Merge pull request #13 from oslabs-beta/rydang/jest-index

jest tests

Author: joshua0308

__tests__/index.test.js

@@ -0,0 +1,28 @@
+const index = require('../package/index');
+
+jest.mock('../package/timeJump');
+
+describe('unit testing for index.js', () => {
+  test('index.js should be exporting the linkState and timeJump methods', () => {
+    expect(typeof index.linkState).toBe('function');
+    expect(typeof index.timeJump).toBe('function');
+  });
+
+  test('index.js should be listening to the window for the jumpToSnap message', (done) => {
+    const calls = 10;
+    let count = 0;
+    global.addEventListener('message', ({ data: { action } }) => {
+      if (action === 'jumpToSnap') {
+        count += 1;
+        // timeJump should be called everytime a message is received
+        expect(index.timeJump.mock.calls.length).toBe(count);
+
+        // test is done once all messages have been received
+        if (count === calls) done();
+      }
+    });
+
+    // iterate ${calls} amount of times
+    [...Array(calls).keys()].forEach(() => global.postMessage({ action: 'jumpToSnap', payload: ['test'] }, '*'));
+  });
+});