Refactor code fix deprecations and format

endtoend_test.go

@@ -5,15 +5,13 @@
 // go command is not available on android
 
 //go:build !android
-// +build !android
 
 package main
 
 import (
 	"fmt"
 	"go/build"
 	"io"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -22,11 +20,9 @@ import (
 	"testing"
 )
 
-var (
-	// GOEXE defines the executable file name suffix (".exe" on Windows, "" on other systems).
-	// Must be defined here, cannot be read from ENVIRONMENT variables
-	GOEXE = ""
-)
+// GOEXE defines the executable file name suffix (".exe" on Windows, "" on other systems).
+// Must be defined here, cannot be read from ENVIRONMENT variables
+var GOEXE = ""
 
 func init() {
 	// Set GOEXE for Windows platform
@@ -41,15 +37,11 @@ func init() {
 // binary panics if the String method for X is not correct, including for error cases.
 
 func TestEndToEnd(t *testing.T) {
-	dir, err := ioutil.TempDir("", "stringer")
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer os.RemoveAll(dir)
+	dir := t.TempDir()
 
 	// Create stringer in temporary directory.
 	stringer := filepath.Join(dir, fmt.Sprintf("stringer%s", GOEXE))
-	err = run("go", "build", "-o", stringer)
+	err := run("go", "build", "-o", stringer)
 	if err != nil {
 		t.Fatalf("building stringer: %s", err)
 	}

golden_test.go

@@ -21,7 +21,7 @@ import (
 type Golden struct {
 	name  string
 	input string // input; the package clause is provided when running the test.
-	//output string // expected output.
+	// output string // expected output.
 }
 
 var golden = []Golden{
@@ -36,6 +36,7 @@ var golden = []Golden{
 var goldenJSON = []Golden{
 	{"primeJson", primeJsonIn},
 }
+
 var goldenText = []Golden{
 	{"primeText", primeTextIn},
 }
@@ -457,19 +458,10 @@ func runGoldenTest(t *testing.T, test Golden, opts generateOptions) {
 	file := test.name + ".go"
 	input := "package test\n" + test.input
 
-	dir, err := os.MkdirTemp("", "stringer")
-	if err != nil {
-		t.Error(err)
-	}
-	defer func() {
-		err = os.RemoveAll(dir)
-		if err != nil {
-			t.Error(err)
-		}
-	}()
+	dir := t.TempDir()
 
 	absFile := filepath.Join(dir, file)
-	err = os.WriteFile(absFile, []byte(input), 0644)
+	err := os.WriteFile(absFile, []byte(input), 0o644)
 	if err != nil {
 		t.Error(err)
 	}
@@ -482,32 +474,31 @@ func runGoldenTest(t *testing.T, test Golden, opts generateOptions) {
 	g.generate(tokens[1], opts)
 
 	got := string(g.format())
-	expected, err := loadGolden(test.name)
-	if err != nil {
-		t.Fatalf("unexpected error while loading golden %q: %v", test.name, err)
-	}
-
-	if got != expected {
+	if expected := loadGolden(t, test.name); got != expected {
 		// Use this to help build a golden text when changes are needed
 		//goldenFile := fmt.Sprintf("./testdata/%v.golden", test.name)
-		//err = ioutil.WriteFile(goldenFile, []byte(got), 0644)
+		//err = os.WriteFile(goldenFile, []byte(got), 0644)
 		//if err != nil {
 		//	t.Error(err)
 		//}
 		t.Errorf("%s: got\n====\n%s====\nexpected\n====%s", test.name, got, expected)
 	}
 }
 
-func loadGolden(name string) (string, error) {
+func loadGolden(t *testing.T, name string) string {
+	t.Helper()
+
 	fh, err := os.Open("testdata/" + name + ".golden")
 	if err != nil {
-		return "", err
+		t.Fatalf("unable to open golden file for %s: %v", name, err)
 	}
+
 	defer fh.Close()
+
 	b, err := io.ReadAll(fh)
 	if err != nil {
-		return "", err
+		t.Fatalf("unable to read golden file for %s: %v", name, err)
 	}
-	return string(b), nil
 
+	return string(b)
 }

stringer.go

@@ -18,7 +18,6 @@ import (
 	"go/importer"
 	"go/token"
 	"go/types"
-	"io/ioutil"
 	"log"
 	"os"
 	"path/filepath"
@@ -178,7 +177,7 @@ func main() {
 	}
 
 	// Write to tmpfile first
-	tmpFile, err := ioutil.TempFile(dir, fmt.Sprintf("%s_enumer_", typs[0]))
+	tmpFile, err := os.CreateTemp(dir, fmt.Sprintf("%s_enumer_", typs[0]))
 	if err != nil {
 		log.Fatalf("creating temporary file for output: %s", err)
 	}
@@ -274,7 +273,7 @@ type Package struct {
 
 // parsePackage analyzes the single package constructed from the patterns and tags.
 // parsePackage exits if there is an error.
-func (g *Generator) parsePackage(patterns []string, tags []string) {
+func (g *Generator) parsePackage(patterns, tags []string) {
 	cfg := &packages.Config{
 		Mode: packages.LoadSyntax,
 		// TODO: Need to think about constants in test files. Maybe write type_string_test.go
@@ -734,11 +733,11 @@ func (g *Generator) declareIndexAndNameVar(run []Value, typeName string) {
 	g.Printf("var %s\n", index)
 	index, n = g.createLowerIndexAndNameDecl(run, typeName, "")
 	g.Printf("const %s\n", n)
-	//g.Printf("var %s\n", index)
+	// g.Printf("var %s\n", index)
 }
 
 // createIndexAndNameDecl returns the pair of declarations for the run. The caller will add "const" and "var".
-func (g *Generator) createLowerIndexAndNameDecl(run []Value, typeName string, suffix string) (string, string) {
+func (g *Generator) createLowerIndexAndNameDecl(run []Value, typeName, suffix string) (string, string) {
 	b := new(bytes.Buffer)
 	indexes := make([]int, len(run))
 	for i := range run {
@@ -760,7 +759,7 @@ func (g *Generator) createLowerIndexAndNameDecl(run []Value, typeName string, su
 }
 
 // createIndexAndNameDecl returns the pair of declarations for the run. The caller will add "const" and "var".
-func (g *Generator) createIndexAndNameDecl(run []Value, typeName string, suffix string) (string, string) {
+func (g *Generator) createIndexAndNameDecl(run []Value, typeName, suffix string) (string, string) {
 	b := new(bytes.Buffer)
 	indexes := make([]int, len(run))
 	for i := range run {
@@ -782,7 +781,7 @@ func (g *Generator) createIndexAndNameDecl(run []Value, typeName string, suffix
 }
 
 // declareNameVars declares the concatenated names string representing all the values in the runs.
-func (g *Generator) declareNameVars(runs [][]Value, typeName string, suffix string) {
+func (g *Generator) declareNameVars(runs [][]Value, typeName, suffix string) {
 	g.Printf("const _%sName%s = \"", typeName, suffix)
 	for _, run := range runs {
 		for i := range run {

util_test.go

@@ -12,8 +12,10 @@ import (
 )
 
 // Helpers to save typing in the test cases.
-type u []uint64
-type uu [][]uint64
+type (
+	u  []uint64
+	uu [][]uint64
+)
 
 type SplitTest struct {
 	input  u