test: add pop-up notification test

packages/e2e-tests/fixtures/apps/mattermost/add-mattermost-connection-modal.js

@@ -0,0 +1,25 @@
+const { BasePage } = require('../../base-page');
+
+export class AddMattermostConnectionModal extends BasePage {
+
+  /**
+   * @param {import('@playwright/test').Page} page
+   */
+  constructor (page) {
+    super(page);
+    this.clientIdInput = page.getByTestId('clientId-text');
+    this.clientIdSecretInput = page.getByTestId('clientSecret-text');
+    this.instanceUrlInput = page.getByTestId("instanceUrl-text");
+    this.submitButton = page.getByTestId('create-connection-button');
+  }
+
+  async fillConnectionForm() {
+    await this.instanceUrlInput.fill('https://mattermost.com');
+    await this.clientIdInput.fill('aaa');
+    await this.clientIdSecretInput.fill('bbb');
+  }
+
+  async submitConnectionForm() {
+    await this.submitButton.click();
+  }
+}