How to test your reactjs and nextjs frontend application built with NestJS backend and Graphql api

You should read this article if you’re looking to test your ReactJS or NextJS application built on the NestJS backend or GraphQL API

You’re probably a few steps in already, or just starting a new project with a better portion of your focus on flexibility and development wrapped around ReactJS, or the built on NextJS features.

Keep reading till the end of this article and you’ll pick out good helpful tips

What is React JS and how do you test it?

React is a JavaScript library for developing applications and site UI. Developed by Facebook ; now Meta. Maintained by a very stable community of developers, it’s features are tailored especially to handle single page apps for Web pages and Mobile interface.

Upon creation of ReactJS, REST API has been preferred for the fetching and storage of server information. Over time, GraphQL has become a much more enhanced competitor for the REST API, gaining more efficiency and less run time.

Applications built with ReactJS boast Speed and dynamic optimization. A reason for this is because it is a front-end framework, as well as Jest, its default testing library.

However, when using package-runner tools like create-react-app, one important SEO activity will be lacking in the source code because the content of your page will be displayed in root div and projected through JavaScript. Using NextJS in this case is ideal as SEO crawlers don’t pick it up anything otherwise. 

While there are a lot of ways to test React, the key takes on testing React and Next will be summarized in the following paragraphs.

By the end of this article, there are links to where can be further enlightened by an array of articles, enough to elevate your skill set value beyond the average test run developer.

How do we test React 

More often, a developer is met with the dilemma of not knowing what exactly to test.

 -How do I know what to test for?- 

Knowing that a single mistype could ruin a whole block of code doesn’t help either. Every unit of the code will need to pass an automated testing as a part of the whole.

Usually, a developer will receive a “Legacy code” which is to say the default code that comes without tests and they need to be tested freshly. Other times it is the developer who has to pull one out from his sleeves.

For any of the scenarios, you should consider building suitable test cases to check that all the input functions trigger the defined output, and make sure these functions happen

Various methods of Testing

The primary library tools for testing React include

React Testing Library, Jest, Enzyme, Cypress.io, Puppeteer, among a host of others

Which Testing Library is Best?

Differences in the various methods and tools of testing can influence choice of use, and also what you are looking for.

Enzyme by Airbnb is less of a framework and more of a utility kit for React testing with focus on working of the inner components and what shows to the end user. It gives the testing team a good simulation and rendering advantage on the component trees. For component mounting, Shallow and Mount are the primary functions.

Jest is another popular JavaScript library, for unit test creation and running tests mainly adopted by default on React builds. Developed by Meta as well, the kit works perfectly with ReactJS on default.

With Jest, developers have the liberty to conjure test functions with nearly no configuration. There’s also the “Snapshot testing” that is used in verifying the result rendering component. 

The component tree to be checked is captured by screenshot and analyzed in comparison to the standard that is passed as the minimum requirement.

Using Jest for code coverage.

When using Jest for code coverage, it is as straightforward as adding a flag. This prompts the library to pull code coverage data from any application.

When using Jest, you can cover more ground faster by employing a few tricks to the setup.

  1. Testing with a wider covering code is better in any case. You always want to test as many details as possible, no matter how redundant or unnecessary as part of its complexity.
  1. After running a couple of unit testing projects on the unit, it is better to report the highest one. In this case, functional coverage is reported and not the branch coverage. Removing untested code data from the report thesis is also done by default.
  1. Another tip to have better coverage is to break down /decompose the unit tests in the right way. One way is to split an already tested function into units for more coverage -as much as possible. Another way is by looking for untested functions and then inserting their votes into tested ones.

What is GraphQL

For the longest, developers have preferred GraphQL as a better option to REST API, though not without its shortcomings.

GraphQL is a query language in contrast to RESTs architectural approach to software engineering. GraphQL is simply an order of specific tools that function to a common command using a single channel.

Unlike with REST where the page data is loaded by running multiple URLs, GraphQL runs through all the required content in just one request. 

For a few years now, REST has been the preferred choice for creating API, and when flexibility is needed in delivery and performance there’s GraphQL.

Besides evolving areas like the time it takes to run queries, another difference between GraphQL and REST is in the graph data arrangement.

Testing GraphQL

Automation testing on GraphQL can be performed by a still multiplying number of tools and materials depending on what platform, language and test setup/ how the test will be run.

One of the most popular Testing kits here should be EasyGraphQL, as gathered from an average preference of JS developers. By synchronizing with some libraries, it gets easier to test and verify API feedback as part of a unit test suite.

Next JS, why do we use it?

Essentially, Next is a framework built on React to make the work of adding external links and routers to the application building blocks easier.

Next is built on React but with a few key differences. One of which is that SEO crawlers pick up the full page information on a Next generated source code.

React JS takes care of assembling components that the end-user sees. Next JS puts this to run with other libraries as a full web app with access to multiple functions. Some of which include /router; for navigation and easy routing through the app, /link; to allow external Web pages to be linked and open on command.

Nest JS; what is it used for?

Currently, NestJS is still arguably the fastest growing Node JS framework used for building scalable, more efficient server side systems  that are fit to undergo unit tests.

Using the same building blocks as Angular and React, it gives room for developers to work with some of the popular dev op modules, primarily nest-specific and with a very detailed documentation Containing examples, code sources, etc.

It improves the ease of integrating popular concepts like GraphQL, Caching, Validation, etc. and provides applications that can easily carry out automation tests.

Built with TypeScript, the framework is flexible enough to be used interactively with other libraries. This gives a great deal of freedom to the developer especially on the integration of external modules.

Nest JS testing

As previously mentioned, it is more advisable to have more unit tests and less of the more complex whole, just enough not to miss out on any one. A larger allocation of the time should also be dedicated to the much more valued tests that deal with functions that retain users. 

Quality outweighs quantity in this case, keep it simple. Avoid writing codes that will be impossible for you to maintain and probably need modification after implementation.

Another hack to help with simplicity is the use of Typescript, which is not exactly used in the automation testing process but it can come in handy when writing codes and converting them from static to Javascript. The process may seem like it needs a lot of time but eventually comes to play in keeping the code full.

Conclusion

In conclusion Using GraphQL over REST  involves a bit of learning to put you at an advantage, this may seem tedious but all worth it as automations in data retrieval are more specific to the necessary data which saves time and increases efficiency.

Writing tests for ReactJS and NextJS improves general outlook and quality of maintenance, creating better APIs by keeping the developer keen on the experience of delivering finer integration details.

Jest Code coverage is of high importance because untested functions will be brought to light, and the overall health of the project is further ensured. The aim is to cover as many lines as possible with a testing limit or threshold

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