Add a Async Select that fetches options from given endpoint (#1909)

* Add a Async Select that fetches options from given endpoint

* update it statement

superset/assets/spec/javascripts/components/AsyncSelect_spec.jsx

@@ -1,34 +1,35 @@
 import React from 'react';
 import Select from 'react-select';
-import DatabaseSelect from '../../../javascripts/SqlLab/components/DatabaseSelect';
+import AsyncSelect from '../../../javascripts/components/AsyncSelect';
 import { shallow } from 'enzyme';
 import { describe, it } from 'mocha';
 import { expect } from 'chai';
 import sinon from 'sinon';
 
-describe('DatabaseSelect', () => {
+describe('AsyncSelect', () => {
   const mockedProps = {
-    actions: {},
+    dataEndpoint: '/slicemodelview/api/read',
+    onChange: sinon.spy(),
+    mutator: () => {},
   };
   it('is valid element', () => {
     expect(
-      React.isValidElement(<DatabaseSelect {...mockedProps} />)
+      React.isValidElement(<AsyncSelect {...mockedProps} />)
     ).to.equal(true);
   });
 
   it('has one select', () => {
     const wrapper = shallow(
-      <DatabaseSelect {...mockedProps} />
+      <AsyncSelect {...mockedProps} />
     );
     expect(wrapper.find(Select)).to.have.length(1);
   });
 
   it('calls onChange on select change', () => {
-    const onChange = sinon.spy();
     const wrapper = shallow(
-      <DatabaseSelect onChange={onChange} />
+      <AsyncSelect {...mockedProps} />
     );
     wrapper.find(Select).simulate('change', { value: 1 });
-    expect(onChange).to.have.property('callCount', 1);
+    expect(mockedProps.onChange).to.have.property('callCount', 1);
   });
 });

superset/assets/spec/javascripts/sqllab/QuerySearch_spec.jsx

@@ -18,14 +18,8 @@ describe('QuerySearch', () => {
   });
   const wrapper = shallow(<QuerySearch {...mockedProps} />);
 
-  it('should have four Select', () => {
-    expect(wrapper.find(Select)).to.have.length(4);
-  });
-
-  it('updates userId on user selects change', () => {
-    wrapper.find('[name="select-user"]')
-      .simulate('change', { value: 1 });
-    expect(wrapper.state().userId).to.equal(1);
+  it('should have three Select', () => {
+    expect(wrapper.find(Select)).to.have.length(3);
   });
 
   it('updates fromTime on user selects from time', () => {