feat: migrate fiber utils imports

cmd/internal/migrations/lists.go

@@ -47,6 +47,7 @@ var Migrations = []Migration{
 			v3migrations.MigrateCORSConfig,
 			v3migrations.MigrateCSRFConfig,
 			v3migrations.MigrateMonitorImport,
+			v3migrations.MigrateUtilsImport,
 			v3migrations.MigrateHealthcheckConfig,
 			v3migrations.MigrateProxyTLSConfig,
 			v3migrations.MigrateAppTestConfig,

cmd/internal/migrations/v3/common.go

@@ -521,6 +521,49 @@ func MigrateMonitorImport(cmd *cobra.Command, cwd string, _, _ *semver.Version)
 	return nil
 }
 
+// MigrateUtilsImport replaces old Fiber utils imports and updates removed helpers
+func MigrateUtilsImport(cmd *cobra.Command, cwd string, _, _ *semver.Version) error {
+	reImport := regexp.MustCompile(`(?m)^(\s*(?:\w+\s+)?)"github\.com/gofiber/fiber/v\d+/utils"$`)
+
+	err := internal.ChangeFileContent(cwd, func(content string) string {
+		// update import path
+		content = reImport.ReplaceAllString(content, `$1"github.com/gofiber/utils/v2"`)
+
+		// protect byte helper replacements so we can safely map string helpers to the
+		// standard library without affecting byte-based calls
+		content = strings.ReplaceAll(content, "utils.TrimRightBytes", "utils.__fiberTrimRight__")
+		content = strings.ReplaceAll(content, "utils.TrimLeftBytes", "utils.__fiberTrimLeft__")
+		content = strings.ReplaceAll(content, "utils.TrimBytes", "utils.__fiberTrim__")
+		content = strings.ReplaceAll(content, "utils.EqualFoldBytes", "utils.__fiberEqualFold__")
+
+		// map removed string helpers to the strings package
+		content = strings.ReplaceAll(content, "utils.TrimRight", "strings.TrimRight")
+		content = strings.ReplaceAll(content, "utils.TrimLeft", "strings.TrimLeft")
+		content = strings.ReplaceAll(content, "utils.Trim", "strings.Trim")
+		content = strings.ReplaceAll(content, "utils.EqualFold", "strings.EqualFold")
+
+		// restore byte helper placeholders to their new names
+		content = strings.ReplaceAll(content, "utils.__fiberTrimRight__", "utils.TrimRight")
+		content = strings.ReplaceAll(content, "utils.__fiberTrimLeft__", "utils.TrimLeft")
+		content = strings.ReplaceAll(content, "utils.__fiberTrim__", "utils.Trim")
+		content = strings.ReplaceAll(content, "utils.__fiberEqualFold__", "utils.EqualFold")
+
+		// other removed helpers
+		content = strings.ReplaceAll(content, "utils.GetString", "utils.ToString")
+		content = strings.ReplaceAll(content, "utils.GetBytes", "utils.CopyBytes")
+		content = strings.ReplaceAll(content, "utils.ImmutableString", "string")
+		content = strings.ReplaceAll(content, "utils.AssertEqual", "assert.Equal")
+
+		return content
+	})
+	if err != nil {
+		return fmt.Errorf("failed to migrate utils imports: %w", err)
+	}
+
+	cmd.Println("Migrating utils imports")
+	return nil
+}
+
 // MigrateProxyTLSConfig updates proxy TLS helper to new client configuration
 func MigrateProxyTLSConfig(cmd *cobra.Command, cwd string, _, _ *semver.Version) error {
 	re := regexp.MustCompile(`proxy\.WithTlsConfig\(([^)]+)\)`)

cmd/internal/migrations/v3/common_test.go

@@ -554,6 +554,57 @@ var _ = monitor.New()`)
 	assert.Contains(t, buf.String(), "Migrating monitor middleware import")
 }
 
+func Test_MigrateUtilsImport(t *testing.T) {
+	t.Parallel()
+
+	dir, err := os.MkdirTemp("", "mutils")
+	require.NoError(t, err)
+	defer func() { require.NoError(t, os.RemoveAll(dir)) }()
+
+	file := writeTempFile(t, dir, `package main
+import "github.com/gofiber/fiber/v3/utils"
+var (
+    _ = utils.TrimBytes([]byte("x"), " ")
+    _ = utils.TrimRightBytes([]byte("x"), " ")
+    _ = utils.TrimLeftBytes([]byte("x"), " ")
+    _ = utils.EqualFoldBytes([]byte("A"), []byte("a"))
+    _ = utils.Trim(" x ", " ")
+    _ = utils.TrimRight("x ", " ")
+    _ = utils.TrimLeft(" x", " ")
+    _ = utils.EqualFold("A", "a")
+    _ = utils.GetString([]byte("a"))
+    _ = utils.GetBytes("a")
+    _ = utils.ImmutableString([]byte("b"))
+)`)
+
+	var buf bytes.Buffer
+	cmd := newCmd(&buf)
+	require.NoError(t, v3.MigrateUtilsImport(cmd, dir, nil, nil))
+
+	content := readFile(t, file)
+	assert.Contains(t, content, "github.com/gofiber/utils/v2\"")
+	assert.NotContains(t, content, "fiber/v3/utils")
+	assert.NotContains(t, content, "TrimBytes(")
+	assert.NotContains(t, content, "TrimRightBytes(")
+	assert.NotContains(t, content, "TrimLeftBytes(")
+	assert.NotContains(t, content, "EqualFoldBytes(")
+	assert.NotContains(t, content, "GetString(")
+	assert.NotContains(t, content, "GetBytes(")
+	assert.NotContains(t, content, "ImmutableString(")
+	assert.Contains(t, content, "utils.Trim(")
+	assert.Contains(t, content, "utils.TrimRight(")
+	assert.Contains(t, content, "utils.TrimLeft(")
+	assert.Contains(t, content, "utils.EqualFold(")
+	assert.Contains(t, content, "strings.Trim(")
+	assert.Contains(t, content, "strings.TrimRight(")
+	assert.Contains(t, content, "strings.TrimLeft(")
+	assert.Contains(t, content, "strings.EqualFold(")
+	assert.Contains(t, content, "utils.ToString(")
+	assert.Contains(t, content, "utils.CopyBytes(")
+	assert.Contains(t, content, "string([]byte(\"b\"))")
+	assert.Contains(t, buf.String(), "Migrating utils imports")
+}
+
 func Test_MigrateProxyTLSConfig(t *testing.T) {
 	t.Parallel()