feat(backend-git-gateway): handle identity disabled error message (#3002)

packages/netlify-cms-backend-git-gateway/src/__tests__/AuthenticationPage.spec.js

@@ -0,0 +1,42 @@
+import React from 'react';
+import { Map } from 'immutable';
+import { render } from '@testing-library/react';
+
+window.netlifyIdentity = {
+  currentUser: jest.fn(),
+  on: jest.fn(),
+  close: jest.fn(),
+};
+
+describe('GitGatewayAuthenticationPage', () => {
+  const props = {
+    config: Map({ logo_url: 'logo_url' }),
+    t: jest.fn(key => key),
+    onLogin: jest.fn(),
+    inProgress: false,
+  };
+
+  beforeEach(() => {
+    jest.clearAllMocks();
+    jest.resetModules();
+  });
+
+  it('should render with identity error', () => {
+    const { default: GitGatewayAuthenticationPage } = require('../AuthenticationPage');
+    const { asFragment } = render(<GitGatewayAuthenticationPage {...props} />);
+
+    const errorCallback = window.netlifyIdentity.on.mock.calls.find(call => call[0] === 'error')[1];
+
+    errorCallback(
+      new Error('Failed to load settings from https://site.netlify.com/.netlify/identity'),
+    );
+
+    expect(asFragment()).toMatchSnapshot();
+  });
+
+  it('should render with no identity error', () => {
+    const { default: GitGatewayAuthenticationPage } = require('../AuthenticationPage');
+    const { asFragment } = render(<GitGatewayAuthenticationPage {...props} />);
+    expect(asFragment()).toMatchSnapshot();
+  });
+});