How to Run Cypress Tests in Parallel
By Ganesh Hegde, Community Contributor - January 5, 2023
Before diving into how to run parallel tests or how to run a test multiple times in Cypress, let’s get a quick overview of parallel testing in general.
What is Parallel Testing?
Parallel Testing is a commonly used term in the automation testing domain. Instead of running tests one by one in sequence, parallel testing allows for running multiple tests simultaneously. This approach executes tests on multiple browsers, devices, and operating systems parallelly.
Advantages of Parallel Testing
- Faster Execution: Executes tests in different instances machines simultaneously, reducing execution time and returning test results much quicker.
- Less Effort: When parallel testing is triggered, testers do not have to manually wait for one test to complete and trigger another test on a different browser. Tests run on multiple browser-device-OS combinations, so capturing results with less effort is easy.
- Better Test Coverage: Parallel testing allows for running tests on as many device-browser-OS combinations as the tester’s infrastructure and budget will allow. This will help attain maximum test coverage without significantly increasing execution time or compromising the accuracy of results.
Learn More: Accelerate CI/CD pipelines with Parallel Testing
Challenges of Parallel Testing
The major challenge in parallel testing is setting up infrastructure to execute said tests. Running multiple browser instances on a single machine can eventually overload the machine, eventually returning false failure results.
Accessing different combinations of real browsers, devices (especially mobile), and operating systems would also be a challenge, especially for teams that don’t have an in-house device lab (consistently maintained and updated).
Of course, it gets easier for QAs to perform parallel tests using a cloud-based testing platform such as BrowserStack. Testers can access a real device cloud of 3000+ real browsers and devices. It empowers teams to run concurrent Selenium, Appium, or Cypress group tests online on desired real device-browser combinations. Without the limitations of emulators and simulators, testers can verify website functionality in real user conditions.
Best Practices for Parallel Testing
- Keep Tests Independent: Create tests that are as independent as possible. Dependencies are major road blockers for parallel tests and increase failure rates.
- Focus on Test Data Management: Ensure that data values are refreshed inside test cases. If one test case alters the values of other test cases, that will eventually impact test results.
- Ensure Testing is carried out on Real Browsers and Devices: There is always the possibility that emulators and simulators will provide false results, so it is always best to test on real browsers and devices.
- Test Infrastructure: When testers run multiple combinations of tests parallelly, a certain load will be generated on the machine, depending on the number and nature of parallel tests. The test infrastructure should be designed to handle the load and execute test cases smoothly.
- Execute Tests on CI/CD pipelines: To yield the best possible output, create the infra for running parallel tests on CI/CD or opt for a ready-made solution like BrowserStack, which offers in-built CI/CD integration to run parallel tests.
With the best practices covered, let’s move on to parallel testing in Cypress.
How to run Cypress Tests in Parallel
Cypress restricts running tests parallelly on a local machine. The framework was explicitly designed to do this, and multiple reasons for this can be found in the Cypress official docs. It provides a Parallel Testing option by setting up multiple machines.
- To get started with Cypress group tests, one has to set up a parallel testing strategy per the needs of a particular project.
- This process can be complicated and time-consuming depending on the project and personnel.
- Another major challenge is maintaining the test infrastructure unless one utilizes a test-ready environment like BrowserStack.
The following section will demonstrate parallel testing in Cypress via the BrowserStack cloud.
Running Cypress Tests on BrowserStack
Since Cypress supports parallel testing only in multiple virtual machine instances, you need to set up the whole environment and make Cypress execute your tests. If you’re wondering how to run a test multiple times in Cypress, cloud-based platform testing solutions are best since they have already set up the environment. Real browsers and devices are ready and waiting on the cloud; you need to create test scripts and trigger the tests.
BrowserStack allows you to run Cypress tests on the latest browsers. Get 30+ versions across Windows and macOS, with more to come. You can also run hundreds of Cypress group tests in parallel without maintaining countless Docker images. It takes a few easy steps to start running Cypress tests on BrowserStack.
Step-by-Step Guide to Execute Cypress Tests Parallelly on BrowserStack
- Install Browserstack CLI
Follow the steps mentioned in this BrowserStack Documentation to Integrate Cypress Tests with BrowserStack
- BrowserStack provides two options to run Cypress Tests parallelly
1. Using browserstack.json file
2. Using CLI Mode
Check out the Official Documentation to learn how to Run Cypress Tests in Parallel using BrowserStack.
Leverage the various advantages of Cypress to run parallel tests effortlessly. Use BrowserStack’s real browsers to ensure that all tests return 100% accurate results, even when executing multiple tests simultaneously. Don’t limit your Cypress group tests to the various inadequacies of emulators and simulators; only rely on the real deal to create customer-ready, meticulously optimized web applications.