[release-branch.go1.27] Skip doc reproducibility test if document is a copy

eng/_util/cmd/updatecryptodocs/updatecryptodocs_test.go

@@ -9,6 +9,8 @@ import (
 	"path/filepath"
 	"strings"
 	"testing"
+
+	"github.com/microsoft/go/_util/internal/docutil"
 )
 
 func TestUpdateCryptoDocsReproducible(t *testing.T) {
@@ -17,6 +19,7 @@ func TestUpdateCryptoDocsReproducible(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Failed to read checked-in document at %q: %v", checkedInPath, err)
 	}
+	skipIfCopiedDocument(t, checkedIn)
 
 	generated, err := generate()
 	if err != nil {
@@ -37,6 +40,7 @@ func TestUpdateUserGuideReproducible(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Failed to read checked-in document at %q: %v", checkedInPath, err)
 	}
+	skipIfCopiedDocument(t, checkedIn)
 
 	generated, err := generateUserGuide()
 	if err != nil {
@@ -50,3 +54,10 @@ func TestUpdateUserGuideReproducible(t *testing.T) {
 		t.Errorf("Generated document does not match checked-in document. Run this command to update:\n  pwsh eng/run.ps1 updatecryptodocs")
 	}
 }
+
+func skipIfCopiedDocument(t *testing.T, contents []byte) {
+	t.Helper()
+	if docutil.IsCopied(contents) {
+		t.Skip("Document is maintained by automatic copying, not local regeneration.")
+	}
+}

eng/_util/internal/docutil/docutil.go

@@ -0,0 +1,13 @@
+// Copyright (c) Microsoft Corporation.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package docutil
+
+import "strings"
+
+// IsCopied reports whether contents start with the automatic documentation copy notice.
+func IsCopied(contents []byte) bool {
+	normalized := strings.ReplaceAll(string(contents), "\r\n", "\n")
+	return strings.HasPrefix(normalized, "<!--\nDO NOT EDIT THIS COPY.\nLocal edits will be overwritten.")
+}

eng/_util/internal/docutil/docutil_test.go

@@ -0,0 +1,34 @@
+// Copyright (c) Microsoft Corporation.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package docutil
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestIsCopied(t *testing.T) {
+	const prefix = "<!--\nDO NOT EDIT THIS COPY.\nLocal edits will be overwritten."
+	for _, tt := range []struct {
+		name     string
+		contents string
+		want     bool
+	}{
+		{"copy", prefix + "\n-->\nCopied document.\n", true},
+		{"copy_crlf", strings.ReplaceAll(prefix+"\n-->\nCopied document.\n", "\n", "\r\n"), true},
+		{"prefix_only", prefix, true},
+		{"empty", "", false},
+		{"local", "Generated document.\n", false},
+		{"partial_prefix", "<!--\nDO NOT EDIT THIS COPY.\n", false},
+		{"prefix_in_body", "Generated document.\n" + prefix, false},
+		{"leading_newline", "\n" + prefix, false},
+	} {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := IsCopied([]byte(tt.contents)); got != tt.want {
+				t.Errorf("IsCopied() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}