[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/sqllab/ExploreResultsButton_spec.jsx

@@ -3,7 +3,6 @@ import configureStore from 'redux-mock-store';
 import thunk from 'redux-thunk';
 
 import { shallow } from 'enzyme';
-import { expect } from 'chai';
 import sinon from 'sinon';
 
 import $ from 'jquery';
@@ -65,13 +64,13 @@ describe('ExploreResultsButton', () => {
     }).dive());
 
   it('renders', () => {
-    expect(React.isValidElement(<ExploreResultsButton />)).to.equal(true);
+    expect(React.isValidElement(<ExploreResultsButton />)).toBe(true);
   });
 
   it('renders with props', () => {
     expect(
       React.isValidElement(<ExploreResultsButton {...mockedProps} />),
-    ).to.equal(true);
+    ).toBe(true);
   });
 
   it('detects bad columns', () => {
@@ -82,15 +81,15 @@ describe('ExploreResultsButton', () => {
     });
 
     const badCols = wrapper.instance().getInvalidColumns();
-    expect(badCols).to.deep.equal(['COUNT(*)', '1', '123', 'CASE WHEN 1=1 THEN 1 ELSE 0 END']);
+    expect(badCols).toEqual(['COUNT(*)', '1', '123', 'CASE WHEN 1=1 THEN 1 ELSE 0 END']);
 
     const msgWrapper = shallow(wrapper.instance().renderInvalidColumnMessage());
-    expect(msgWrapper.find('div')).to.have.length(1);
+    expect(msgWrapper.find('div')).toHaveLength(1);
   });
 
   it('renders a Button', () => {
     const wrapper = getExploreResultsButtonWrapper();
-    expect(wrapper.find(Button)).to.have.length(1);
+    expect(wrapper.find(Button)).toHaveLength(1);
   });
 
   describe('datasourceName', () => {
@@ -107,19 +106,19 @@ describe('ExploreResultsButton', () => {
     it('should generate data source name from query', () => {
       const sampleQuery = queries[0];
       const name = wrapper.instance().datasourceName();
-      expect(name).to.equal(`${sampleQuery.user}-${sampleQuery.tab}-abcd`);
+      expect(name).toBe(`${sampleQuery.user}-${sampleQuery.tab}-abcd`);
     });
     it('should generate data source name with empty query', () => {
       wrapper.setProps({ query: {} });
       const name = wrapper.instance().datasourceName();
-      expect(name).to.equal('undefined-abcd');
+      expect(name).toBe('undefined-abcd');
     });
 
     it('should build viz options', () => {
       wrapper.setState({ chartType: mockChartTypeTB });
       const spy = sinon.spy(wrapper.instance(), 'buildVizOptions');
       wrapper.instance().buildVizOptions();
-      expect(spy.returnValues[0]).to.deep.equal({
+      expect(spy.returnValues[0]).toEqual({
         schema: 'test_schema',
         sql: wrapper.instance().props.query.sql,
         dbId: wrapper.instance().props.query.dbId,
@@ -141,7 +140,7 @@ describe('ExploreResultsButton', () => {
       context: { store },
     }).dive();
     const inst = longQueryWrapper.instance();
-    expect(inst.getQueryDuration()).to.equal(100.7050400390625);
+    expect(inst.getQueryDuration()).toBe(100.7050400390625);
   });
 
   describe('visualize', () => {
@@ -173,12 +172,12 @@ describe('ExploreResultsButton', () => {
 
     it('should build request', () => {
       wrapper.instance().visualize();
-      expect(ajaxSpy.callCount).to.equal(1);
+      expect(ajaxSpy.callCount).toBe(1);
 
       const spyCall = ajaxSpy.getCall(0);
-      expect(spyCall.args[0].type).to.equal('POST');
-      expect(spyCall.args[0].url).to.equal('/superset/sqllab_viz/');
-      expect(spyCall.args[0].data.data).to.equal(JSON.stringify(mockOptions));
+      expect(spyCall.args[0].type).toBe('POST');
+      expect(spyCall.args[0].url).toBe('/superset/sqllab_viz/');
+      expect(spyCall.args[0].data.data).toBe(JSON.stringify(mockOptions));
     });
     it('should open new window', () => {
       const infoToastSpy = sinon.spy();
@@ -197,9 +196,9 @@ describe('ExploreResultsButton', () => {
       });
 
       wrapper.instance().visualize();
-      expect(exploreUtils.exportChart.callCount).to.equal(1);
-      expect(exploreUtils.exportChart.getCall(0).args[0].datasource).to.equal('107__table');
-      expect(infoToastSpy.callCount).to.equal(1);
+      expect(exploreUtils.exportChart.callCount).toBe(1);
+      expect(exploreUtils.exportChart.getCall(0).args[0].datasource).toBe('107__table');
+      expect(infoToastSpy.callCount).toBe(1);
     });
     it('should add error toast', () => {
       const dangerToastSpy = sinon.spy();
@@ -219,8 +218,8 @@ describe('ExploreResultsButton', () => {
       });
 
       wrapper.instance().visualize();
-      expect(exploreUtils.exportChart.callCount).to.equal(0);
-      expect(dangerToastSpy.callCount).to.equal(1);
+      expect(exploreUtils.exportChart.callCount).toBe(0);
+      expect(dangerToastSpy.callCount).toBe(1);
     });
   });
 });