Add support for established chat user mode. #1587 (#1681)

* Add support for established user mode. #1587

* Tweak tests

* Tweak tests

* Update test

* Fix test.

test/automated/api/chat.test.js

@@ -27,10 +27,12 @@ test('can fetch chat messages', async (done) => {
     .auth('admin', 'abc123')
     .expect(200);
 
-  const expectedBody = `${testMessage.body}`;
-  const message = res.body.filter(function (msg) {
-    return msg.body === expectedBody;
-  })[0];
+  const message = res.body.filter((m) => m.body === testMessage.body)[0];
+  if (!message) {
+    throw new Error('Message not found');
+  }
+
+  const expectedBody = testMessage.body;
 
   expect(message.body).toBe(expectedBody);
   expect(message.user.displayName).toBe(userDisplayName);
@@ -52,7 +54,7 @@ test('can derive display name from user header', async (done) => {
 test('can overwrite user header derived display name with body', async (done) => {
   const res = await request
     .post('/api/chat/register')
-    .send({displayName: 'TestUserChat'})
+    .send({ displayName: 'TestUserChat' })
     .set('X-Forwarded-User', 'test-user')
     .expect(200);