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Thursday, November 28, 2019

Cypress (yet another) Selenium WebDriver killer

There is no perfect tool, there are tools which satisfy specific requirements and Cypress is one such tool. I have not used Cypress and my assessment on this post is limited to information I have gathered reading about Cypress. Cypress appeared to me Selenium Remote Control (aka Selenium 1) repackaged with Chrome browser at it target. Cypress target audience is different than of Selenium's, let's see what requirements they cater to.

Cypress target audience seems to be front-end developer. Its power lies in being able to test front end without having real back end or a mocked backend. Selenium's power lies in its integration capability with various other tools and APIs. Imagine testing on staging system which requires java based API to be invoked to create customer account following which using WebDriver to login to frontend and creating a transaction following which data base assertion to verify transaction attributes. Not all of these operations can be carried out using selenium however Selenium's vast support of languages makes all of these operations possible in selenium bases test suite.

Cypress focus area is Chrome. Given that we are past IE7 era, running tests on Chrome (or FF or modern IE) means that most of the time having a feature work on one browser would most likely mean that it works on other browsers too. Selenium's Support of multi-browser has also resulted in Bane. In theory Selenium tests are written once and run on any browser in practice Selenium tests are written once and debugged on any browser. The question we need to ask ourselves is that do we really want to run tests on gazillion of browsers.

What Cypress does not get right. Automation tool should be non intrusive in nature that is it should not change state of application to be able to work with it. You want to test the same application what your customers use and not a modified version of it. Unlike Selenium which uses browser automation APIs to carryout operation on browser, Cypress injects a js file to be able to execute test code. This intrusive nature of tool goes against principles of software testing.

Cypress solves very specific problem set in area of test automation although these problems can also be addressed by Selenium. In the end it is up to us which tool set we want to use to cater our requirements.

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