fix: support send without to argument

lib/core/messenger/local.js

@@ -88,29 +88,31 @@ class Messenger extends EventEmitter {
    * @return {Messenger} this
    */
   send(action, data, to) {
-    const { egg } = this;
-    let application;
-    let agent;
-    let opposite;
-    if (egg.type === 'application') {
-      application = egg;
-      agent = egg.agent;
-      opposite = agent;
-    } else {
-      agent = egg;
-      application = egg.application;
-      opposite = application;
-    }
-
     // use nextTick to keep it async as IPC messenger
     process.nextTick(() => {
-      if (application.messenger && (to === 'application' || to === 'both')) {
+      const { egg } = this;
+      let application;
+      let agent;
+      let opposite;
+
+      if (egg.type === 'application') {
+        application = egg;
+        agent = egg.agent;
+        opposite = agent;
+      } else {
+        agent = egg;
+        application = egg.application;
+        opposite = application;
+      }
+      if (!to) to = egg.type === 'application' ? 'agent' : 'application';
+
+      if (application && application.messenger && (to === 'application' || to === 'both')) {
         application.messenger._onMessage({ action, data });
       }
-      if (agent.messenger && (to === 'agent' || to === 'both')) {
+      if (agent && agent.messenger && (to === 'agent' || to === 'both')) {
         agent.messenger._onMessage({ action, data });
       }
-      if (opposite.messenger && to === 'opposite') {
+      if (opposite && opposite.messenger && to === 'opposite') {
         opposite.messenger._onMessage({ action, data });
       }
     });

test/lib/core/messenger/local.test.js

@@ -3,6 +3,7 @@
 const utils = require('../../../utils');
 const pedding = require('pedding');
 const assert = require('assert');
+const mm = require('egg-mock');
 
 describe('test/lib/core/messenger/local.test.js', () => {
   let app;
@@ -14,6 +15,7 @@ describe('test/lib/core/messenger/local.test.js', () => {
   after(() => app.close());
 
   afterEach(() => {
+    mm.restore();
     app.messenger.close();
     app.agent.messenger.close();
   });
@@ -161,4 +163,37 @@ describe('test/lib/core/messenger/local.test.js', () => {
       app.agent.messenger.sendTo(process.pid, 'sendTo-event', { foo: 'bar' });
     });
   });
+
+  describe('send()', () => {
+    it('app.messenger.send should not throw when app.agent not exist', () => {
+      mm(app, 'agent', undefined);
+      app.messenger.send('send-event', { foo: 'bar' });
+    });
+
+    it('app.messenger.send should work', done => {
+      app.agent.messenger.once('send-event', msg => {
+        assert.deepEqual(msg, { foo: 'bar' });
+        done();
+      });
+
+      app.messenger.once('send-event', () => {
+        throw new Error('should not emit on app');
+      });
+
+      app.messenger.send('send-event', { foo: 'bar' });
+    });
+
+    it('agent.messenger.send should work', done => {
+      app.agent.messenger.once('send-event', () => {
+        throw new Error('should not emit on agent');
+      });
+
+      app.messenger.once('send-event', msg => {
+        assert.deepEqual(msg, { foo: 'bar' });
+        done();
+      });
+
+      app.agent.messenger.send('send-event', { foo: 'bar' });
+    });
+  });
 });