fix: messages not getting handled when linking to a local module for development (#1814)

* fix: when doing local development and linking to a local module, the instanceof check results in skipped messages because TextMessage from different sources don't pass that check

* implement copilot review suggestions

Author: joeyguerra

src/Listener.mjs

@@ -1,7 +1,6 @@
 'use strict'
 
 import { inspect } from 'node:util'
-import { TextMessage } from './Message.mjs'
 import Middleware from './Middleware.mjs'
 
 class Listener {
@@ -97,7 +96,7 @@ class TextListener extends Listener {
   // callback - A Function that is triggered if the incoming message matches.
   constructor (robot, regex, options, callback) {
     function matcher (message) {
-      if (message instanceof TextMessage) {
+      if (typeof message.match === 'function') {
         return message.match(regex)
       }
     }

test/Listener_test.mjs

@@ -290,16 +290,32 @@ describe('Listener', () => {
         it('does not match EnterMessages', () => {
           const callback = async () => {}
           const testMessage = new EnterMessage(user)
-          testMessage.match = () => {
-            assert.fail('match should not be called')
-          }
           const testRegex = /test/
 
           const testListener = new TextListener(robot, testRegex, callback)
           const result = testListener.matcher(testMessage)
 
           assert.deepEqual(result, undefined)
         })
+
+        it('matches non-TextMessage objects with a match function (duck-typing regression test)', () => {
+          const callback = async () => {}
+          const testRegex = /test/
+          // Simulate a message from a linked module that isn't an instanceof TextMessage
+          const nonTextMessage = {
+            user: 'testuser',
+            text: 'test message',
+            match (regex) {
+              assert.deepEqual(regex, testRegex)
+              return true
+            }
+          }
+
+          const testListener = new TextListener(robot, testRegex, callback)
+          const result = testListener.matcher(nonTextMessage)
+
+          assert.ok(result)
+        })
       })
     )
   })