Write gen DIR's manifest to DIR/index.mf (closes #178)

Without --output, gen given one directory now writes index.mf in it, and given one file writes index.mf beside it; with no path or several, it still writes index.mf in the current directory. What gen lists depends only on its arguments and the tree, never on where the manifest is written, so gen DIR followed by check DIR passes. Scanner.EnumeratePaths lists a file argument by its name, as EnumerateFile does. Before, it listed the file under an empty path and gen stopped with "path cannot be empty". The --output help text and the README's Tool Examples state the default. Model: opus-5-5
2026-10-07 21:09:06 +00:00
parent e35cd4a045
commit 23df19763f
6 changed files with 200 additions and 10 deletions
@@ -1289,6 +1289,127 @@ func TestGenerateLeavesLeftoverTempFileOutOfListing(t *testing.T) {
 	assert.Equal(t, []string{testFileTxt}, manifestPaths(t, fs, output))
 }

+// writeTestTree writes file.txt and sub/nested.txt under dir.
+func writeTestTree(t *testing.T, fs afero.Fs, dir string) {
+	t.Helper()
+
+	require.NoError(t, fs.MkdirAll(filepath.Join(dir, testSubdir), 0o750))
+	writeTestFile(t, fs, filepath.Join(dir, testFileTxt), "hello")
+	writeTestFile(t, fs, filepath.Join(dir, testSubdir, "nested.txt"), "in sub")
+}
+
+// TestGenerateDefaultOutput runs gen without --output on one directory or
+// one file: it writes index.mf in that directory, or beside that file,
+// listing each file by its path under the directory index.mf is in, and
+// check given that directory passes.
+func TestGenerateDefaultOutput(t *testing.T) {
+	t.Parallel()
+
+	// Paths are relative to a temp dir holding file.txt and sub/nested.txt.
+	for name, tc := range map[string]struct {
+		input, output string
+		listed        []string
+	}{
+		"directory": {
+			".", defaultManifestName, []string{testFileTxt, "sub/nested.txt"},
+		},
+		"subdirectory": {testSubdir, testSubdirManifest, []string{"nested.txt"}},
+		"file":         {testFileTxt, defaultManifestName, []string{testFileTxt}},
+	} {
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			root := t.TempDir()
+			fs := afero.NewOsFs()
+			writeTestTree(t, fs, root)
+
+			opts := testOpts([]string{
+				testApp, cmdGenerate, "-q", filepath.Join(root, tc.input),
+			}, fs)
+			require.Equal(t, 0, runCLI(opts), "stderr: %s", testStderr(t, opts))
+
+			output := filepath.Join(root, tc.output)
+			assert.ElementsMatch(t, tc.listed, manifestPaths(t, fs, output))
+
+			opts = testOpts([]string{
+				testApp, cmdCheck, "-q", filepath.Dir(output),
+			}, fs)
+			assert.Equal(t, 0, runCLI(opts), "stderr: %s", testStderr(t, opts))
+		})
+	}
+}
+
+// TestGenerateBytesDoNotDependOnOutput runs gen --seed on one tree, each
+// time writing to another file, over a file already there and beside an
+// earlier run's temp file: neither is listed, and what is listed depends
+// only on the tree, so every manifest has the same bytes.
+func TestGenerateBytesDoNotDependOnOutput(t *testing.T) {
+	t.Parallel()
+
+	root := t.TempDir()
+	tree := filepath.Join(root, "tree")
+	defaultOutput := filepath.Join(tree, defaultManifestName)
+
+	fs := afero.NewOsFs()
+	writeTestTree(t, fs, tree)
+
+	var first []byte
+
+	for _, output := range []string{
+		defaultOutput,
+		filepath.Join(tree, "listing.mf"),
+		filepath.Join(tree, testSubdir, "listing.mf"),
+		filepath.Join(root, "outside.mf"),
+	} {
+		writeTestFile(t, fs, output, "previous manifest")
+		writeTestFile(t, fs, manifestTempPath(output), "part of a manifest")
+
+		args := []string{testApp, cmdGenerate, "-q", "-f", "--seed", "mfer"}
+		if output != defaultOutput {
+			args = append(args, "-o", output)
+		}
+
+		args = append(args, tree)
+
+		opts := testOpts(args, fs)
+		require.Equal(t, 0, runCLI(opts),
+			"output %s, stderr: %s", output, testStderr(t, opts))
+
+		got, err := afero.ReadFile(fs, output)
+		require.NoError(t, err)
+		require.NoError(t, fs.Remove(output))
+
+		if first == nil {
+			first = got
+		}
+
+		assert.Equal(t, first, got, "output %s", output)
+	}
+}
+
+// TestGenerateRefusesExistingDefaultOutput runs gen without --output or
+// --force on a directory already holding index.mf: gen fails, naming that
+// file, and leaves it as it was.
+func TestGenerateRefusesExistingDefaultOutput(t *testing.T) {
+	t.Parallel()
+
+	output := filepath.Join(testDir, defaultManifestName)
+
+	fs := afero.NewMemMapFs()
+	require.NoError(t, fs.MkdirAll(testDir, 0o755))
+	writeTestFile(t, fs, testFile1, "hello")
+	writeTestFile(t, fs, output, "previous manifest")
+
+	opts := testOpts([]string{testApp, cmdGenerate, "-q", testDir}, fs)
+	assert.Equal(t, 1, runCLI(opts))
+	assert.Contains(t, testStderr(t, opts),
+		"output file "+output+" already exists (use --force to overwrite)")
+
+	content, err := afero.ReadFile(fs, output)
+	require.NoError(t, err)
+	assert.Equal(t, "previous manifest", string(content))
+}
+
 func TestGenerateAtomicWriteUsesTemp(t *testing.T) {
 	t.Parallel()

@@ -88,9 +88,34 @@ func (mfa *CLIApp) collectInputPaths(args cli.Args) ([]string, error) {
 	return paths, nil
 }

-// buildScannerOptions constructs scanner options from the CLI flags.
-func (mfa *CLIApp) buildScannerOptions(cmd *cli.Command) *mfer.ScannerOptions {
-	output := cmd.String("output")
+// outputPath returns the file gen writes the manifest to: the one --output
+// names, or else index.mf in the directory the only argument names, or
+// beside the file it names, or else in the current directory.
+func (mfa *CLIApp) outputPath(cmd *cli.Command) string {
+	if output := cmd.String("output"); output != "" {
+		return output
+	}
+
+	if cmd.Args().Len() != 1 {
+		return defaultManifestName
+	}
+
+	arg := cmd.Args().First()
+
+	// A path that does not exist is refused when it is enumerated.
+	info, err := mfa.Fs.Stat(arg)
+	if err == nil && !info.IsDir() {
+		return filepath.Join(filepath.Dir(arg), defaultManifestName)
+	}
+
+	return filepath.Join(arg, defaultManifestName)
+}
+
+// buildScannerOptions constructs scanner options from the CLI flags and
+// the path the manifest is written to.
+func (mfa *CLIApp) buildScannerOptions(
+	cmd *cli.Command, output string,
+) *mfer.ScannerOptions {
 	opts := &mfer.ScannerOptions{
 		IncludeDotfiles:    cmd.Bool("include-dotfiles"),
 		FollowSymLinks:     cmd.Bool("follow-symlinks"),
@@ -207,7 +232,8 @@ func (mfa *CLIApp) generateManifestOperation(
 ) error {
 	log.Debug("generateManifestOperation()")

-	s := mfer.NewScannerWithOptions(mfa.buildScannerOptions(cmd))
+	outputPath := mfa.outputPath(cmd)
+	s := mfer.NewScannerWithOptions(mfa.buildScannerOptions(cmd, outputPath))

 	// Phase 1: Enumeration - collect paths and stat files
 	err := mfa.runEnumeratePhase(cmd, s)
@@ -218,7 +244,6 @@ func (mfa *CLIApp) generateManifestOperation(
 	showProgress := cmd.Bool("progress")

 	// Check if output file exists
-	outputPath := cmd.String("output")
 	if exists, _ := afero.Exists(mfa.Fs, outputPath); exists && !cmd.Bool("force") {
 		return fmt.Errorf("output file %s %w", outputPath, errOutputExists)
 	}
@@ -211,9 +211,10 @@ func (mfa *CLIApp) generateCommand() *cli.Command {
 			},
 			&cli.StringFlag{
 				Name:    "output",
-				Value:   defaultManifestName,
 				Aliases: []string{"o"},
-				Usage:   "Specify output filename",
+				Usage: "File to write the manifest to (default: index.mf in " +
+					"the directory given, or beside the file given; with no " +
+					"path or several, index.mf in the current directory)",
 			},
 			&cli.BoolFlag{
 				Name:    "force",