1 files changed, 41 insertions, 0 deletions
diff --git a/src/cmd/go/help_test.go b/src/cmd/go/help_test.go
new file mode 100644
index 0000000..3e1d817
--- /dev/null
+++ b/src/cmd/go/help_test.go
@@ -0,0 +1,41 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main_test
+
+import (
+	"bytes"
+	"go/format"
+	diffpkg "internal/diff"
+	"os"
+	"testing"
+
+	"cmd/go/internal/help"
+	"cmd/go/internal/modload"
+)
+
+func TestDocsUpToDate(t *testing.T) {
+	t.Parallel()
+
+	if !modload.Enabled() {
+		t.Skipf("help.Help in GOPATH mode is configured by main.main")
+	}
+
+	buf := new(bytes.Buffer)
+	// Match the command in mkalldocs.sh that generates alldocs.go.
+	help.Help(buf, []string{"documentation"})
+	internal := buf.Bytes()
+	internal, err := format.Source(internal)
+	if err != nil {
+		t.Fatalf("gofmt docs: %v", err)
+	}
+	alldocs, err := os.ReadFile("alldocs.go")
+	if err != nil {
+		t.Fatalf("error reading alldocs.go: %v", err)
+	}
+	if !bytes.Equal(internal, alldocs) {
+		t.Errorf("alldocs.go is not up to date; run mkalldocs.sh to regenerate it\n%s",
+			diffpkg.Diff("go help documentation | gofmt", internal, "alldocs.go", alldocs))
+	}
+}