add masonry grid item tests

webapp/components/MasonryGrid/MasonryGridItem.spec.js

@@ -0,0 +1,27 @@
+import { mount } from '@vue/test-utils'
+import MasonryGridItem from './MasonryGridItem'
+
+describe('MasonryGridItem', () => {
+  let wrapper
+
+  beforeEach(() => {
+    wrapper = mount(MasonryGridItem)
+    wrapper.vm.$parent.$emit = jest.fn()
+  })
+
+  it('emits "calculating-item-height" when starting calculation', async () => {
+    wrapper.vm.calculateItemHeight()
+    await wrapper.vm.$nextTick()
+
+    const firstCallArgument = wrapper.vm.$parent.$emit.mock.calls[0][0]
+    expect(firstCallArgument).toBe('calculating-item-height')
+  })
+
+  it('emits "finished-calculating-item-height" after the calculation', async () => {
+    wrapper.vm.calculateItemHeight()
+    await wrapper.vm.$nextTick()
+
+    const secondCallArgument = wrapper.vm.$parent.$emit.mock.calls[1][0]
+    expect(secondCallArgument).toBe('finished-calculating-item-height')
+  })
+})