7.fb0ed86b.js

(window.webpackJsonp=window.webpackJsonp||[]).push([[7],{206:function(t,s,a){"use strict";a.r(s);var n=a(28),e=Object(n.a)({},(function(){var t=this,s=t.$createElement,a=t._self._c||s;return a("ContentSlotsDistributor",{attrs:{"slot-key":t.$parent.slotKey}},[a("h1",{attrs:{id:"a-crash-course"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#a-crash-course"}},[t._v("#")]),t._v(" A Crash Course")]),t._v(" "),a("p",[t._v("Let's jump right into it, and learn Vue Test Utils (VTU) by building a simple Todo app, and writing tests as we go. This\nguide will cover:")]),t._v(" "),a("ul",[a("li",[t._v("mounting components")]),t._v(" "),a("li",[t._v("finding elements")]),t._v(" "),a("li",[t._v("filling out forms")]),t._v(" "),a("li",[t._v("triggering events")])]),t._v(" "),a("p",[t._v("A working repository with this example can be found "),a("a",{attrs:{href:"https://github.com/lmiller1990/vtu-next-demo",target:"_blank",rel:"noopener noreferrer"}},[t._v("here"),a("OutboundLink")],1),t._v(". The component file is "),a("a",{attrs:{href:"https://github.com/lmiller1990/vtu-next-demo/blob/master/src/TodoApp.vue",target:"_blank",rel:"noopener noreferrer"}},[t._v("here"),a("OutboundLink")],1),t._v(" and the the test is "),a("a",{attrs:{href:"https://github.com/lmiller1990/vtu-next-demo/blob/master/src/TodoApp.spec.js",target:"_blank",rel:"noopener noreferrer"}},[t._v("here"),a("OutboundLink")],1),t._v(".")]),t._v(" "),a("h2",{attrs:{id:"getting-started"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#getting-started"}},[t._v("#")]),t._v(" Getting Started")]),t._v(" "),a("p",[t._v("We will start off with a simple "),a("code",[t._v("TodoApp")]),t._v(" component with a single todo:")]),t._v(" "),a("div",{staticClass:"language-vue extra-class"},[a("pre",{pre:!0,attrs:{class:"language-vue"}},[a("code",[a("span",{pre:!0,attrs:{class:"token tag"}},[a("span",{pre:!0,attrs:{class:"token tag"}},[a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("<")]),t._v("template")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(">")])]),t._v("\n  "),a("span",{pre:!0,attrs:{class:"token tag"}},[a("span",{pre:!0,attrs:{class:"token tag"}},[a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("<")]),t._v("div")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(">")])]),t._v("\n  "),a("span",{pre:!0,attrs:{class:"token tag"}},[a("span",{pre:!0,attrs:{class:"token tag"}},[a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("</")]),t._v("div")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(">")])]),t._v("\n"),a("span",{pre:!0,attrs:{class:"token tag"}},[a("span",{pre:!0,attrs:{class:"token tag"}},[a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("</")]),t._v("template")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(">")])]),t._v("\n\n"),a("span",{pre:!0,attrs:{class:"token tag"}},[a("span",{pre:!0,attrs:{class:"token tag"}},[a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("<")]),t._v("script")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(">")])]),a("span",{pre:!0,attrs:{class:"token script"}},[a("span",{pre:!0,attrs:{class:"token language-javascript"}},[t._v("\n"),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("export")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("default")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n  name"),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v(":")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token string"}},[t._v("'TodoApp'")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(",")]),t._v("\n\n  "),a("span",{pre:!0,attrs:{class:"token function"}},[t._v("data")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n    "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("return")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n      todos"),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v(":")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("[")]),t._v("\n        "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n          id"),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v(":")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token number"}},[t._v("1")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(",")]),t._v("\n          text"),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v(":")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token string"}},[t._v("'Learn Vue.js 3'")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(",")]),t._v("\n          completed"),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v(":")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token boolean"}},[t._v("false")]),t._v("\n        "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("\n      "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("]")]),t._v("\n    "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("\n  "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("\n"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("\n")])]),a("span",{pre:!0,attrs:{class:"token tag"}},[a("span",{pre:!0,attrs:{class:"token tag"}},[a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("</")]),t._v("script")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(">")])]),t._v("\n")])])]),a("h2",{attrs:{id:"the-first-test-a-todo-is-rendered"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#the-first-test-a-todo-is-rendered"}},[t._v("#")]),t._v(" The first test - a todo is rendered")]),t._v(" "),a("p",[t._v("The first test we will write verifies a todo is rendered. Let's see the test first, then discuss each part:")]),t._v(" "),a("div",{staticClass:"language-js extra-class"},[a("pre",{pre:!0,attrs:{class:"language-js"}},[a("code",[a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("import")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v(" mount "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("from")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token string"}},[t._v("'@vue/test-utils'")]),t._v("\n"),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("import")]),t._v(" TodoApp "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("from")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token string"}},[t._v("'./TodoApp.vue'")]),t._v("\n\n"),a("span",{pre:!0,attrs:{class:"token function"}},[t._v("test")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token string"}},[t._v("'renders a todo'")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(",")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=>")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n  "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("const")]),t._v(" wrapper "),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token function"}},[t._v("mount")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),t._v("TodoApp"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v("\n\n  "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("const")]),t._v(" todo "),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" wrapper"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),a("span",{pre:!0,attrs:{class:"token function"}},[t._v("find")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token string"}},[t._v("'[data-test=\"todo\"]'")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v("\n\n  "),a("span",{pre:!0,attrs:{class:"token function"}},[t._v("expect")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),t._v("todo"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),a("span",{pre:!0,attrs:{class:"token function"}},[t._v("text")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),a("span",{pre:!0,attrs:{class:"token function"}},[t._v("toBe")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token string"}},[t._v("'Learn Vue.js 3'")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v("\n"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v("\n")])])]),a("p",[t._v("We start off by importing "),a("code",[t._v("mount")]),t._v(" - this is the main way to render a component in VTU. You declare a test by using the "),a("code",[t._v("test")]),t._v(" function with a short description of the test. The "),a("code",[t._v("test")]),t._v(" and "),a("code",[t._v("expect")]),t._v(" functions are globally available in most test runners (this example uses "),a("a",{attrs:{href:"https://jestjs.io/en/",target:"_blank",rel:"noopener noreferrer"}},[t._v("Jest"),a("OutboundLink")],1),t._v("). If "),a("code",[t._v("test")]),t._v(" and "),a("code",[t._v("expect")]),t._v(" look confusing, the Jest documentation has a "),a("a",{attrs:{href:"https://jestjs.io/docs/en/getting-started",target:"_blank",rel:"noopener noreferrer"}},[t._v("more simple example"),a("OutboundLink")],1),t._v(" of how to use them and how they work.")]),t._v(" "),a("p",[t._v("Next, we call "),a("code",[t._v("mount")]),t._v(" and pass the component as the first argument - this is something almost every test you write will do. By convention, we assign the result to a variable called "),a("code",[t._v("wrapper")]),t._v(", since "),a("code",[t._v("mount")]),t._v(' provides a simple "wrapper" around the app with some convinient methods for testing.')]),t._v(" "),a("p",[t._v("Finally, we use another global function common to many tests runner - Jest included - "),a("code",[t._v("expect")]),t._v(". The idea is we are asserting, or "),a("em",[t._v("expecting")]),t._v(", the actual output to match what we think it should be. In this case, we are finding an element with the selector "),a("code",[t._v('data-test="todo"')]),t._v(" - in the DOM, this will look like "),a("code",[t._v('<div data-test="todo">...</div>')]),t._v(". We then call the "),a("code",[t._v("text")]),t._v(" method to get the content, which we expect to be "),a("code",[t._v("'Learn Vue.js 3'")]),t._v(".")]),t._v(" "),a("blockquote",[a("p",[t._v("Using "),a("code",[t._v("data-test")]),t._v(" selectors is not required, but it can make your tests less brittle. classes and ids tend to change or move around as an application grows - by using "),a("code",[t._v("data-test")]),t._v(", it's clear to other developers which elements are used in tests, and should not be changed.")])]),t._v(" "),a("h2",{attrs:{id:"making-the-test-pass"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#making-the-test-pass"}},[t._v("#")]),t._v(" Making the test pass")]),t._v(" "),a("p",[t._v("If we run this test now, it fails with the following error message: "),a("code",[t._v("Cannot call text on an empty wrapper")]),t._v(". That's because we aren't rendering any todos, so the "),a("code",[t._v("find")]),t._v(' call is failing to return a wrapper (remember, VTU wraps all components, and DOM elements, in a "wrapper" with some convinient methods). Let\'s update '),a("code",[t._v("<template>")]),t._v(" in "),a("code",[t._v("TodoApp.vue")]),t._v(" to render the "),a("code",[t._v("todos")]),t._v(" array:")]),t._v(" "),a("div",{staticClass:"language-vue extra-class"},[a("pre",{pre:!0,attrs:{class:"language-vue"}},[a("code",[a("span",{pre:!0,attrs:{class:"token tag"}},[a("span",{pre:!0,attrs:{class:"token tag"}},[a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("<")]),t._v("template")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(">")])]),t._v("\n  "),a("span",{pre:!0,attrs:{class:"token tag"}},[a("span",{pre:!0,attrs:{class:"token tag"}},[a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("<")]),t._v("div")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(">")])]),t._v("\n    "),a("span",{pre:!0,attrs:{class:"token tag"}},[a("span",{pre:!0,attrs:{class:"token tag"}},[a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("<")]),t._v("div")]),t._v("\n      "),a("span",{pre:!0,attrs:{class:"token attr-name"}},[t._v("v-for")]),a("span",{pre:!0,attrs:{class:"token attr-value"}},[a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("=")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v('"')]),t._v("todo in todos"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v('"')])]),t._v("\n      "),a("span",{pre:!0,attrs:{class:"token attr-name"}},[t._v(":key")]),a("span",{pre:!0,attrs:{class:"token attr-value"}},[a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("=")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v('"')]),t._v("todo.id"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v('"')])]),t._v("\n      "),a("span",{pre:!0,attrs:{class:"token attr-name"}},[t._v("data-test")]),a("span",{pre:!0,attrs:{class:"token attr-value"}},[a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("=")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v('"')]),t._v("todo"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v('"')])]),t._v("\n    "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(">")])]),t._v("\n      {{ todo.text }}\n    "),a("span",{pre:!0,attrs:{class:"token tag"}},[a("span",{pre:!0,attrs:{class:"token tag"}},[a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("</")]),t._v("div")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(">")])]),t._v("\n  "),a("span",{pre:!0,attrs:{class:"token tag"}},[a("span",{pre:!0,attrs:{class:"token tag"}},[a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("</")]),t._v("div")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(">")])]),t._v("\n"),a("span",{pre:!0,attrs:{class:"token tag"}},[a("span",{pre:!0,attrs:{class:"token tag"}},[a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("</")]),t._v("template")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(">")])]),t._v("\n")])])]),a("p",[t._v("With this change, the test is passing. Congratulations! You wrote your first component test.")]),t._v(" "),a("h2",{attrs:{id:"adding-a-new-todo"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#adding-a-new-todo"}},[t._v("#")]),t._v(" Adding a new todo")]),t._v(" "),a("p",[t._v("The next feature we will be adding is for the user to be able to create a new todo. To do so, we need a form with an input for the user to type some text. When the user submits the form, we expect the new todo to be rendered. Let's take a look at the test:")]),t._v(" "),a("div",{staticClass:"language-js extra-class"},[a("pre",{pre:!0,attrs:{class:"language-js"}},[a("code",[a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("import")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v(" mount "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("from")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token string"}},[t._v("'@vue/test-utils'")]),t._v("\n"),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("import")]),t._v(" TodoApp "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("from")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token string"}},[t._v("'./TodoApp.vue'")]),t._v("\n\n"),a("span",{pre:!0,attrs:{class:"token function"}},[t._v("test")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token string"}},[t._v("'creates a 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As previously, let's start with the failing test:")]),t._v(" "),a("div",{staticClass:"language-js extra-class"},[a("pre",{pre:!0,attrs:{class:"language-js"}},[a("code",[a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("import")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v(" mount "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("from")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token string"}},[t._v("'@vue/test-utils'")]),t._v("\n"),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("import")]),t._v(" TodoApp "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("from")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token string"}},[t._v("'./TodoApp.vue'")]),t._v("\n\n"),a("span",{pre:!0,attrs:{class:"token function"}},[t._v("test")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token string"}},[t._v("'completes a todo'")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(",")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("async")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=>")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n  "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("const")]),t._v(" wrapper "),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token function"}},[t._v("mount")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),t._v("TodoApp"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v("\n\n  "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("await")]),t._v(" wrapper"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),a("span",{pre:!0,attrs:{class:"token function"}},[t._v("find")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token string"}},[t._v("'[data-test=\"todo-checkbox\"]'")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),a("span",{pre:!0,attrs:{class:"token function"}},[t._v("setValue")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token boolean"}},[t._v("true")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v("\n\n  "),a("span",{pre:!0,attrs:{class:"token function"}},[t._v("expect")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),t._v("wrapper"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),a("span",{pre:!0,attrs:{class:"token function"}},[t._v("find")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token string"}},[t._v("'[data-test=\"todo\"]'")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),a("span",{pre:!0,attrs:{class:"token function"}},[t._v("classes")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),a("span",{pre:!0,attrs:{class:"token function"}},[t._v("toContain")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token string"}},[t._v("'completed'")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v("\n"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v("\n")])])]),a("p",[t._v("This test is similar to the previous two; we find an element and interact with it in same way (we use "),a("code",[t._v("setValue")]),t._v(" again, since we are interacting with a "),a("code",[t._v("<input>")]),t._v(").")]),t._v(" "),a("p",[t._v("Lastly, we make an assertion. 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You wrote your first component tests.")]),t._v(" "),a("h2",{attrs:{id:"arrange-act-assert"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#arrange-act-assert"}},[t._v("#")]),t._v(" Arrange, Act, Assert")]),t._v(" "),a("p",[t._v("You may have noticed some new lines between the code in each of the tests. 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