add sqlEditor test; refactoring

tests/unit/components/SqlEditor.spec.js

@@ -0,0 +1,11 @@
+import { expect } from 'chai'
+import { mount } from '@vue/test-utils'
+import SqlEditor from '@/components/SqlEditor.vue'
+
+describe('SqlEditor.vue', () => {
+  it('Emits input event when a query is changed', async() => {
+    const wrapper = mount(SqlEditor)
+    await wrapper.findComponent({ name: 'codemirror'}).vm.$emit('input', 'SELECT * FROM foo')
+    expect(wrapper.emitted('input')[0]).to.eql(['SELECT * FROM foo'])
+  })
+})