test(client): socket helper tests (#2095)

* test(client): socket helper tests

* test(client): rename socket test, rename mock variable

* test(client): renamed socket helper test filename

test/client/utils/__snapshots__/socket-helper.test.js.snap

@@ -0,0 +1,77 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`socket should default to SockJSClient when no __webpack_dev_server_client__ set 1`] = `
+Array [
+  "my.url",
+]
+`;
+
+exports[`socket should default to SockJSClient when no __webpack_dev_server_client__ set 2`] = `
+Array [
+  Array [
+    [Function],
+  ],
+]
+`;
+
+exports[`socket should default to SockJSClient when no __webpack_dev_server_client__ set 3`] = `
+Array [
+  Array [
+    [Function],
+  ],
+]
+`;
+
+exports[`socket should default to SockJSClient when no __webpack_dev_server_client__ set 4`] = `
+Array [
+  Array [
+    [Function],
+  ],
+]
+`;
+
+exports[`socket should default to SockJSClient when no __webpack_dev_server_client__ set 5`] = `
+Array [
+  Array [
+    "hello world",
+  ],
+]
+`;
+
+exports[`socket should use __webpack_dev_server_client__ when set 1`] = `
+Array [
+  "my.url",
+]
+`;
+
+exports[`socket should use __webpack_dev_server_client__ when set 2`] = `
+Array [
+  Array [
+    [Function],
+  ],
+]
+`;
+
+exports[`socket should use __webpack_dev_server_client__ when set 3`] = `
+Array [
+  Array [
+    [Function],
+  ],
+]
+`;
+
+exports[`socket should use __webpack_dev_server_client__ when set 4`] = `
+Array [
+  Array [
+    [Function],
+  ],
+]
+`;
+
+exports[`socket should use __webpack_dev_server_client__ when set 5`] = `
+Array [
+  Array [
+    "hello world",
+  ],
+]
+`;

test/client/utils/socket-helper.test.js

@@ -0,0 +1,71 @@
+'use strict';
+
+describe('socket', () => {
+  afterEach(() => {
+    jest.resetAllMocks();
+    jest.resetModules();
+  });
+
+  it('should default to SockJSClient when no __webpack_dev_server_client__ set', () => {
+    jest.mock('../../../client/clients/SockJSClient');
+    // eslint-disable-next-line global-require
+    const socket = require('../../../client/socket');
+    // eslint-disable-next-line global-require
+    const SockJSClient = require('../../../client/clients/SockJSClient');
+
+    const mockHandler = jest.fn();
+    socket('my.url', {
+      example: mockHandler,
+    });
+
+    const mockClientInstance = SockJSClient.mock.instances[0];
+
+    // this simulates recieving a message from the server and passing it
+    // along to the callback of onMessage
+    mockClientInstance.onMessage.mock.calls[0][0](
+      JSON.stringify({
+        type: 'example',
+        data: 'hello world',
+      })
+    );
+
+    expect(SockJSClient.mock.calls[0]).toMatchSnapshot();
+    expect(mockClientInstance.onOpen.mock.calls).toMatchSnapshot();
+    expect(mockClientInstance.onClose.mock.calls).toMatchSnapshot();
+    expect(mockClientInstance.onMessage.mock.calls).toMatchSnapshot();
+    expect(mockHandler.mock.calls).toMatchSnapshot();
+  });
+
+  it('should use __webpack_dev_server_client__ when set', () => {
+    jest.mock('../../../client/clients/SockJSClient');
+    // eslint-disable-next-line global-require
+    const socket = require('../../../client/socket');
+    // eslint-disable-next-line global-require
+    global.__webpack_dev_server_client__ = require('../../../client/clients/SockJSClient');
+
+    const mockHandler = jest.fn();
+    socket('my.url', {
+      example: mockHandler,
+    });
+
+    const mockClientInstance =
+      global.__webpack_dev_server_client__.mock.instances[0];
+
+    // this simulates recieving a message from the server and passing it
+    // along to the callback of onMessage
+    mockClientInstance.onMessage.mock.calls[0][0](
+      JSON.stringify({
+        type: 'example',
+        data: 'hello world',
+      })
+    );
+
+    expect(
+      global.__webpack_dev_server_client__.mock.calls[0]
+    ).toMatchSnapshot();
+    expect(mockClientInstance.onOpen.mock.calls).toMatchSnapshot();
+    expect(mockClientInstance.onClose.mock.calls).toMatchSnapshot();
+    expect(mockClientInstance.onMessage.mock.calls).toMatchSnapshot();
+    expect(mockHandler.mock.calls).toMatchSnapshot();
+  });
+});