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11 Best Practices for Node.js Automated Testing

by Albert Smith

The famous JavaScript environment Node.js is known for its resourcefulness and powerful development tools. It is used by a number of major websites including LinkedIn and Microsoft and is extensively used by developers for both client-side and server-side web development.

But no matter how adept a programming language or platform is, and how good the programmer is, every application must be tested to ensure its bug-free functioning. This applies to Node.js apps too, but Node.js automated testing demands a systematic and well-calibrated approach.

A developer needs to adhere to the standard coding practices to get a robust, error-free application because testing complex Node.js apps is a tad bit tougher as they contain several features and components. This article strives to make things easier with a briefing on the eleven best coding practices for testing Node.js applications.

Check out Here 11 Best Practices for Node.js Automated Testing

1. Testing with Realistic Inputs

Testers need to keep in mind that the test cases are for apps that have been written for real users who will use them for handling practical tasks. So instead of using random inputs, automated test cases should be carried out with logical and realistic inputs. The logical inputs will give a clearer idea of the app’s performance.

Testers can use Faker Library, a library that works well with Node.js, and use its extensive set of data to get more pragmatic results. Also, testers shouldn’t become content with just a handful of inputs since the real application would be getting a large number of inputs.

For instance, while testing a module that requires food names as inputs, the input given should be actual dishes like pasta, pizza, salad, etc. and not random variables like alphabets or a combination of alphabets.

2. Using Plug-ins for Maximum Test Coverage

While testing large applications, it might be possible that some part of the code might get skipped by the tester. Plug-ins can come in useful in providing maximum test coverage along with proper test analysis. This helps developers find out untested portions of source codes.

Jest is one such plug-in that supplies developers with productive testing tools and also performs isolated and parallelized testing for enhanced performance.

3. Using Linters

Linters are static code analysis tools that are used for source code analysis and detection of programming errors, formatting errors, styling issues, and structural bugs. A linter is valuable for developers as it helps them save time and resources by raising flags for any errors so that they immediately come to notice.

Using linters while working with Node.js is a common coding practice, and ESLint is the most commonly used linter for Node.js. Some of its explicit benefits are:

  • Automatic fixing of some errors (because of syntax-aware fixes)
  • Facility to write one’s own rules
  • Customization of parameters
  • Custom parsers

4. Nomenclature of Test Cases

Proper nomenclature is one of the most important things to do while writing test cases. Meaningful names not only help testers to understand the function that the code is performing but also make it easier for other departments to correlate with it. For example, if the test case is to check the calling function of an app, then the test case can be named as:

//code to check if the app can access contacts and perform calling

In case this function comes up with an error, then the development team will immediately know which part of the source code they should rectify. Otherwise, they will have to recheck the entire code. Testers should also follow nomenclature practices for different testing circumstances and their expected outcomes.

5. Implementation of Assertions

Assertions are vital to automated testing because they provide insights into whether the test cases were executed successfully or not. Assertions are Boolean expressions that stay true unless the program encounters a bug.

The implementation of assertions is a crucial step in Node.js automated testing as they are extremely useful in catching subtle errors that may otherwise go unnoticed. When an assertion step fails, the tests are aborted and further tests aren’t carried out until rectification.

6. Using Isolated and Small Test Cases

Test cases in Node.js should be executed independently from each other. Isolated and small test cases are more effective as the outcome of one does not affect the others. This practice also brings precision and makes it possible for developers to rectify errors without changing any other part of the app’s code.

Keeping the test cases small also ensures the smooth testing of large applications. Another good testing practice is to keep the testing data specific and separate for each test case as that result in more concrete results.

7. Updating the Dependencies

Automated testing often involves several libraries and tools and for accurate test results, it is imperative that all of them work in perfect coordination. An important step that is often mentioned for effective testing is to keep the testing platforms and their dependencies up to date as outdated versions can often return faulty outcomes.

Manually updating these dependencies can be tedious and time-taking as well. Automatically updating the dependencies is a viable option and for this, developers might need to add utilities that check for updates and trigger them whenever an update is found for any testing tool.

8. Checking for Plagiarisms

To ease the workload and to make development quicker, developers often make the mistake of copying code snippets from other similar apps and integrating those into their own applications. What they don’t realize is that they could get into serious legal trouble, especially if the software is copyrighted.

So checking for plagiarism is a necessary Node.js coding practice. One can install the package node.js npm plagiarism-checker to check for plagiarism codes in Node.js apps.

9. Using Test Runners

Test runners are testing tools that run tests by simulating virtual users through defined circumstances. The primary functions of a test runner are to collect the tests, run those tests and provide reports on test results.

A test runner usually consists of several unit tests and the results of the executed tests are presented in the form of either console logs or log files. Though there are many test runners available for Node.js, Mocha is the most favorable test runner. It is easy to use, flexible, open-source and gives accurate reports.

10. Analyzing Report of Test Coverage

A thorough analysis of test coverage reports can help a lot in minimizing the errors and functional flaws of an application. An experienced and dedicated Node.js developer would combine Istanbul and Mocha as it will produce useful reports that can be analyzed for finding issues and fixing those.

Jest and c8 also provide integrated support for Istanbul APIs that can assist developers in generating straightforward test coverage reports for Node.js.

11. Testing for Infrastructure Issues

Software systems are the main constituents of any application, but the functioning of an app depends on other infrastructural factors. Testers often tend to overlook the real-time infrastructure issues related to apps.

But an experienced tester, apart from following the standard coding practices for Node.js testing, will always carry out tests for finding common infrastructural issues like server breakdown, response time for enhanced APIs, memory overloading and sudden server shutdown.

Infrastructural testing has become a must as it helps in getting better and pragmatic feedback and also helps with resource management.


While Node.js is known among developers for its proven expertise, it is imperative for testers to stick to the standard practices for carrying out automation testing for Node.js apps. The practices mentioned here shall assist Node.js developers in creating more stable, reliable and flawless Node.js applications.

Frequently Asked Questions

Q – 1. What are some other popular test runners for running automated Node.JS tests?

Ans:- Apart from Mocha, other popular test runners which are good for Node.JS automated testing are Chai, AVA, and Test Double. One can use Jest too.

Q – 2. What is the benefit of unit testing in Node.JS automated testing?

Ans:- Unit testing works great when developers want to catch regressions in the codebase, i.e., when they wish to see whether changes in one part of the codebase affect the app’s other parts.

Q – 3. On what basis should I select the testing tool for Node.JS?

Ans:- The selection of the appropriate tool should be based on the testing requirements and the tool’s ability to cater to those. But some crucial features to look for are:

  • Testing abilities for objects and images
  • Debugging facilities
  • Database testing
  • Support for the testing environment

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