[MM-40144] Restructure tests, add test case numbers, some cleanup (#1864)

* [MM-40144] Restructure tests, add test case numbers, some cleanup

* Fix a test

e2e/specs/startup/app.test.js

@@ -0,0 +1,51 @@
+// Copyright (c) 2015-2016 Yuya Ochiai
+// Copyright (c) 2016-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+'use strict';
+
+const env = require('../../modules/environment');
+
+describe('startup/app', function desc() {
+    this.timeout(30000);
+
+    beforeEach(async () => {
+        env.createTestUserDataDir();
+        env.cleanTestConfig();
+        this.app = await env.getApp();
+    });
+
+    afterEach(async () => {
+        if (this.app) {
+            await this.app.close();
+        }
+    });
+
+    it('MM-T4399_1 should show the new server modal when no servers exist', async () => {
+        const newServerModal = this.app.windows().find((window) => window.url().includes('newServer'));
+        const modalTitle = await newServerModal.innerText('#newServerModal .modal-title');
+        modalTitle.should.equal('Add Server');
+    });
+
+    it('MM-T4399_2 should show no servers configured in dropdown when no servers exist', async () => {
+        const mainWindow = this.app.windows().find((window) => window.url().includes('index'));
+        const dropdownButtonText = await mainWindow.innerText('.TeamDropdownButton');
+        dropdownButtonText.should.equal('No servers configured');
+    });
+
+    it('MM-T4400 should be stopped when the app instance already exists', (done) => {
+        const secondApp = env.getApp();
+
+        // In the correct case, 'start().then' is not called.
+        // So need to use setTimeout in order to finish this test.
+        const timer = setTimeout(() => {
+            done();
+        }, 3000);
+        secondApp.then(() => {
+            clearTimeout(timer);
+            return secondApp.close();
+        }).then(() => {
+            done(new Error('Second app instance exists'));
+        });
+    });
+});