A Guide to Snapshot Testing with Jest: Benefits and Best Practices

Jest Snapshot Testing - A Guide

In recent years, the application development industry has revolutionized a lot. Some of the common factors that have played a critical role in this revolution include integrating automation testing practices. While using automation testing, app developers can utilize various advanced testing practices to improve the quality of the application test bench and the individual application. Snapshot testing is an important part of automation testing that helps verify the proper placement and functionality of the user interface elements present in a web application. With Jest, app developers can easily execute snapshot testing on their applications. However, there are certain parameters that the app developers must be aware of to utilize the full potential of this process properly.

So, with this article, we are going to guide the new app developers and testers toward the setup process for snapshot testing. We’ll also understand some of the major benefits and practices that can massively influence the outcome of this process. Our discussion will also include the role of multiple platforms and tools in the efficiency of Jest snapshot testing.

Understanding The Market of Jest Automation Testing

Currently, application developers are utilizing the potential of automation testing to eliminate the involvement of human testers in the application testing lifecycle. This is because, with this advanced process, the system can emulate human interactions based on a text file that will supply all the required data, parameters, and statistics. Using these interactions and communications, the computer will generate A detailed report showing the stability and usability of the app. Then, the developers and testers can analyze this report to decide whether the application is fit to be released to the end users.

The testers and developers also have complete liberty of making significant changes in the test file to customize the parameters according to the project’s requirements. It is also very easy to store and reuse a significant portion of the existing test data in future app projects. However, automation testing is a long-term investment and requires a significant initial expense. This will cover all the charges for integrating various tools, plugins, and libraries for the proper execution of the test bench. Thus, companies must have enough resources to justify this transition.

Jest is a JavaScript automation testing framework designed on top of Jasmine, and it is currently maintained by Meta, which was previously known as Facebook. The primary motive of Jest is to simplify the automation testing of modern web applications. With the help of Jest, application developers can verify the proper functioning of thousands of elements that are present in modern web apps. This is also useful for verifying the performance of applications that are based on React and TypeScript. Many application developers often consider Jest to be a comprehensive JavaScript testing solution due to its native support of this popular programming language.

Elaborating Snapshot Testing

Snapshot testing is the process of comparative analysis of a website’s user interface. In this process, the application developers have to capture a snapshot of the existing user interface. After this, they can implement all the required changes in the UI. The final step in this process is to use the snapshot as a parameter to compare the changes in the application UI. This will provide vital details like the misplacement of web elements, missing interactive boxes, and many others. There are various automation testing frameworks like Jest that provide native support to Snapshot testing.

With the help of Snapshot testing, the application developers can also verify the app’s compatibility on multiple devices like desktops, smartphones, and even tablets. Snapshot testing is also useful when the application developers are trying to increase the compatibility of an app with the older versions of a browser. It is a very important parameter as various market studies show that a huge segment of the user base does not update their browsers.

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Benefits and Best Practices of Jest Snapshot Testing

Benefits:

Application developers and testers need to be aware of the benefits of implementing Jest snapshot testing. This is because, with the help of this knowledge, app developers can not only customize the test cases but also utilize the full potential of the test bench. Some of the major benefits of this integration are as follows:

Integrating Jest with snapshot testing allows the application developers to simplify the test case creation process. This is because while using this framework, the application developers do not have to create assumptions for all individual test cases. Instead, the testing environment can automatically predict the expected output for any given test case. Therefore, this process also plays a critical role in saving time during the test case execution process.
Snapshot acts as a barrier that can help the application developers to prevent any unintended changes. This is because, during the comparison process, the system can automatically detect any missing changes from the captured snapshot. So, the app developers can easily detect and remove critical bugs and errors present in the core framework of the application.
The snapshot test cases are highly easy to maintain. This is because the data source is external and not integrated with the test code. So, the app developers can reuse the test cases without making any significant changes to them.
Snapshot acts as a self-documentation that provides all the required information regarding the test code and its target elements. Therefore, it plays a critical role in understanding complex applications that consist of thousands of different elements. We also suggest the app developers properly name the snapshot test cases according to the target elements in the process.
The use of snapshot testing can massively boost the collaboration among different teams present in a web development company. This is because the process of capturing snapshots can simplify application compatibility while working in a shared environment. It can also verify the compatibility of multiple configurations and testing environments.

Best Practices:

To realize the full potential of Jest snapshot testing, the app developers have to implement various best practices. Based on our research and understanding, some of the most beneficial ones are as follows:

The application developers can integrate cloud-based solutions with their Jest snapshot test cases to improve the accuracy of the test cases. This is because, with the help of cloud platforms, the application developers can execute these test cases on various real devices present on remote servers. So, it improves the accuracy of the test cases, removes geolocation barriers, and helps access legacy devices that are no longer physically available in the market. Cloud platforms also help save the hassle and expense of contemporary onset device test labs. We can learn more about the contribution of cloud-based solutions in the modern app market with LambdaTest as our benchmark:

For a basic understanding, we can say that it is a modern automated digital experience testing platform for web apps. LambdaTest can execute the automation test cases from various Test suits and frameworks like Cypress, Selenium, and Playwright. This platform is also suitable for verifying the performance of Web apps with local host servers. LambdaTest uses parallel test execution to improve the efficiency of the test cases multiple times. This platform supports the execution of automation test scripts from Selenium on more than 3000+ environments, including real devices.

The application developers should be mindful of over-snapshotting. This is the term that is used to refer to when the app developers and testers capture snapshots of certain parameters that do not need to be snapshotted. These parameters are those with elements that are prone to frequent changes, like dynamic containers for data.

On the other hand, under snapshotting is the process when the app developers fail to properly capture all the elements that are required to maintain a fixed position in the user interface of the application. So, we recommend the app developers and testers create an elaborate test plan that will help them to track all the elements that need to be covered in this testing process. While devising the test plan, it is very important to not only include the testing and development teams but also the business and production teams. This practice helps to create a basic awareness of the current status of the app development project.
Application developers need to integrate snapshot testing with the other test cases that are present in a web application. So, we would recommend the app developers consider snapshot testing as an additional tool and not as a replacement for critical test cases like unit testing and integration testing. The combination of multiple test cases is one of the most important practices that can help to guarantee the proper execution and functioning of modern applications comprehensively.
While performing snapshot testing of user interface elements, the application developers can use Jest’s ‘toMatchSnapshot’ with the ‘toMatchInLineSnapshot’ modifier. Using this method, the application developers can declare the snapshot within the test case. The major benefit of this process is that it makes the snapshot cases more readable and also reduces the clutter in test cases.

The application developers need to declare snapshots in the version control of the web application. This is a parameter that can help improve the consistency of the test cases and also make snapshots a part of the code review process. The visual representation of various parameters makes it easy to understand for different teams of a company that might lack the required technical knowledge.
Finally, we would recommend the app developers go through the official documentation of Jest. It will provide various features that can massively contribute towards a customized testing process depending on the requirements of the application undergoing the development process.

The Conclusion

In this article, we discussed some of the best practices and benefits that application developers must consider for the introduction of Jest snapshot testing. In this era of rapidly revolutionizing technology, it is essential to constantly update oneself regarding all the new additions and trends in this segment. This is also an important parameter that massively boosts the development and testing capabilities of a company. So, app developers can consider it to be a golden opportunity for maintaining a positive image of their brand in the segment. Frequently collecting information regarding the target audience’s requirements can also help in this transition. The app companies can conduct seminars and campaigns to boost the knowledge of their teams.