Mocha test


  • Mocha.js, the JavaScript test framework: A tutorial
  • Why Mocha is our ‘5-star’ Javascript unit testing framework
  • Getting Started with Node.js and Mocha
  • Better patient care
  • Get Started Quickly and Easily Testing With Mocha and Chai
  • Mocha.js, the JavaScript test framework: A tutorial

    This article will walk you through its installation and configuration, as well as demonstrate its usage by implementing a color converter that can translate from RGB red, green, blue to hexadecimal color representation.

    In addition, we will create a web server that exposes the above converter and demonstrates how to test asynchronous code. Bootstrap We will start by creating an empty directory. During the server testing phase, we will need a way to send HTTP requests.

    Request is an excellent choice. However, we will configure one more thing to make running the test suite easier. We will set up the test command inside the package. The following command is used to invoke the Mocha binary installed locally in the. Next, we will update the test command in package. The first argument is a simple string that describes the feature, while the second argument is a function that represents the body of the description.

    The it function is very similar to the describe function, except that we can only put expectations in the body of the it function. In the body of our first it function, we will test the rgbToHex color converter. As its name says, it converts from a red, green, blue tuple to hexadecimal. We will test it by converting the basic colors. It is called a matcher, and it matches the result of a feature with an expected value. There are of course many other matchers defined in the Chai libary , that can match expectations by various criteria.

    Test failed. See above for more details. It takes three arguments and returns a string that represents the color in its hexadecimal representation. We will use the toString method of the incoming numbers, combined with the number 16, to invoke a conversion to hexadecimal representation. Notice that we have padded the resulting value with a zero prefix if it is only one character long because a valid hexadecimal representation must always contain two characters.

    To implement the function that converts from hexadecimal to RGB representation, we will use the parseInt function with the base 16 to convert parts of the incoming strings into valid decimal RGB values. To test the HTTP request, we will also require the request package.

    Before running the tests, we will run our web server on the localhost port To make a request, we will use the Request package. We need to pass two arguments to it: a URL to visit, and a function to be invoked when the request is completed.

    We will set up our expectations inside those callback functions. Nothing will fail, but, at the same time, no expectation will be checked. Fortunately, Mocha gives us a nice abstraction for this issue.

    For every it that needs to wait for a response value, we will inject a done callback function and call it only when our expectations were executed. This way, Mocha will know it needs to wait for some of the expectations. We will also include our previous color converter implementation:.

    The only thing left is to parse our incoming parameters, pass them to the converter, and send the results back to the client. Having everything in a central location allows for continuous testing. CI allows us to create a short feedback loop, we know immediately the exact point where an error has been introduced..

    Teams using CI can merge many times per day, shortening development cycles while improving on software quality. To get started, we need to push the code to GitHub. Sign up for a GitHub account. Pipelines are made of blocks that are executed from left to right in an agent. Agent: The agent is the virtual machine that powers the pipeline.

    We have three machine types to choose from. The machine runs an optimized Ubuntu Block: blocks group jobs that can be executed in parallel. Jobs in a block usually have similar commands and configurations. Once all jobs in a block complete, the next block begins. Job: jobs define the commands that do the work. They inherit their configuration from their parent block. We need to make a small change before we can run our pipeline.

    We have to ensure the application is running before we try the tests: Click on the Test block. Save the NodeJS dependencies in the cache. Semaphore has a complete toolbox with commands to help us manage the CI workflow: checkout: the checkout commands clones the correct revision of the GitHub repository and changes the directory.

    Cache smart enough to figure out which files have to be stored and retrieved. You have an optimized pipeline, a solid foundation for your NodeJS projects.

    Why Mocha is our ‘5-star’ Javascript unit testing framework

    Using automated testing allows you to sleep soundly at night as you know for sure your code works properly. A good Javascript testing framework may become your sleeping pill. A well-tested code means better architecture. It is always easier to modify and improve. Theoretically, it is possible to test an app without using automated testing tools, but in reality, it involves additional stresses like writing helper functions, command-line utilities, feeling anxious about how to run asynchronous tests and so on.

    Eventually, you will end up building your own custom test automation framework. No need to reinvent the wheel.

    JavaScript, like any other programming language, has a number of tools that allow test-driven development, like Jest , Jasmine , Mocha , QUnit , Karma , Cypress , and others. But choosing among JS testing frameworks turned out not to be an easy task. So, this article will be useful for those who face the same situation and are looking for a suitable testing tool to use.

    After comparing a good deal of Javascript unit testing tools, the choice fell to Mocha JS. In this article, I will explain the determinative reasons and whether we regret the choice now a little spoiler — no, and here is why. Mocha JS does both. It is a solid open-source testing framework used by JavaScript developers for unit testing. We like frameworks that are easy to use, open-source, flexible and have a great support community. Unlike Jasmine, for example, Mocha is used with third party assertions, mocking, and spying tools.

    It also provides a wide variety of features allowing to create descriptive auto-tests, reports and even running automated tests each time the file was changed locally. And the list could go on! During the working process, we have singled out the other benefits of the Mocha unit test framework. Reason 1. Today, there are many companies that opt for behavior-driven development in writing automated test cases, and those who use test-driven development. No matter what testing process you use, Mocha will work well for you.

    Reason 2. Has a number of installation options The developers can select a way to install and use Mocha JS depending on the project needs. For example, in the case of using it for NodeJS, you can opt for installing Mocha either locally or globally by means of specific commands.

    It is also possible to set up Mocha in the client-side and run unit test js directly in the web browser. Reason 3. Supports any assertion library Mocha, unlike other test frameworks, includes no built-in assertion library. An assertion library throws exceptions on failure. No assertion library out of the box may seem like a strength and weakness at the same time. Mocha requires more configuration and, therefore, may seem intimidating for beginners. On the other hand, this makes Mocha unit test coverage very flexible.

    Mocha software works with a number of JavaScript assertion libraries like Express. We opted for Chai Js. Mocha is a library that allows running tests, while Chai contains helpful functionality to verify test results.

    In fact, Chai can be paired with any Javascript unit testing framework. Using a combination of Mocha and Chai is a great option that provides living documentation for the specifications of the features of your products. Reason 4. Makes asynchronous testing easy A lot of Node. Mocha JS, in contrast to other JavaScript testing frameworks, makes it possible to test asynchronous code with a very similar syntax.

    Reason 5. Additionally, Mocha has many plugins and extensions to test unique scenarios. Reason 6. Allows the use of a variety of reporters and customization With Mocha, developers have a choice from multiple built-in test reporters.

    You can choose such reporters as dot matrix, nyan, tap, landing strip, list, progress, and JSON. Additionally, you have an opportunity to create your own customized one as well. The test reporters having full color allows checking execution and output. Reason 7. Is compatible with most web browsers Mocha has both a browser build and a node command line program so you have a choice again — test in client and server-side environments.

    As for the web browser, developers can run Mocha unit test on a number of widely used web browsers together with browser-specific methods and options. Along with the mentioned benefits, there are several drawbacks we have faced with Mocha. Among them is the fact that Mocha runs all the tests in the same process, which means shared memory and no independence or isolation.

    It may cause various conflicts. Mocha also is unable to run tests in random order. Nevertheless, we are quite satisfied with Chai Mocha union as it helps us to run automated testing easily and effectively.

    In particular, it: allows growing our applications with certainty that the code is always checked and working, allows to make changes fast and free from anxiety, helps to shorten the development cycle as there is no need to manually check all parts of an app before pushing to production, provides early detection of bugs and broken functions thus an ability to eliminate them in a blink of the eye it has already helped us more than once , and improves the growth and scalability of our products as code runs as expected.

    As for the projects, Mocha works especially well for large projects where flexibility and customization are a major asset. But even if you have a small or medium project that involves frequent changes and lots of logic, testing with Mocha is still a great aid too. From the start, it may seem that it takes a lot of time to write automated tests, but it is definitely worth it.

    We have tested it out and suggest you do the same no matter what testing tool you finally choose. And do not forget to subscribe to our blog to receive more insights and stories from our experience!

    Mocha software works with a number of JavaScript assertion libraries like Express. We opted for Chai Js. Mocha is a library that allows running tests, while Chai contains helpful functionality to verify test results. In fact, Chai can be paired with any Javascript unit testing framework. Using a combination of Mocha and Chai is a great option that provides living documentation for the specifications of the features of your products.

    Reason 4. Makes asynchronous testing easy A lot of Node. Mocha JS, in contrast to other JavaScript testing frameworks, makes it possible to test asynchronous code with a very similar syntax.

    Reason 5. Additionally, Mocha has many plugins and extensions to test unique scenarios. Reason 6. Allows the use of a variety of reporters and customization With Mocha, developers have a choice from multiple built-in test reporters.

    You can choose such reporters as dot matrix, nyan, tap, landing strip, list, progress, and JSON. Additionally, you have an opportunity to create your own customized one as well. The test reporters having full color allows checking execution and output. Reason 7. Is compatible with most web browsers Mocha has both a browser build and a node command line program so you have a choice again — test in client and server-side environments. As for the web browser, developers can run Mocha unit test on a number of widely used web browsers together with browser-specific methods and options.

    Along with the mentioned benefits, there are several drawbacks we have faced with Mocha. Among them is the fact that Mocha runs all the tests in the same process, which means shared memory and no independence or isolation. Using the Mocha. To start, you must implement a sum function that: Can accept any number of arguments Requires all arguments to be numbers and throws an error if any is not a number Computes and returns the sum of its arguments provided all are numbers Returns 0 if no argument is passed First, define the test suite with tests for the required functionalities.

    Create a new sum. Also notice that the sum call is wrapped in a function to test that an error is thrown when non-number arguments are passed.

    Getting Started with Node.js and Mocha

    This is a requirement of the. Next, go ahead and implement the functionality for the sum function as a module export, run the tests, and ensure that all the tests pass. However, most Node. You can use any of the following to test asynchronous code with Mocha.

    Callback function The function passed as second argument to it can be passed an optional callback function as its first argument.

    When this callback function is passed, Mocha. Conventionally, the callback function is named done, but you are at liberty to use any identifier you choose. Calling it multiple times will throw an error It is a Node-style callback, hence it can take an Error instance err as its first argument Calling the done callback with an Error instance causes the test to fail with the given error Before you proceed, here is a simple module that exports an asynchronous md5 function for computing the MD5 hash of a string.

    Create a new md5. Whenever you return a promise from the function passed to itMocha knows that the functionality to be tested is asynchronous, so it waits for the promise to be fulfilled before proceeding to the next test. From Mocha. However, in older versions of Mocha, the call is ignored.

    Better patient care

    To test asynchronous code that uses promises, you will create another version of the md5 module that is based on promises. Create a new promise-md5. The -f flag instructs Mocha. Here is what the output should look like: 3. The previous promise-md5. Hooks are basically logic that have been configured to run before or after tests. They are useful for setting up preconditions for tests or cleaning up resources after tests. With the default BDD interface, Mocha. The callback function contains logic to be executed when the hook is triggered.

    Get Started Quickly and Easily Testing With Mocha and Chai

    The logic can be either synchronous or asynchronous just as it is with regular test cases. However, if a named function is passed as an argument to a hook, the name of the function is used as a description if no explicit description was passed. The describe function is a way to group tests in Mocha.

    You can nest your tests in groups as deep as you deem necessary. Root-level hooks apply to all test files regardless of where they are defined. This is because Mocha implicitly creates a describe block, called the root suite. We will use the toString method of the incoming numbers, combined with the number 16, to invoke a conversion to hexadecimal representation. Notice that we have padded the resulting value with a zero prefix if it is only one character long because a valid hexadecimal representation must always contain two characters.

    To implement the function that converts from hexadecimal to RGB representation, we will use the parseInt function with the base 16 to convert parts of the incoming strings into valid decimal RGB values. To test the HTTP request, we will also require the request package. Before running the tests, we will run our web server on the localhost port To make a request, we will use the Request package. We need to pass two arguments to it: a URL to visit, and a function to be invoked when the request is completed.

    We will set up our expectations inside those callback functions. Nothing will fail, but, at the same time, no expectation will be checked. Fortunately, Mocha gives us a nice abstraction for this issue.

    For every it that needs to wait for a response value, we will inject a done callback function and call it only when our expectations were executed. This way, Mocha will know it needs to wait for some of the expectations. We will also include our previous color converter implementation:. The only thing left is to parse our incoming parameters, pass them to the converter, and send the results back to the client.

    Having everything in a central location allows for continuous testing. CI allows us to create a short feedback loop, we know immediately the exact point where an error has been introduced.

    Teams using CI can merge many times per day, shortening development cycles while improving on software quality.


    Mocha test