some cleaning and started to understand unittest with jest

test/specs/Posts.spec.js

@@ -0,0 +1,24 @@
+import { shallowMount } from '@vue/test-utils'
+import Posts from '@/components/Home/Posts'
+
+// https://alligator.io/vuejs/testing-vue-with-jest/
+
+function mountComponentWithProps (Component, propsData) {
+  const Constructor = Vue.extend(Component);
+  const vm = new Constructor({
+    propsData
+  }).$mount();
+
+  return vm.$el;
+}
+
+describe('Posts.vue', () => {
+  it('posts should not be empty', () => {
+    const PostsData = mountComponentWithProps(Posts, { all: [] });
+    const allData = PostData.all;
+
+    console.log(allData)
+
+    expect(allData).toBe([])
+  })
+})

test/specs/WelcomeMessage.spec.js

@@ -1,14 +0,0 @@
-import { shallowMount } from '@vue/test-utils'
-import WelcomeMessage from '@/components/Home/WelcomeMessage'
-
-describe('WelcomeMessage.vue', () => {
-  it('renders props.msg when passed', () => {
-    const name = 'tester'
-
-    const wrapper = shallowMount(WelcomeMessage, {
-      propsData: { name }
-    })
-
-    expect(wrapper.text()).toBe('Hello tester from my Vue.js page, built with Webpack 4!')
-  })
-})