-sub-folders works too"),
-		},
 		{
 			name:  "john's lost flip-flop",
 			named: "left",
 			file: filepath.Join(
-				"testdata", "TestSetNamed", "john's_lost_flip-flop",
+				"testdata", "TestSetP", "john's_lost_flip-flop",
 				"left.golden",
 			),
 			content: []byte("Did John lose his left flip-flop again?"),
@@ -480,7 +401,7 @@ func TestSetNamed(t *testing.T) {
 			name:  "john's lost flip-flop",
 			named: "right",
 			file: filepath.Join(
-				"testdata", "TestSetNamed", "john's_lost_flip-flop#01",
+				"testdata", "TestSetP", "john's_lost_flip-flop#01",
 				"right.golden",
 			),
 			content: []byte("Did John lose his right flip-flop again?"),
@@ -489,16 +410,16 @@ func TestSetNamed(t *testing.T) {
 			name:  "thing: it's",
 			named: "a thing!",
 			file: filepath.Join(
-				"testdata", "TestSetNamed", "thing:_it's", "a thing!.golden",
+				"testdata", "TestSetP", "thing__it's", "a_thing!.golden",
 			),
 			content: []byte("A thing? Really? Are we getting lazy? :P"),
 		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			f := NamedFile(t, tt.named)
+			f := FileP(t, tt.named)
 
-			SetNamed(t, tt.named, tt.content)
+			SetP(t, tt.named, tt.content)
 
 			got, err := ioutil.ReadFile(f)
 			require.NoError(t, err)
@@ -509,53 +430,14 @@ func TestSetNamed(t *testing.T) {
 	}
 }
 
-func TestNamedFile(t *testing.T) {
-	got := NamedFile(t, "")
-	assert.Equal(t, "testdata/TestNamedFile.golden", got)
-
-	got = NamedFile(t, "sub-name")
-	assert.Equal(t, "testdata/TestNamedFile/sub-name.golden", got)
-
-	tests := []struct {
-		name  string
-		named string
-		want  string
-	}{
-		{
-			name:  "",
-			named: "",
-			want:  "testdata/TestNamedFile/#00.golden",
-		},
-		{
-			name:  "",
-			named: "sub-thing",
-			want:  "testdata/TestNamedFile/#01/sub-thing.golden",
-		},
-		{
-			name: "foobar",
-			want: "testdata/TestNamedFile/foobar.golden",
-		},
-		{
-			name:  "fozbaz",
-			named: "email",
-			want:  "testdata/TestNamedFile/fozbaz/email.golden",
-		},
-		{
-			name:  "fozbaz",
-			named: "json",
-			want:  "testdata/TestNamedFile/fozbaz#01/json.golden",
-		},
-		{
-			name:  "foo/bar",
-			named: "hello/world",
-			want:  "testdata/TestNamedFile/foo/bar/hello/world.golden",
-		},
-	}
-	for _, tt := range tests {
+func TestUpdate(t *testing.T) {
+	for _, tt := range envUpdateFuncTestCases {
 		t.Run(tt.name, func(t *testing.T) {
-			got := NamedFile(t, tt.named)
+			envctl.WithClean(tt.env, func() {
+				got := Update()
 
-			assert.Equal(t, tt.want, got)
+				assert.Equal(t, tt.want, got)
+			})
 		})
 	}
 }

sanitize.go

@@ -0,0 +1,34 @@
+package golden
+
+import (
+	"regexp"
+	"strings"
+)
+
+var (
+	whitespaceChars = regexp.MustCompile(`\s`)
+	illegalChars    = regexp.MustCompile(`[\/\?<>\\:\*\|"]`)
+	controlChars    = regexp.MustCompile(`[\x00-\x1f\x80-\x9f]`)
+	reservedNames   = regexp.MustCompile(`^\.+$`)
+	winReserved     = regexp.MustCompile(
+		`(?i)^(con|prn|aux|nul|com[0-9]|lpt[0-9])(\..*)?$`,
+	)
+)
+
+func sanitizeFilename(name string) string {
+	if reservedNames.MatchString(name) || winReserved.MatchString(name) {
+		var b []byte
+		for i := 0; i < len(name); i++ {
+			b = append(b, byte('_'))
+		}
+
+		return string(b)
+	}
+
+	r := strings.TrimRight(name, ". ")
+	r = whitespaceChars.ReplaceAllString(r, "_")
+	r = illegalChars.ReplaceAllString(r, "_")
+	r = controlChars.ReplaceAllString(r, "_")
+
+	return r
+}

sanitize_test.go

@@ -0,0 +1,124 @@
+package golden
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_sanitizeFilename(t *testing.T) {
+	tests := []struct {
+		name     string
+		filename string
+		want     string
+	}{
+		{
+			name:     "empty",
+			filename: "",
+			want:     "",
+		},
+		{
+			name:     ".",
+			filename: ".",
+			want:     "_",
+		},
+		{
+			name:     "..",
+			filename: "..",
+			want:     "__",
+		},
+		{
+			name:     "...",
+			filename: "...",
+			want:     "___",
+		},
+		{
+			name:     "clean",
+			filename: "foo-bar-nope.golden",
+			want:     "foo-bar-nope.golden",
+		},
+		{
+			name:     "with spaces",
+			filename: "foo  bar nope.golden",
+			want:     "foo__bar_nope.golden",
+		},
+		{
+			name:     "illegal chars",
+			filename: `foo/?<>\:*|"bar.golden`,
+			want:     "foo_________bar.golden",
+		},
+		{
+			name: "control chars",
+			filename: "foo\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b" +
+				"\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a" +
+				"\x1b\x1c\x1d\x1e\x1fbar.golden",
+			want: "foo________________________________bar.golden",
+		},
+		{
+			name:     "trailing whitespace",
+			filename: "foobar.golden    ",
+			want:     "foobar.golden",
+		},
+		{
+			name:     "trailing dots",
+			filename: "foobar.golden......",
+			want:     "foobar.golden",
+		},
+		{
+			name:     "trailing whitespace and dots",
+			filename: "foobar.golden  ..  ..  ..  ",
+			want:     "foobar.golden",
+		},
+		{name: "con", filename: "con", want: "___"},
+		{name: "prn", filename: "prn", want: "___"},
+		{name: "aux", filename: "aux", want: "___"},
+		{name: "nul", filename: "nul", want: "___"},
+		{name: "com1", filename: "com1", want: "____"},
+		{name: "com2", filename: "com2", want: "____"},
+		{name: "com3", filename: "com3", want: "____"},
+		{name: "com4", filename: "com4", want: "____"},
+		{name: "com5", filename: "com5", want: "____"},
+		{name: "com6", filename: "com6", want: "____"},
+		{name: "com7", filename: "com7", want: "____"},
+		{name: "com8", filename: "com8", want: "____"},
+		{name: "com9", filename: "com9", want: "____"},
+		{name: "lpt1", filename: "lpt1", want: "____"},
+		{name: "lpt2", filename: "lpt2", want: "____"},
+		{name: "lpt3", filename: "lpt3", want: "____"},
+		{name: "lpt4", filename: "lpt4", want: "____"},
+		{name: "lpt5", filename: "lpt5", want: "____"},
+		{name: "lpt6", filename: "lpt6", want: "____"},
+		{name: "lpt7", filename: "lpt7", want: "____"},
+		{name: "lpt8", filename: "lpt8", want: "____"},
+		{name: "lpt9", filename: "lpt9", want: "____"},
+		{name: "CON", filename: "CON", want: "___"},
+		{name: "PRN", filename: "PRN", want: "___"},
+		{name: "AUX", filename: "AUX", want: "___"},
+		{name: "NUL", filename: "NUL", want: "___"},
+		{name: "COM1", filename: "COM1", want: "____"},
+		{name: "COM2", filename: "COM2", want: "____"},
+		{name: "COM3", filename: "COM3", want: "____"},
+		{name: "COM4", filename: "COM4", want: "____"},
+		{name: "COM5", filename: "COM5", want: "____"},
+		{name: "COM6", filename: "COM6", want: "____"},
+		{name: "COM7", filename: "COM7", want: "____"},
+		{name: "COM8", filename: "COM8", want: "____"},
+		{name: "COM9", filename: "COM9", want: "____"},
+		{name: "LPT1", filename: "LPT1", want: "____"},
+		{name: "LPT2", filename: "LPT2", want: "____"},
+		{name: "LPT3", filename: "LPT3", want: "____"},
+		{name: "LPT4", filename: "LPT4", want: "____"},
+		{name: "LPT5", filename: "LPT5", want: "____"},
+		{name: "LPT6", filename: "LPT6", want: "____"},
+		{name: "LPT7", filename: "LPT7", want: "____"},
+		{name: "LPT8", filename: "LPT8", want: "____"},
+		{name: "LPT9", filename: "LPT9", want: "____"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := sanitizeFilename(tt.filename)
+
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}

testdata/TestExampleMyStruct.golden

@@ -0,0 +1 @@
+{"foo":"Bar"}

testdata/TestExampleMyStructP/json.golden

@@ -0,0 +1 @@
+{"foo":"Bar"}

testdata/TestExampleMyStructP/xml.golden

@@ -0,0 +1 @@
+<MyStruct><Foo>Bar</Foo></MyStruct>

testdata/TestExampleMyStructTabular/empty_struct.golden

@@ -0,0 +1 @@
+{}

testdata/TestExampleMyStructTabular/full_struct.golden

@@ -0,0 +1 @@
+{"foo":"Bar"}

testdata/TestExampleMyStructTabularP/empty_struct/json.golden

@@ -0,0 +1 @@
+{}

testdata/TestExampleMyStructTabularP/empty_struct/xml.golden

@@ -0,0 +1 @@
+<MyStruct><Foo></Foo></MyStruct>

testdata/TestExampleMyStructTabularP/full_struct/json.golden

@@ -0,0 +1 @@
+{"foo":"Bar"}

testdata/TestExampleMyStructTabularP/full_struct/xml.golden

@@ -0,0 +1 @@
+<MyStruct><Foo>Bar</Foo></MyStruct>

update.go

@@ -4,11 +4,14 @@ import "os"
 
 var truthyStrings = []string{"1", "y", "t", "yes", "on", "true"}
 
-type UpdatingFunc func() bool
+type UpdateFunc func() bool
 
-// EnvVarUpdateFunc checks if the GOLDEN_UPDATE environment variable is set to
+// EnvUpdateFunc checks if the GOLDEN_UPDATE environment variable is set to
 // one of "1", "y", "t", "yes", "on", or "true".
-func EnvVarUpdatingFunc() bool {
+//
+// This is also the default UpdateFunc used to determine the return value of
+// Update().
+func EnvUpdateFunc() bool {
 	env := os.Getenv("GOLDEN_UPDATE")
 	for _, v := range truthyStrings {
 		if env == v {

update_test.go

@@ -0,0 +1,106 @@
+package golden
+
+import (
+	"testing"
+
+	"github.com/jimeh/envctl"
+	"github.com/stretchr/testify/assert"
+)
+
+var envUpdateFuncTestCases = []struct {
+	name string
+	env  map[string]string
+	want bool
+}{
+	{
+		name: "GOLDEN_UPDATE not set",
+		want: false,
+	},
+	{
+		name: "GOLDEN_UPDATE set to empty string",
+		env:  map[string]string{"GOLDEN_UPDATE": ""},
+		want: false,
+	},
+	{
+		name: "GOLDEN_UPDATE set to 0",
+		env:  map[string]string{"GOLDEN_UPDATE": "0"},
+		want: false,
+	},
+	{
+		name: "GOLDEN_UPDATE set to 1",
+		env:  map[string]string{"GOLDEN_UPDATE": "1"},
+		want: true,
+	},
+	{
+		name: "GOLDEN_UPDATE set to 2",
+		env:  map[string]string{"GOLDEN_UPDATE": "2"},
+		want: false,
+	},
+	{
+		name: "GOLDEN_UPDATE set to y",
+		env:  map[string]string{"GOLDEN_UPDATE": "y"},
+		want: true,
+	},
+	{
+		name: "GOLDEN_UPDATE set to n",
+		env:  map[string]string{"GOLDEN_UPDATE": "n"},
+		want: false,
+	},
+	{
+		name: "GOLDEN_UPDATE set to t",
+		env:  map[string]string{"GOLDEN_UPDATE": "t"},
+		want: true,
+	},
+	{
+		name: "GOLDEN_UPDATE set to f",
+		env:  map[string]string{"GOLDEN_UPDATE": "f"},
+		want: false,
+	},
+	{
+		name: "GOLDEN_UPDATE set to yes",
+		env:  map[string]string{"GOLDEN_UPDATE": "yes"},
+		want: true,
+	},
+	{
+		name: "GOLDEN_UPDATE set to no",
+		env:  map[string]string{"GOLDEN_UPDATE": "no"},
+		want: false,
+	},
+	{
+		name: "GOLDEN_UPDATE set to on",
+		env:  map[string]string{"GOLDEN_UPDATE": "on"},
+		want: true,
+	},
+	{
+		name: "GOLDEN_UPDATE set to off",
+		env:  map[string]string{"GOLDEN_UPDATE": "off"},
+		want: false,
+	},
+	{
+		name: "GOLDEN_UPDATE set to true",
+		env:  map[string]string{"GOLDEN_UPDATE": "true"},
+		want: true,
+	},
+	{
+		name: "GOLDEN_UPDATE set to false",
+		env:  map[string]string{"GOLDEN_UPDATE": "false"},
+		want: false,
+	},
+	{
+		name: "GOLDEN_UPDATE set to foobarnopebbq",
+		env:  map[string]string{"GOLDEN_UPDATE": "foobarnopebbq"},
+		want: false,
+	},
+}
+
+func TestEnvUpdateFunc(t *testing.T) {
+	for _, tt := range envUpdateFuncTestCases {
+		t.Run(tt.name, func(t *testing.T) {
+			envctl.WithClean(tt.env, func() {
+				got := EnvUpdateFunc()
+
+				assert.Equal(t, tt.want, got)
+			})
+		})
+	}
+}