feat: error out when a path matches multiple formatters

Signed-off-by: Brian McGee <[email protected]>

cli/format.go

@@ -372,20 +372,24 @@ func applyFormatters(ctx context.Context) func() error {
 
 		// iterate the files channel, checking if any pipeline wants it, and attempting to apply if so.
 		for file := range filesCh {
-			var matched bool
+			var matches []string
+
 			for key, pipeline := range pipelines {
 				if !pipeline.Wants(file) {
 					continue
 				}
-				matched = true
+				matches = append(matches, key)
 				tryApply(key, file)
 			}
-			if matched {
-				stats.Add(stats.Matched, 1)
-			} else {
+			switch len(matches) {
+			case 0:
 				log.Debugf("no match found: %s", file.Path)
 				// no match, so we send it direct to the processed channel
 				processedCh <- file
+			case 1:
+				stats.Add(stats.Matched, 1)
+			default:
+				return fmt.Errorf("path '%s' matched multiple formatters/pipelines %v", file.Path, matches)
 			}
 		}
 

cli/format_test.go

@@ -196,6 +196,37 @@ func TestIncludesAndExcludes(t *testing.T) {
 	assertStats(t, as, 31, 31, 2, 0)
 }
 
+func TestMatchingMultiplePipelines(t *testing.T) {
+	as := require.New(t)
+
+	tempDir := test.TempExamples(t)
+	configPath := tempDir + "/multiple.toml"
+
+	cfg := config2.Config{
+		Formatters: map[string]*config2.Formatter{
+			"echo": {
+				Command:  "echo",
+				Includes: []string{"*"},
+			},
+			"touch": {
+				Command:  "touch",
+				Includes: []string{"*"},
+			},
+		},
+	}
+
+	test.WriteConfig(t, configPath, cfg)
+	_, err := cmd(t, "-c", "--config-file", configPath, "--tree-root", tempDir)
+	as.ErrorContains(err, "matched multiple formatters/pipelines")
+	as.ErrorContains(err, "echo")
+	as.ErrorContains(err, "touch")
+
+	// run with only one formatter
+	test.WriteConfig(t, configPath, cfg)
+	_, err = cmd(t, "-c", "--config-file", configPath, "--tree-root", tempDir, "-f", "echo")
+	as.NoError(err)
+}
+
 func TestCache(t *testing.T) {
 	as := require.New(t)