[refactor] Migrate from Mocha+Chai to Jest (#6079)

* [refactor] Migrate from Mocha+Chai to Jest

This change migrates all the existing unit tests
- to Jest's global expect and matchers from chai's imported expect, asserts and matchers.
- to Jest's describe/test from mocha's describe/it

The majority of the mechanical changes to tests are achieved through running jest-codemods. The only two note-worthy manual tweaks:
1. Setting a testURL of http://localhost in jest config and adjusting a few tests to leverage this value instead of relying on about:blank.
2. Re-enabling ExploreChartPanel_spec which was previously commented out as we cannot have empty tests with nothing in it with Jest. :)

This change also removes dependencies to Mocha and Chai.

* Remove the test:one command as it now does the same thing as test.

* Fixing lint errors. The diff looks large but is large done through `yarn run lint --fix`

The only noteworthy change is the one in eslintrc for tests. The env has been updated from mocha to jest.

* Adding eslint-plugin-jest and further modify tests.

- One small fix in sqllab's Timer Spec for a test that is not using the spy it created for testing.
- Deletion of a duplicated test caught by eslint-plugin-jest.

* - Make istanbul coverage work with Jest.

- Remove dependency on stand-alone istanbul and babel-istanbul as they're built-into jest. Yes!

* Attempt to fix dynamic imports in tests.

* run sequentially and log heap usage

* - tweaking maxworkers for travis and specifying coverageDirectory for codecov

- remove dynamic import in shim.js now that it is set in babelrc for tests only.

superset/assets/spec/javascripts/messageToasts/components/ToastPresenter_spec.jsx

@@ -1,6 +1,5 @@
 import React from 'react';
 import { shallow } from 'enzyme';
-import { expect } from 'chai';
 
 import mockMessageToasts from '../mockMessageToasts';
 import Toast from '../../../../src/messageToasts/components/Toast';
@@ -19,12 +18,12 @@ describe('ToastPresenter', () => {
 
   it('should render a div with class toast-presenter', () => {
     const wrapper = setup();
-    expect(wrapper.find('.toast-presenter')).to.have.length(1);
+    expect(wrapper.find('.toast-presenter')).toHaveLength(1);
   });
 
   it('should render a Toast for each toast object', () => {
     const wrapper = setup();
-    expect(wrapper.find(Toast)).to.have.length(props.toasts.length);
+    expect(wrapper.find(Toast)).toHaveLength(props.toasts.length);
   });
 
   it('should pass removeToast to the Toast component', () => {
@@ -35,6 +34,6 @@ describe('ToastPresenter', () => {
         .find(Toast)
         .first()
         .prop('onCloseToast'),
-    ).to.equal(removeToast);
+    ).toBe(removeToast);
   });
 });

superset/assets/spec/javascripts/messageToasts/components/Toast_spec.jsx

@@ -1,7 +1,6 @@
 import { Alert } from 'react-bootstrap';
 import React from 'react';
 import { shallow } from 'enzyme';
-import { expect } from 'chai';
 
 import mockMessageToasts from '../mockMessageToasts';
 import Toast from '../../../../src/messageToasts/components/Toast';
@@ -19,24 +18,24 @@ describe('Toast', () => {
 
   it('should render an Alert', () => {
     const wrapper = setup();
-    expect(wrapper.find(Alert)).to.have.length(1);
+    expect(wrapper.find(Alert)).toHaveLength(1);
   });
 
   it('should render toastText within the alert', () => {
     const wrapper = setup();
     const alert = wrapper.find(Alert).dive();
 
-    expect(alert.childAt(1).text()).to.equal(props.toast.text);
+    expect(alert.childAt(1).text()).toBe(props.toast.text);
   });
 
   it('should call onCloseToast upon alert dismissal', done => {
     const onCloseToast = id => {
-      expect(id).to.equal(props.toast.id);
+      expect(id).toBe(props.toast.id);
       done();
     };
     const wrapper = setup({ onCloseToast });
     const handleClosePress = wrapper.instance().handleClosePress;
-    expect(wrapper.find(Alert).prop('onDismiss')).to.equal(handleClosePress);
+    expect(wrapper.find(Alert).prop('onDismiss')).toBe(handleClosePress);
     handleClosePress(); // there is a timeout for onCloseToast to be called
   });
 });

superset/assets/spec/javascripts/messageToasts/reducers/messageToasts_spec.js

@@ -1,11 +1,9 @@
-import { expect } from 'chai';
-
 import { ADD_TOAST, REMOVE_TOAST } from '../../../../src/messageToasts/actions';
 import messageToastsReducer from '../../../../src/messageToasts/reducers';
 
 describe('messageToasts reducer', () => {
   it('should return initial state', () => {
-    expect(messageToastsReducer(undefined, {})).to.deep.equal([]);
+    expect(messageToastsReducer(undefined, {})).toEqual([]);
   });
 
   it('should add a toast', () => {
@@ -14,15 +12,15 @@ describe('messageToasts reducer', () => {
         type: ADD_TOAST,
         payload: { text: 'test', id: 'id', type: 'test_type' },
       }),
-    ).to.deep.equal([{ text: 'test', id: 'id', type: 'test_type' }]);
+    ).toEqual([{ text: 'test', id: 'id', type: 'test_type' }]);
   });
 
-  it('should add a toast', () => {
+  it('should remove a toast', () => {
     expect(
       messageToastsReducer([{ id: 'id' }, { id: 'id2' }], {
         type: REMOVE_TOAST,
         payload: { id: 'id' },
       }),
-    ).to.deep.equal([{ id: 'id2' }]);
+    ).toEqual([{ id: 'id2' }]);
   });
 });

superset/assets/spec/javascripts/messageToasts/utils/getToastsFromPyFlashMessages_spec.js

@@ -1,5 +1,3 @@
-import { expect } from 'chai';
-
 import {
   DANGER_TOAST,
   INFO_TOAST,
@@ -11,14 +9,14 @@ import getToastsFromPyFlashMessages from '../../../../src/messageToasts/utils/ge
 describe('getToastsFromPyFlashMessages', () => {
   it('should return an info toast', () => {
     const toast = getToastsFromPyFlashMessages([['info', 'info test']])[0];
-    expect(toast).to.deep.include({ toastType: INFO_TOAST, text: 'info test' });
+    expect(toast).toMatchObject({ toastType: INFO_TOAST, text: 'info test' });
   });
 
   it('should return a success toast', () => {
     const toast = getToastsFromPyFlashMessages([
       ['success', 'success test'],
     ])[0];
-    expect(toast).to.deep.include({
+    expect(toast).toMatchObject({
       toastType: SUCCESS_TOAST,
       text: 'success test',
     });
@@ -26,7 +24,7 @@ describe('getToastsFromPyFlashMessages', () => {
 
   it('should return a danger toast', () => {
     const toast = getToastsFromPyFlashMessages([['danger', 'danger test']])[0];
-    expect(toast).to.deep.include({
+    expect(toast).toMatchObject({
       toastType: DANGER_TOAST,
       text: 'danger test',
     });