Cypress vs Selenium: Key Differences
Why compare Cypress and Selenium?
In spite of Cypress being recently introduced, it has gained significant traction with 22k+ Github stars and 530k+ downloads on a weekly basis. With such significant growth in the adoption of Cypress, it’s natural for testers to compare the two before choosing the ideal tool for test automation.
So, the question is, how does Cypress compare to Selenium? Is Cypress a better alternative to Selenium?
An easy way to answer these questions is to evaluate the advantages and limitations of each tool by having an upfront comparison of Selenium vs Cypress
So let’s get started.
Cypress
Cypress is a purely JavaScript-based front end testing tool built for the modern web. It aims to address the pain points developers or QA engineers face while testing an application. Cypress is a more developer-friendly tool that uses a unique DOM manipulation technique and operates directly in the browser. Cypress also provides a unique interactive test runner in which it executes all commands.
The official documentation states that Cypress differs fundamentally and architecturally as compared to Selenium.
Using Cypress, QAs or developers can create:
- Unit tests
- Integration tests
- End to End tests
The fact that Cypress is purely based on JavaScript indicates how this tool is designed to meet the needs of front end developers in particular. Naturally, one needs to be proficient in JavaScript before getting started with Cypress testing.
Advantages of Cypress
- Cypress captures snapshots at the time of test execution. This allows QAs or developers to hover over a specific command in the Command Log to see exactly what happened at that particular step.
- One doesn’t need to add explicit or implicit wait commands in test scripts, unlike Selenium. Cypress waits automatically for commands and assertions.
- Developers or QAs can use Spies, Stubs, and Clocks to verify and control the behavior of server responses, functions, or timers.
Limitations of Cypress
- One cannot use Cypress to drive two browsers at the same time
- It doesn’t provide support for multi-tabs
- Cypress only supports JavaScript for creating test cases
- Cypress doesn’t provide support for browsers like Safari and IE at the moment.
Selenium
As mentioned earlier, Selenium is a popular test automation tool that automates web-browsers. This open-source tool has been a leading choice for testers for over a decade now.
Developers and QAs also have the flexibility to choose the programming language of their choice. Selenium developers have developed language bindings for multiple languages like Ruby, Python, Java, etc.
WebDriver uses the JSON wire protocol for executing test cases. At a high level, execution involves three main steps:
- Test commands are translated into a URL
- Browser Drivers receive these URLs using the HTTP server
- The URLs are forwarded as a request to the actual browsers, and all commands in the test scripts are executed.
Refer to this detailed explanation of Selenium WebDriver’s architecture for a better understanding of this operation.
Key Advantages of Selenium:
- Compatible with multiple OS like Windows, Linux, Unix, Mac
- Provides QAs the flexibility to select the programming language of their choice like Java, Ruby, Python, etc.
- Compatible with modern browsers like Safari, Chrome, Firefox, etc
Limitations of Selenium:
- No built-in command for automatic generation of test results
- Handling page load or element load is difficult
- Limited support for testing images
- Creating test cases is time-consuming
Although Selenium and Cypress are both designed to automate browsers for testing purposes, they differ considerably in terms of architecture and performance. A key difference is that Cypress as a tool is ideal for introducing developers to test automation rather than just a replacement for Selenium. This is why Cypress is among the fastest-growing automation tools in the world. On the other hand, Selenium is a more general-purpose tool targeted at a broader audience.
