feat: support src/command/index cmd (#141)

src/main.ts

@@ -4,6 +4,8 @@ import {HelpBase} from '@oclif/plugin-help'
 import {Command} from '.'
 import {getHelpClass} from '@oclif/plugin-help'
 
+const ROOT_INDEX_CMD_ID = ''
+
 export class Main extends Command {
   static run(argv = process.argv.slice(2), options?: Config.LoadOptions) {
     return super.run(argv, options || (module.parent && module.parent.parent && module.parent.parent.filename) || __dirname)
@@ -16,19 +18,23 @@ export class Main extends Command {
   }
 
   async run() {
-    const [id, ...argv] = this.argv
+    let [id, ...argv] = this.argv
     this.parse({strict: false, '--': false, ...this.ctor as any})
     if (!this.config.findCommand(id)) {
       const topic = this.config.findTopic(id)
       if (topic) return this._help()
+      if (this.config.findCommand(ROOT_INDEX_CMD_ID)) {
+        id = ROOT_INDEX_CMD_ID
+        argv = this.argv
+      }
     }
     await this.config.runCommand(id, argv)
   }
 
   protected _helpOverride(): boolean {
     if (['-v', '--version', 'version'].includes(this.argv[0])) return this._version() as any
     if (['-h', 'help'].includes(this.argv[0])) return true
-    if (this.argv.length === 0) return true
+    if (this.argv.length === 0 && !this.config.findCommand(ROOT_INDEX_CMD_ID)) return true
     for (const arg of this.argv) {
       if (arg === '--help') return true
       if (arg === '--') return false