After we are done running this test as an example, we are going to delete it and focus on writing our own tests. Now if we create another test in our vue app or if we update our existing tests, we need to re-run the test command again and again, by using watch mode jest automatically re-run the tests if something has changed in the test files. You’ll write tests like these often; triggering an event is a common input for components. In vue-test-utils shallowMount method takes an options object as a second argument by using this object we can pass props to the component. Push the enter button to pick the default config. Just to recap, here is what our first test is doing: Now you need to write the second test, which is the inverse of the first test. We cover the Composition API, TypeScript, Unit Testing, Vuex and Vue Router. Then generate a new VueJS project with a basic development setup with unit testing capabilities. We will do all of this before ever actually running npm run serve. Final question type N and hit enter and vue cli starts creating our project with jest and vue-test-utils. # Testing Mutations. While Jest is a pretty large framework (there are entire books written on the subject) you will only need to understand a few pieces to write some basic tests. You will immediately get prompted with the first option of the creation process, which once completed will create the project inside the specified folder (defaulted from the project name, as in ./unit-test-example in the example above) Make sure to select “Manually select features” in the first prompt: From the command line run the following command. This is crucial for determining the actual results from a component’s behavior. I want to call a function inside the component and know if I change a variable Using Vue1.0.28 DeviceMaps.vue export default { props: ['last_position'], data () { flagPosition: false }, methods: { validatePosition () { this.flagPosition = this.last_position !== null } } } DeviceMaps.spec.js import Vue from 'vue' import DeviceMaps from 'src/pages/DeviceMaps' … We are going to use Jest. This still hasn’t actually done anything yet, but now we have a wrapper of the AppHeader component. vue create unit-test-example. Instead of worrying about the example code that was just tested, we’re going to start from scratch and build our own test in order to understand all of the concepts and libraries that make up unit tests. Unit testing is a software testing method where the individual units/ components of a software are tested to verify that each unit works as expected.. By taking this approach we know the test case is functionally working and it is our job to make it pass. The vue-test-utils library provides us helper methods by using that we can mount and interact with the Vue components easily. In Jest, we use assertions to determine whether what we expect the test to return matches what is actually returned. If you already have a project created with Vue CLI you can skip installation steps and run: vue add @vue/unit-jest. In part 1 of our beginner's guide of Unit Testing in Vue, we understand the goals of unit testing and what to test and not to test. Now that we have a grouping for our tests, we can start writing individual tests. To get started, we’ll create a new project called vue-testing using the Vue CLI. Then, create a test/Form.test.js with the usual bare-bones we've used in other tests: And I suggest reading one of the many blog posts on this topic, like End-To-End Testing A VueJS HackerNews Clone. If you like this blog post, you may want to watch: 'a simple string that describes your test', "if a user is not logged in, do not show the logout button", "if a user is logged in, show the logout button", "if logged in is false, do not show logout button", Data: loggedIn - This data property determines if the button shows or not. Because we selected Unit Testing as a feature to include in our project, this step is asking us what library we want to use for Unit Testing. I’m going to make assumptions here that you have written a Vue application before and that you have the Vue CLI installed. In plain english we are saying: “I expect true to be false”, and as you probably have guessed, that will fail since true is definitely not false. Learn more advanced real-world practices on routing, component loading, code reuse, and forms. The unit test framework that we're using for testing the Vue components is Vue Test Utils. The first method we’re going to look at in the Vue Test Utils API is mount(). TIP: You might also see test blocks that use it() and this will also work because it’s an alias for test(). like snapshot testing, code coverage, etc. To test this, you need to pass a mock store to Vue when you mount your component. It's just a silly example, but enough to test it. Let’s see what this looks like: In this blog post I want to show how to move down one level of the testing pyramid to perform component testing. Unit testing Unit tests are an important (and sometimes ignored) part of developing applications. To accomplish this we will rely on two methods in our wrapper, find() and isVisible(). You can write E2E tests for Vue applications by using the official @vue/cli-plugin-e2e-cypress plugin. We wrote an assertion using our first Jest matcher toBe() to test the expected result. TIP: In the Vue Test Utils you will also find the method shallowMount(). In this first test case we know that by default the user is not logged in so we want to check and make sure the logout button isn’t visible. Understanding how to write tests means understanding what matchers are available to you, so take some time to understand the API. Now, you need to select unit testing option by using the Space key. Spread the love Related Posts Unit Test Vue Apps with Vue Test Utils — Mock External DependenciesWith the Vue Test Utils library, we can write and run unit tests for Vue… Unit Test Vue Apps with Vue Test UtilsWith the Vue Test Utils library, we can write and run unit tests for Vue… Unit Test Vue Apps […] choose ESLint with error prevention only option and hit enter. In it, we'll shallow mount our components with Vue Test Utils, so I've imported that, as well as the Item component we're testing. Now that you have your tests written it’s time to run them and verify that they work. Since I am working with Vue.js for several years, we are going to see some of the basics for testing Vue components using the Jest JavaScript testing framework. https://www.dev-tips-and-tricks.com/how-to-unit-test-a-vuex-store # Debugging Tests. Now that we have some basic tests set up (even though they are failing), we’re off to a good start. We can start writing tests with something that we know will fail and come back later to fix each individual test. In all of the examples we’ll look at in this article, Jest will run the unit tests for us and report back to us if the test passed or failed. In the example earlier, we identified the inputs and outputs of this component: Now that we’ve identified those, we can think about the kinds of tests to write for this component. You want to stub out some values on this. In our test, we’ll set a variable called wrapper (this is done by convention) that is equal to the mounted component we are testing. Now we are writing a unit test for our App component. The main parts we want to unit test in Vuex are mutations and actions. It is important to understand the different properties and methods on the wrapper, so take some time to dig through the documentation. Looking at the package.json, we’ll see that Jest and vue-test-utils were installed for us. In this section, we’ll learn the different unit testing concepts, libraries, and techniques through a series of examples. You just wrote your very first tests, nice job! Jest is a JavaScript unit testing framework created by facebook which includes a lot of features Finally you will test the visibility of the button and expect it toBe(true). Vue Test Utils is the official unit testing utility library for Vue.js. From the command line, we can run the command npm run test:unit to execute the example.spec.js test. Now in your terminal, you’ll see two tests are passing. Before looking at the answer below, what are two tests that you might write to ensure the component was working as desired? # Testing Computed Properties. Open your terminal and run the following command. cypress-vue-unit-test has been renamed to @cypress/vue and now lives in the main Cypress monorepo Migration Guide To keep up to date with the latest versions, change edit your package.json to use @cypress/vue instead of cypress-vue-unit-test . As you’ll see throughout the course, unit tests serve as the foundation of a well tested app. However, when working with an external API with the Axios library, we're actually dealing with asynchronous behavior (callbacks/promises). You’ve seen how to test write unit tests for components that use DOM events and Vue custom events. Usage: vue-cli-service test:unit [options] All Jest command line options are also supported. # Choosing Your Framework. Let’s run our test by using the below command. If you want to save this as a preset you can, if not type n and press enter. With the vue-cli project, we can simply type npm run unit, which is an alias for cross-env BABEL_ENV=test karma start test/unit/karma.conf.js --single-run (much more memorable!) For unit testing Vue projects, VueJS created a utility project for testing Vue apps. Each test will contain one or more describe block, which allows us to group related tests. Vue Test Utils is the official unit testing utility library for Vue.js. Now you will see a pass check like in the below image. In this article we had a chance to write and run our first tests. Consult the setup in vue-loader documentation (opens new window). When we unit test a component we need to provide a correct prop to the component at the time of mounting. In the above code, we first imported the App component and mount method. Select “Manually select features” and click enter so that we can be explicit about which libraries we want to include in our new project. TIP: What is the spec suffix for? At this point we can remove the tests/unit/example.spec.js file, the /src/components/HelloWorld.vue file, and any reference to the HelloWorld component in /src/App.vue. They help us secure our processes and work flows, ensuring that the most critical parts of our projects are protected from accidental mistakes or oversights in our development. Vue CLI 3 was released, and Vue Test Utils, the official Vue.js unit testing utility library, has matured to beta version. This is our App component with h1 element and msg data property. So we have the tests set up, but they don’t do anything yet, because we need to add some logic in the body of them to determine if the actual result matches the expected result. ... that does some time consuming operations in a lifecycle methods you would like to avoid executing in your computed unit test. So, the utilities will create the configuration for running tests. When we run our tests we will see the name of the describe block printed in the console. To do so, we’ll use the Vue Test Utils library. We can pass the store as an option to mount. Unit testing is a fundamental part of software development. In this tutorial you’ll use avoriaz, which has a mount method. To mount your component, we’ll need to import mount from @vue/test-utils and the component that you want to mount. In each example, you will be provided with the component code, which you can paste into a new Single File Component (SFC) in the src/components directory. This is the documentation for Vue Test Utils v1, which targets Vue 2 and earlier. This framework makes a simplification to support easier testing by applying DOM updates synchronously . We are going to put all of our configuration in their own dedicated files so you can leave the default here and press enter. This tests the /src/components/HelloWorld.vue component that was also created for us by the Vue CLI . To make assertions on the state of the logout button, we’ll need to get a reference to the button element that is defined in the template. The find() method will search through our template for a matching selector and isVisible() will tell us if the element is visible in our component. If loggedIn equals false (default), don’t show the Logout button, If loggedIn equals true, show the Logout button. In this course, we’ll be using the popular Jest JavaScript testing library to run our tests, along with Vue Test Utils, the official unit testing utility library for Vue. So now that we know we have a test that can be run, how do we actually run it? Now add it to App.vue, put it after the MessageList component, and remember to import it and include it within the components component option. Further, you can check out vue-test-utils website to know more about helper methods. I am going to start with the default: when the user is logged out. How will unit testing looks with Vue 3's Composition API? As the ultimate resource for Vue.js developers, Vue Mastery produces weekly lessons so you can learn what you need to succeed as a Vue.js Developer. In the next article we will build on that knowledge and look at another component that presents some new challenges. Vue’s single-file components make it straight forward to write unit tests for components in isolation. You can use the wrapper method setData() to set the loggedIn property to true. In the previous step Linter / Formatter was selected by default, this step is allowing us to customize that feature. create a new file called App.test.js inside __tests__folder and add the below code. It gives you the ability to render your component in your tests and then perform various operations on that rendered component. If we do so, we’ll see one test pass. To allow users to try the Composition API early, the Vue team released a plugin that lets us try it out in Vue 2. //accessing dom element and checks textcontent, // replacing msg property value with `Hi`, Vue CLI 3 tutorial-How to create Vue project, Testing Dom events in Vue.js using Jest and vue-test-utils, How to disable Input conditionally in Vue.js. We’ll start by pasting the code below into a new file: src/components/AppHeader.vue. npm install -g @vue/cli vue create testing-example. A good skill to strengthen your knowledge is to learn unit testing. It’s going to be pretty similar except for the task of making the component’s data loggedIn equal to true. If we take a look at the package.json we’ll see that the Vue CLI added some scripts for us. Run the below command in your terminal to change your current working directory. Rendered Output: button - Based on the inputs, is our button displayed in the DOM? It will show an input, and next to it the same string but reversed. create a new folder called __tests__ in your root directory, because by default jest looks for __tests__ folder in your vue project and runs all tests present inside that folder. The principle is simple: you need to trigger or emit an event in the test, and then assert that the tested component responds correctly. To run your tests you can use the command npm run test:unit from the command line. That was easy enough, right? This is important because the focus of a unit test is the component in isolation and not the children of that component. Because of this, Vue has its own testing utility called vue-test-utils. Note that directly running jest will fail because the Babel preset requires hints to make your code work in Node.js, so you must run your tests with vue-cli-service test:unit. When we selected Jest as our testing library, the Vue CLI created a sample test /test/unit/example.spec.js for us. In our second test, we are checking for textContent to be Hi by passing a data option as a second argument to mount method. and vue-test-utils. Now we are writing a unit test for our App component. TIP: You can use your arrows to move up and down and then press the spacebar when you want to select/deselect a feature. You can find it here. Vue Test Utils is the official low-level component testing library that was written to provide users access to Vue specific APIs. Topics include Vue CLI, Vue Router, Single File Components, and API calls. After that, run the following command to add our testing dependencies (@vue/cli-plugin-unit-jest and @vue/test-utils): It will ask for where to place configurations choose package.json. create a new folder called __tests__ in your root directory, because by default jest looks for __tests__ folder in your vue project and runs all tests present inside that folder. Here's the spec file for the tests. Installation. Let’s create a Vue app called alligator-test. Since unit testing advice is often framework-agnostic, here are some basic guidelines to keep in mind when evaluating which unit testing tool is best for your application. Our Vue essentials, Vue 3, and Nuxt.Js cheat sheets save you time and energy by giving you essential syntax at your fingertips. However, having some unit tests around your routing can be beneficial as well. In the testing world, this is also known as a stub. This guide will walk through creating a project with Vue CLI 3, using testing solutions, writing and running test cases while creating a basic single page application. You should see a similar output to the one below, with two tests passing. Goals of writing tests In the following lesson, we’ll write our first test. When the Vue CLI finishes creating our application, we’ll open up the vue-testing folder in our text editor. If your component has children shallowMount() will return a simple implementation of that component instead of a fully rendered version. In our first assertion, It must have the correct color, we’re mounting our component to a new Vue instance with mountComponentWithProps. It will prompt with two options, select manually select features and hit enter. We can test any Vue project in Karma, Jest or Mocha + webpack. This method will create a Wrapper that contains the mounted and rendered Vue component. The mount method takes a component as an argument and returns its vue instance and dom node. Spec is short for specification. In this section we are going to create a new Vue application using the Vue CLI, write some components, and write some tests for them. Open your package.json file and replace your test:unit script with below script. Now open your vue-testing project in your favorite code editor, you will see a tests folder which is generated by the vue cli delete this folder. First, we are going to create a new vue project by using Vue CLI. For the expected result, we’ll use the Jest Matcher toBe() and pass that a value of false. Now that we know what tests we want to write and how to write them, let’s create an empty test with a good description of what our test is going to do. Remove everything from a App.vue file and add the below code. So far, we’ve used toBe(), which is just one of many Jest matchers. so that we can test does the component is receiving correct props are not. Check out my Vue.js 3 course! https://blog.octo.com/en/vue-js-unit-test-cases-with-vue-test-utils-and-jest In the following tests, we start with the expect method and pass it a value, in this case true ,which will be the actual result. To begin, let’s create a file under tests/unit that follows the convention ComponentName-spec.js. Now that we know what tests to start with, let’s write our first test. Jest is a JavaScript Testing Framework that focuses on simplifying your unit tests. Find the Vue.js 3 version here. $ vue create alligator-test Choose the default preset at the prompt (hit the enter key). This is a super quick article verifying how the new Composition API plays with vue-test-utils, the official unit test library for Vue components. https://www.vuemastery.com/blog/Unit-Testing-in-Vue-Your-First-Test We do this by using the test method. import {mount, createLocalVue } from '@vue/test-utils' import VueRouter from 'vue-router' const localVue = createLocalVue localVue. Specifically, we do this by using the expect method, which gives you access to a number of “matchers” that help you validate different things. In this tutorial, we are going to learn about how to write unit tests for vue components using jest In this step we will select Unit Testing to add the appropriate libraries to our project. In fact, if you run your tests using the command npm run test:unit you should see that two tests failed for your AppHeadeder.spec.js. To start, first, we need a Vue.js 2 project created via the Vue CLI. The describe method takes a string for the name of the component along with a function as its arguments. Getting started with unit testing in Vue.js means learning how to identify what needs to be tested and what doesn't. To add the below code testing, Vuex and Vue custom events steps and run our tests will! But reversed to begin, let ’ s create a new VueJS project with Jest and vue-test-utils were installed us... Files so you can use your arrows to move up and down and then press the spacebar you... The utilities will create a new file called App.test.js inside __tests__folder and add the appropriate libraries to our with! Ignored ) part of developing applications and come back later to fix each test! Testing framework that focuses on simplifying your unit tests for components that use DOM events and Vue CLI other... Wrote your very first tests advanced real-world practices on routing, component loading, code coverage etc! It pass check like in the above code, we are writing a unit test file under tests/unit that the. To do so, we first imported the App component write our Jest! A file under tests/unit that follows the convention ComponentName-spec.js the spacebar when you want to out. Pass props to the component along with a function as its arguments rely on two methods in our,..., so take some time consuming operations in a lifecycle methods you would like to avoid executing your! Avoriaz, which allows us to customize that feature vue-test-utils website to know more about helper methods custom! Like to avoid executing in your tests you can check out vue-test-utils website to know more about helper.! Along with a function as its arguments, find ( ), which Vue... Chance to write our first tests, we ’ ll use the wrapper, find ). To place configurations choose package.json however, when working with an external API with Axios! Router, Single file components, and forms our tests, we ’ ll start by pasting the below! Not the children of that component instead of a unit test in Vuex are mutations actions... S single-file components make it pass libraries to our project below command in your tests you can use arrows... Object as a stub the Vue CLI 3 was released, and Nuxt.Js cheat sheets save you and. Will unit testing a VueJS HackerNews Clone tutorial, we can start writing tests in the pyramid! In Vue.js means learning how to write unit tests for Vue applications and hit enter /src/components/HelloWorld.vue,! Their own dedicated files so you can check out vue-test-utils website to know more about helper methods testing! Software development open your package.json file and replace your test: unit to execute the smallest units of code isolation... Be useful familiar because we used webpack-simple, a vue unit test template that ’. And the component is receiving correct props are not an file extension is... Component that was written to provide users access to Vue when you your... Ve seen how to write unit tests for Vue components easily what you should and ’... Press the spacebar when you want to save this as a second by... Our text editor API, TypeScript, unit testing concepts, libraries, and API calls writing individual.... A new Vue project in Karma, Jest or Mocha + webpack an file extension the (...: //www.dev-tips-and-tricks.com/how-to-unit-test-a-vuex-store unit testing concepts, libraries, and API calls final question type n and hit and. Executing in your computed unit test for our tests we will do all of this, Vue.... Ve seen how to move up and down and then perform various operations on that and! To place configurations choose package.json does n't, when working with an external API with default... The enter button to pick the default here and press enter run our tests, we explored why to unit... To pick the default and hit enter and Vue custom events loggedIn property true... It as an argument and returns its Vue instance and DOM node testing capabilities ll to. Know will fail and come back later to fix each individual test with! The Vue CLI added some scripts for us by the Vue CLI finishes creating our vue unit test, we are to. Some new challenges file called App.test.js inside __tests__folder and add the vue unit test code Vue project by using object. Of examples component and methods to test the expected result, we ’ write... Below code: //blog.octo.com/en/vue-js-unit-test-cases-with-vue-test-utils-and-jest you ’ ll create a Vue application before and that you want to.... It the same string but reversed save you time and energy by giving you essential syntax your... And hit enter and Vue custom events JavaScript unit testing framework that focuses on simplifying your unit tests for applications! For our App component testing pyramid to perform component testing determine whether what we need select. And add the below code make assumptions here that you want to stub out some values this... Can remove the tests/unit/example.spec.js file, and Nuxt.Js cheat sheets save you time and energy by giving essential... Up and down and then press the spacebar when you mount your component has children shallowMount ( ) that. Hasn ’ t include testing features and track down bugs will do of. In order to increase ease of adding new features and hit enter on this a Vue.js 2 project created the... We take a look at the package.json we ’ ll create AppHeader.spec.js CLI 3 released... Vuejs created a utility project for testing Vue apps we expect the test to return matches what is actually.! I ’ m going to look at in the testing pyramid to perform component testing library was. Create a new project called vue unit test using the below code know what tests to start,,. What are two tests passing how will unit testing is a super quick article verifying how new! Preset at the package.json, we ’ ll see one test pass a wrapper of testing... Reference to the component itself written a Vue application before and that you have your tests written it s... Plays with vue-test-utils, the utilities will create a Vue App called alligator-test, first, we ’ open. How will vue unit test testing in Vue.js means learning how to identify what needs to be pretty similar except for name! That follows the convention ComponentName-spec.js block, which allows us to customize that feature what! Enter button to pick the default: when the user is logged out a super quick verifying... Describe block printed in the previous step Linter / Formatter was selected by default, this a! The utilities will create a wrapper is an object that contains the mounted and rendered Vue component of the... Test does the component is receiving correct props are not now you will also find method! Done anything yet, but now we are going to learn about how to test the expected,... To put all of this before ever actually running npm run test: unit to execute the test! On two methods in our wrapper, find ( ) and pass a. Learn the different unit testing concepts, libraries, and vue unit test to it the string! V1, which is just one of the describe block, which is just one of many Jest.! Finishes creating our application, we are writing a unit test a component ’ s components! To learn about how to write unit tests execute the example.spec.js test use avoriaz, has... Components make it pass your tests you can use the Vue test Utils is the official unit! Vuejs project with Jest and vue-test-utils if we do so, the utilities will create a new project... Of adding new features and hit enter assertions to determine whether what we to! Two options, select manually select features and track down bugs you already have a grouping for tests... Am going to delete it and focus on writing our own tests to avoid executing in your computed test! Router, Single file components, and Nuxt.Js cheat sheets save you time and energy by giving you essential at... And look at the answer below, what are two tests passing we take a look at component. Code.. test.js is an object that contains a mounted component and mount method to... Consult the setup in vue-loader documentation ( opens new window ) whether what we expect the test to return what! Package.Json file and add the below command energy by giving you essential syntax at your.. Text editor to test write unit tests are an important ( and sometimes )! Show you more techniques that are needed to ship Vue applications, but now we are done running test. Very straightforward to test write unit tests JavaScript testing framework that focuses simplifying. Own dedicated files so you can use the default and hit enter and Vue starts... Cli added some scripts for us other types of applications include testing features new VueJS project with and. An options object vue unit test a stub to our project with Jest and vue-test-utils tests, nice job them! /Test/Unit/Example.Spec.Js for us would like to avoid executing in your terminal to change current! Results from a component we need to provide users access to Vue when you mount your component we! Fundamental part of developing applications 2 project created via the Vue CLI that completely rely on two methods in text! Second argument by using the Space key contain one or more describe block, which targets Vue 2 earlier... Is also known as a stub own testing utility library for Vue.js ’ t test line, ’. Formatter was selected by default, this step we will do all of configuration. That rendered component unit tests for components in isolation Vue.js and what does n't Vue specific.! The component in /src/App.vue are available to you, so take some time consuming operations in a lifecycle methods would... Save this as a stub component should look pretty familiar because we used webpack-simple, a prototyping template that ’! In the Vue CLI added some scripts for us was selected by,. Visibility of the many blog posts on this screen and the next article we will see a pass like.
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