List formatters in help command

src/formatter/builder.ts

@@ -61,30 +61,21 @@ const FormatterBuilder = {
   },
 
   getConstructorByType(type: string, cwd: string): typeof Formatter {
-    switch (type) {
-      case 'json':
-        return JsonFormatter
-      case 'message':
-        return MessageFormatter
-      case 'html':
-        return HtmlFormatter
-      case 'progress':
-        return ProgressFormatter
-      case 'progress-bar':
-        return ProgressBarFormatter
-      case 'rerun':
-        return RerunFormatter
-      case 'snippets':
-        return SnippetsFormatter
-      case 'summary':
-        return SummaryFormatter
-      case 'usage':
-        return UsageFormatter
-      case 'usage-json':
-        return UsageJsonFormatter
-      default:
-        return FormatterBuilder.loadCustomFormatter(type, cwd)
+    const formatters: Record<string, typeof Formatter> = {
+      json: JsonFormatter,
+      message: MessageFormatter,
+      html: HtmlFormatter,
+      progress: ProgressFormatter,
+      'progress-bar': ProgressBarFormatter,
+      rerun: RerunFormatter,
+      snippets: SnippetsFormatter,
+      summary: SummaryFormatter,
+      usage: UsageFormatter,
+      'usage-json': UsageJsonFormatter,
+      default: FormatterBuilder.loadCustomFormatter(type, cwd),
     }
+
+    return formatters[type] ? formatters[type] : formatters.default
   },
 
   getStepDefinitionSnippetBuilder({

src/formatter/index.ts

@@ -39,6 +39,7 @@ export default class Formatter {
   protected stream: WritableStream
   protected supportCodeLibrary: ISupportCodeLibrary
   private readonly cleanup: IFormatterCleanupFn
+  protected readonly documentation: string
 
   constructor(options: IFormatterOptions) {
     this.colorFns = options.colorFns