23 Node.js Best Practices For Automation Testing

Posted by Rahul Jain | November 18, 2020
Automation โ€ข

31701 Views | 16 Min Read

Node JS best practices

If you are in the world of software development, you must be aware of Node.js. From Amazon to LinkedIn, a plethora of major websites use Node.js. Powered by JavaScript, Node.js can run on a server, and a majority of devs use it for enterprise applications. As they consider it a very respectable language due to the power it provides them to work with. And if you follow Node.js best practices, you can increase your application performance on a vast scale.

When it comes to automation testing, it requires a very systematic approach to automate test cases and set them up for seamless execution of any application. This requires us to follow a set of defined best practices for better results. To help you do that, we will let you in on the best Node.js tips for automation testing.

1. Small & Solitary Test Cases

For better test results, test cases in Node.js are usually kept small and to the point. As the best Node.js practices go, you will find each case and its test data being distinct from the other without any interference. This enables failures from one test not to impact other test failures and provide more concrete results. Also, it would help improve test performance to a great extent.

2. Test Case Nomenclature

A meaningful name means a lot in writing test cases. It’s crucial in writing effective test cases as the name should be able to communicate the case goal by being meaningful and easy to comprehend for all stakeholders. Never assign a test with any random name. You should name it as properly as possible like checkCountryLanguage() or validateUserPhoneNumber(). A good test case name should clearly state the following:

  • feature under test
  • the particular scenario being executed
  • the expected result of the test

3. Using BDD Style

Using a style that helps to write tests in a language that is close to product expectations is one of the universally accepted Node.js best practices. Such declarative writing style enables users to instantly understand the test flow and expectations in a single glance, keeping the actual coding parts hidden from non-technical stakeholders. BDD or Behavior Driven Development is the best example of such an approach and is very popular among organizations due to its ease and ability to integrate well with Node.js.

4. Implementing Assertions

Assertions make up a very important part of any test case. These declared statements may or may not be true and provide a Boolean output, which helps us to verify whether a test case is executed as per expectations or not. Assertions are very integral to Node.js automation testing and highly recommended to be used in a self-explanatory way, thus reducing code efforts and providing solid results. Assertions are useful as they save the devโ€™s time to check the complete output and respond on each step by comparing the expectations with results and letting us know if a test passed or failed. These assets are human-readable and easy to implement through Chai library support in a node.

One example of a good assert is : expect(todayWeather).to.be.(clear);

5. Minimal Test Case Helpers & Abstractions

A good test case code is well-factored and has minimal external interactions. It is a complete unit in itself and has the least utility, hooks, or external effects. It should be written so that a new developer or tester should not have to move to another test to understand the previous one or go through a complete hierarchy of test cases. Minimizing these makes the test less complicated, easy to understand, and easy to maintain and is considered an essential Node.js best practice.

6. Test Runners

Often referred to as a library or tool, a test runner runs tests on a source code directory, which contains many unit tests. It shares the test results run in the form of log files or console logs in a readable form for the user. There are various test runners present in the market, but the best-suited test runner for Node.js is Mocha. Mocha is an open source test runner that provides a programmatic easy-to-implement approach to test runs and gets good results. It is also beneficial while working with databases to feed values to test cases that can be dummy or real as required and handles the disadvantages of most other Node.js test runners.

7. Crisp Test Coverage

Test coverage is essential for any good software code. It is the measure of the amount of code covered by test cases and hence is considered a crucial point while writing tests. So as per Node.js best practices, while writing test cases for good coverage, always remember that-

  • It is very dependent on the nature of the software application.
  • Wise decisions should be made about what to add and what not to add in the test coverage as it might increase the cost. If it’s a real-time, highly interactive application, then try to have test coverage at 100% for better results.

For better test coverage, the Istanbul test coverage tool can be used, and it integrated well with Mocha as well.

8. Additional Test Coverage With Plugins

Plugins are beneficial in writing good unit tests as they help to analyze written tests for maximum code coverage and any failures or skipped tests for any reason. They help by sharing proper reports of passed, failed, and skipped tests, thus preventing false alarms indicating low test coverage due to skipped or unexecuted tests. Considering how easy it is to implement this one out of the other Node.js best practices, you can always start here.

9. Test Coverage Report Analysis

Mocha and Istanbul make a very good combination to generate useful test reports that can be analyzed for better results, checked for failures or issues, and used to fix them up. Developers often swear by such Node.js tips. And using Istanbul with Node.js automation is pivotal as it gives easy and straightforward reports for test coverage and gives a percentage of the coverage as well.

10. Tagging Test Cases

Different test cases are focused on different scenarios and different requirements. It is always good to classify them separately as per their use and segregated into different groups with even one test being part of multiple such groups. The best way to do so is tagging the test cases like smoke-test, IOtests, sanity, e2e-tests, etc. It is very helpful when we need to do a quick test run and donโ€™t need to trigger unwanted cases for the changes being done.

11. Mutation Testing

The type of testing in which we use some dummy or mock data to tweak the logic and behavior of the application to make certain scenarios fail to analyze an application or simulate some real-time cases is referred to as Mutation Testing. It is also referred to as โ€˜Planting a bugโ€™ to see how the developed logics react in unexpected conditions. This is an excellent practice while automating Node.js test cases as it enables developers to be more prepared for unwanted surprises and handle them before they become a burning issue. Stryker is the most popular library these days to serve this purpose; add it to your list of the best Node.js tips you have ever come across.

12. Non-Plagiarised Tests

Using a unique, non-plagiarised code is very important for the company. At times, we might copy some snippets from the internet to make the condition work without realizing that it might be licensed to another organization. This can lead to serious legal troubles due to copyright issues and is not considered one of the best Node.js practices. Thus checking for plagiarism makes up a very frequently followed practice while working with Node.js and can be done by installing the package: node.js npm plagiarism-checker.

Hereโ€™s a code snippet on how to install and use it in your code.

  • To install : npm i plagiarism-checker
  • In order to use this library, add the following-

    var a = require('plagiarism-checker');

    var b = new a();

    var config = b.getConfig();

  • Next, download the code for plagiarism checker from here and add it to the project after installing the following dependencies-

    $ npm install lodash

    $ npm install request

    $ npm install request-promise

    $ npm install mime-types

13. Providing Logical Inputs

It’s always advised to use realistic and pragmatic inputs for the automated test cases that are close to real life scenarios and might occur in actual usage of the applications. At times, testers tend to use random values as inputs that are nowhere close to the actual scenario, and thus exact performance cannot be evaluated. We are always living in a false assumption of the application working fine. One such library that goes well with Node.js and generates such real-time inputs is Faker Library. It provides a large set of such data that you can use for better results.

Another one of Node.js tips to keep in mind is not getting content with a few inputs only as in real life; the application would be having a huge number of inputs. They are usually different in nature, yet they get processed by the same logic and function. So as per Node.js best practices, test them with a large and varied data set as available.

For example, for a function that takes city names as an input parameter, valid test data would be like New Delhi, Mumbai, London, New York, etc., and not some values like abc, xyz.

14. Using Lint

A tool used to investigate the whole code and raise red flags for any programming errors or bugs, code styling issues, or any suspicious constructs is referred to as a Linter or Lint in general. It’s a highly recommended practice while working with Node.js to use linters to catch the structural bugs in the code that are otherwise not visible on the logical side. These types of bugs include assignments of undeclared variables or the use of undefined variables or syntactical formatting errors. Fixing all these make the code look good and easy to read and understand. ESLint is one such tool that can be integrated with Node.js and used to follow such Node.js tips for automation.

15. Property Based Testing

This type of testing is used to check the various properties of a function or program in particular. It is dependent on different properties of the function under test. The property makes up a characteristic of the function or program. Some tools used in automating property based testing are fastCheck, Mocha Test Check, or QuickCheck.

It is a beneficial practice as-

  • Scopes for all the types of inputs and thus helps to generate a huge valid set of test data and test cases.
  • It helps to check the threshold value of a function by running it for a big-time with the required property type input.

An example of property based testing is a function that can take two arguments, and one of them is characterized to have input as even value only. Using property based testing, we can check behavior when that input is even and when it is odd.

16. Asserting With Chai

Asserts are a crucial part of automated testing. These assertions help compare the actual results with expected results and tell us whether a test case is behaving as expected or not due to some unintended bug or a known logical flow change. While automating tests with Node.js, the chai library is very useful for this task. It works by expecting the assertions and analyzing results to raise errors that are to the point. It leaves no more effort to dig in for the reasons, thus saving a lot of time and effort that can be used to deliver the fix. One example of chai assert can be


17. Testing The Exceptions

Testing the exceptions and being ready for them is an excellent practice while automating test cases. Generally, while writing tests, we focus on test cases and scenarios that provide good code coverage but often ignore adding exceptions to be verified in these cases. When such exceptions occur, they might lead to unexpected behavior or outcome for the application that can be fatal for the organization. Many big organizations have been doing this in their own way, and some refer to it as Chaos Testing. This is something that an unexpected exception would lead to if we are not prepared. Few examples for these Node.js best practices would be-

  • Systematically killing the servers and testing all the functionalities in such scenarios to gauge the stability, performance, and impacts on application.
  • Another way can be to forcefully pass different response codes from the server side and check how the application behaves.

18. The Testing Pyramid

One of the most followed Node.js best practices while writing test cases with Node.js is following the Testing Pyramid. A testing pyramid is a triangle divided into three parts. Each one defines three different test stages/approaches and classifies them in terms of cost incurred and speed of execution, with the peak signifying the most expensive but fastest testing.

At the bottom of this pyramid are the tests covering independent basic functionalities or the unit tests. Integration tests make the middle layer of this pyramid. This lets users test different modules in integration with one another, which we have tested individually on the first layer. Next and the last one making up the peak is front-end or user-interface testing, which can be done with various advanced automation tools like LambdaTest. These unit tests are the slowest due to large numbers of such tests, while front-end ones are the quickest due to lesser module level distribution.

19. Testing Each Application Component Separately

This approach helps test the functionality of each module/component in isolation, and so is referred to as Component testing. In this, the response of the module under test is verified based on different inputs. Component testing is very useful due to its excellent coverage and better speed as compared to unit testing. In the testing pyramid, this is recommended to be used after unit testing for better results and finding more unknown issues.

20. Preparedness For Infrastructural Issues

Not giving a thought to the possible infrastructure issues and not testing them is one of the most common mistakes that testers make while automating test cases. The main reason leading to this is the thinking approach that, with the above mentioned Node.js best practices, we need to test only the application’s functionality and have good test coverage. This makes them ignore the more real time issues that might occur due to infra failures because of real time load and more practical scenarios.

Common infrastructure issues that are ignored and proven expensive for the company can be memory overloading, server breakdown, sudden shutdown of some server, or increased API response time. Let alone how these would impact the behavior of the application. Hence, including Infrastructure testing around these issues is a must to follow practice for better feedback and efficient resources management.

21. Parallel Testing

Oh, how tedious it can be to execute one case, wait for its result, analyze it, provide feedback, run the next test, perform the same process, and so on for all the cases! This also means the dev team will get feedback one by one for all test runs and will be able to resolve them one by one. This would increase the effort and time consumed and might lead to unnecessary rework as well.

Now think about an approach in which you can execute multiple cases simultaneously and get reports to be analyzed at one go, and share consolidated feedback to be worked upon. This process is called Parallel testing. It drastically lessens the feedback loop as many tests are executed together and hence can be resolved together as well in a shorter time. Thus saving a lot of time and resources for the company. The most popular library available to achieve this in Node.js automation testing is Mocha.

22. Keeping The Dependencies Updated

Effectively running tests for better results requires many libraries and tools to work in a synchronized, updated manner to provide the best results. But this requires a lot of manual effort to keep all of these dependencies and libraries updated to the latest version to prevent any unknown failures. This demands money and resources, yet the fear of execution on outdated versions remains due to the possibility of human error. This can be resolved by practicing automated updates of all the dependencies regularly. This can be achieved by adding some utility that regularly checks for the latest version updates and triggers an update if any release is found for any dependency.

23. Cross Browser Testing On Selenium Grid

For web based testing, everyone favors Selenium unanimously. It is an open-source easy-to-use cross browser testing tool that comes with many utilities and supports to fulfill all the requirements. The problem arises when we set up a Selenium Grid and want to remove the limitation on the number of browsers. In such cases, it is best to use a Selenium Grid cloud provider as it opens the field to have more browsers and with even more varied configurations.

LambdaTest is one such example of cloud-based cross browser testing. It offers an online Selenium Grid with 2000+ browsers and versions for different operating systems. You can automate the Node.js test cases, execute them in parallel, and view all the related logs and reports on the interactive LambdaTest dashboard.


Working with Node.js might appear a little challenging and frightening at the first look. But once you get past that initial stage, implementing Node.js is going to be the best thing you have ever done. With these best Node.js practices for automation testing, you can get the confidence to work with Node.js and develop a liking for it. These practices would enable you to create a stable and effective automation testing framework covering all required aspects and leaving no concerns to be addressed. So get started and enjoy automating with Node.js.
Happy testing!

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