api.js refactor using classes (#250)

Refactor api.js into an api module where endpoint specific models can be imported and used in components.

__tests__/api/root.test.jsx

@@ -0,0 +1,45 @@
+import Root from '../../src/api/models/Root';
+
+describe('RootAPI', () => {
+  const createPromise = () => Promise.resolve();
+  const mockHttp = ({ get: jest.fn(createPromise), post: jest.fn(createPromise) });
+
+  const RootAPI = new Root(mockHttp);
+
+  afterEach(() => {
+    jest.clearAllMocks();
+  });
+
+  test('login calls get and post with expected content headers', async (done) => {
+    const headers = { 'Content-Type': 'application/x-www-form-urlencoded' };
+
+    await RootAPI.login('username', 'password');
+
+    expect(mockHttp.get).toHaveBeenCalledTimes(1);
+    expect(mockHttp.get.mock.calls[0]).toContainEqual({ headers });
+
+    expect(mockHttp.post).toHaveBeenCalledTimes(1);
+    expect(mockHttp.post.mock.calls[0]).toContainEqual({ headers });
+
+    done();
+  });
+
+  test('login sends expected data', async (done) => {
+    await RootAPI.login('foo', 'bar');
+    await RootAPI.login('foo', 'bar', 'baz');
+
+    expect(mockHttp.post).toHaveBeenCalledTimes(2);
+    expect(mockHttp.post.mock.calls[0]).toContainEqual('username=foo&password=bar&next=%2Fapi%2Fv2%2Fconfig%2F');
+    expect(mockHttp.post.mock.calls[1]).toContainEqual('username=foo&password=bar&next=baz');
+
+    done();
+  });
+
+  test('logout calls expected http method', async (done) => {
+    await RootAPI.logout();
+
+    expect(mockHttp.get).toHaveBeenCalledTimes(1);
+
+    done();
+  });
+});