Add test for from component

ui/mocks/ifql/apis/index.ts

@@ -2,3 +2,6 @@ jest.mock('src/utils/ajax', () => require('mocks/utils/ajax'))
 
 export const getSuggestions = jest.fn(() => Promise.resolve([]))
 export const getAST = jest.fn(() => Promise.resolve({}))
+export const getDatabases = jest.fn(() =>
+  Promise.resolve(['db1', 'db2', 'db3'])
+)

ui/test/ifql/components/From.test.tsx

@@ -0,0 +1,29 @@
+import React from 'react'
+import {shallow} from 'enzyme'
+import From from 'src/ifql/components/From'
+
+jest.mock('src/ifql/apis', () => require('mocks/ifql/apis'))
+
+const setup = () => {
+  const props = {
+    funcID: '1',
+    argKey: 'db',
+    value: 'db1',
+    onChangeArg: () => {},
+  }
+
+  const wrapper = shallow(<From {...props} />)
+
+  return {
+    wrapper,
+  }
+}
+
+describe('IFQL.Components.From', () => {
+  describe('rendering', () => {
+    it('renders without errors', () => {
+      const {wrapper} = setup()
+      expect(wrapper.exists()).toBe(true)
+    })
+  })
+})