Add flag --skip-generated to skip generated code (#150)

This diff adds the flag `--skip-generated` to be able to skip running
gopatch on files containing generated code. When the flag is set to
true, if the comments contains `@generated` or the special go generated
code comment `^// Code generated .* DO NOT EDIT\.$`, we do not run
gopatch on that particular file.
We are adding a check for the former case(@generated) as at times, the
generated code does not follow the the special go generated code format
perfectly.

Example:
For test file
`testdata/test_file/skip_generated_file/special_notation_generated.go`,
if we apply the patch `testdata/patch/time.go`

Without running `--skip-generated`, the file gets modified to
```
--- testdata/test_files/skip_generated_files/test1.go
+++ testdata/test_files/skip_generated_files/test1.go
@@ -9,6 +9,6 @@

 func main() {
        startOfYear := time.Date(2021, 0o1, 0o1, 0, 0, 0, 0, time.UTC)
-       result := time.Now().Sub(startOfYear)
+       result := time.Since(startOfYear)
        fmt.Println(result)
 }
```
Running with flag `--skip-generated`, file isn't modified at all.
Internal ref: GO-2502

Note: We also upgraded the go version to 1.22 to use the
[ast.IsGenerated ](https://pkg.go.dev/go/ast#IsGenerated) function which
was introduced in 1.21.

.github/workflows/go.yml

@@ -16,7 +16,7 @@ jobs:
     - name: Set up Go
       uses: actions/setup-go@v5
       with:
-        go-version: 1.20.x
+        go-version: 1.22.x
 
     - name: Load cached dependencies
       uses: actions/cache@v4

.github/workflows/release.yml

@@ -15,7 +15,7 @@ jobs:
     - name: Setup Go
       uses: actions/setup-go@v5
       with:
-        go-version: 1.20.x
+        go-version: 1.22.x
 
     - name: Checkout
       uses: actions/checkout@v4

e2e_test.go

@@ -169,6 +169,43 @@ func runIntegrationTest(t *testing.T, testFile string) {
 	}
 }
 
+func TestGeneratedE2e(t *testing.T) {
+	patch := "testdata/patch/time.patch"
+	t.Parallel()
+	tests := []struct {
+		name string
+		path string
+		want string
+	}{
+		{
+			name: "go special comment for generated code",
+			path: "testdata/test_files/skip_generated_files/special_notation_generated.go",
+		},
+		{
+			name: "@generated",
+			path: "testdata/test_files/skip_generated_files/simple_generated.go",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			want, err := os.ReadFile(tt.path)
+			require.NoError(t, err)
+			var stdoutbuf bytes.Buffer
+			cmd := mainCmd{
+				Stdout: &stdoutbuf,
+				Getwd:  os.Getwd,
+			}
+			err = cmd.Run([]string{"--skip-generated", "-p", patch, tt.path})
+			require.NoError(t, err, "could not run patch")
+			assert.Empty(t, stdoutbuf)
+			// verify the target file's content didn't modify.
+			got, err := os.ReadFile(tt.path)
+			require.NoError(t, err)
+			assert.Equal(t, want, got)
+		})
+	}
+}
+
 // includeSkipImportTest returns whether we should include a testfile for
 // the skipImportProcessing flag testing
 func includeSkipImportTest(testFile, testName string) bool {

go.mod

@@ -1,6 +1,6 @@
 module github.com/uber-go/gopatch
 
-go 1.18
+go 1.22
 
 require (
 	github.com/google/go-intervals v0.0.2

main.go

@@ -58,6 +58,7 @@ type options struct {
 	DisplayVersion       bool      `long:"version"`
 	Print                bool      `long:"print-only"`
 	SkipImportProcessing bool      `long:"skip-import-processing"`
+	SkipGenerated        bool      `long:"skip-generated"`
 	Args                 arguments `positional-args:"yes"`
 	Verbose              bool      `short:"v" long:"verbose"`
 }
@@ -94,6 +95,10 @@ func newArgParser() (*flags.Parser, *options) {
 
 	parser.FindOptionByLongName("skip-import-processing").
 		Description = "Skips processing of imports."
+
+	parser.FindOptionByLongName("skip-generated").
+		Description = "Skips running on files with generated code."
+
 	parser.Args()[0].
 		Description = "One or more files or directores containing Go code. " +
 		"When directories are provided, all Go files in them and their " +
@@ -284,6 +289,11 @@ func (cmd *mainCmd) Run(args []string) error {
 			continue
 		}
 
+		if opts.SkipGenerated && checkGeneratedCode(f) {
+			log.Printf("generated file %s: skipped", filename)
+			continue
+		}
+
 		f, comments, ok := patchRunner.Apply(filename, f)
 		// If at least one patch didn't match, there's nothing to do.
 		// If --print-only was passed, print the contents out as-is.
@@ -341,6 +351,18 @@ func (cmd *mainCmd) Run(args []string) error {
 	return multierr.Combine(errors...)
 }
 
+func checkGeneratedCode(f *ast.File) bool {
+	if ast.IsGenerated(f) {
+		return true
+	}
+	for _, comm := range f.Doc.List {
+		if strings.Contains(comm.Text, "@generated") {
+			return true
+		}
+	}
+	return false
+}
+
 func (cmd *mainCmd) preview(
 	filename string,
 	originalContent, modifiedContent []byte,

main_test.go

@@ -24,6 +24,7 @@ package main
 
 import (
 	"bytes"
+	"go/ast"
 	"go/token"
 	"os"
 	"path/filepath"
@@ -60,6 +61,15 @@ func TestNewArgParser(t *testing.T) {
 					SkipImportProcessing: false,
 				},
 			},
+			{
+				desc: "skip-generated",
+				give: []string{"--skip-generated", "-p", "testdata/patch/replace_to_with_ptr.patch", "testdata/test_files/skip_generated_files/test1.go"},
+				want: options{
+					Patches:       []string{"testdata/patch/replace_to_with_ptr.patch"},
+					Args:          arguments{Patterns: []string{"testdata/test_files/skip_generated_files/test1.go"}},
+					SkipGenerated: true,
+				},
+			},
 			{
 				desc: "skip-import-processing",
 				give: []string{"--skip-import-processing", "-p", "testdata/patch/replace_to_with_ptr.patch", "testdata/test_files/skip_import_processing_example/test1.go"},
@@ -78,6 +88,7 @@ func TestNewArgParser(t *testing.T) {
 				assert.Equal(t, tt.want.Patches, opts.Patches)
 				assert.Equal(t, tt.want.Args, opts.Args)
 				assert.Equal(t, tt.want.Diff, opts.Diff)
+				assert.Equal(t, tt.want.SkipGenerated, opts.SkipGenerated)
 				assert.Equal(t, tt.want.SkipImportProcessing, opts.SkipImportProcessing)
 			})
 		}
@@ -211,3 +222,41 @@ func TestPreview(t *testing.T) {
 			stdout.String())
 	})
 }
+
+func TestCheckGeneratedCode(t *testing.T) {
+	t.Parallel()
+	tests := []struct {
+		name string
+		file *ast.File
+		want bool
+	}{
+		{
+			name: "@generated",
+			file: &ast.File{
+				Doc: &ast.CommentGroup{
+					List: []*ast.Comment{
+						{Text: "@generated"},
+					},
+				},
+			},
+			want: true,
+		},
+		{
+			name: "non-generated code",
+			file: &ast.File{
+				Doc: &ast.CommentGroup{
+					List: []*ast.Comment{
+						{Text: "sad times"},
+						{Text: "not generated code"},
+					},
+				},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := checkGeneratedCode(tt.file)
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}

tools/go.mod

@@ -1,6 +1,6 @@
 module github.com/uber-go/gopatch/tools
 
-go 1.18
+go 1.22
 
 require (
 	github.com/stretchr/testify v1.8.4

tools/go.sum

@@ -19,6 +19,7 @@ golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.3.0 h1:ftCYgMx6zT/asHUrPw8BLLscYtGznsLAnjq5RH9P66E=
+golang.org/x/sync v0.3.0/go.mod h1:FU7BRWz2tNW+3quACPkgCx/L+uEAv1htQ0V83Z9Rj+Y=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.11.0 h1:eG7RXZHdqOJ1i+0lgLgCpSXAp6M3LYlAo6osgSi0xOM=