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Does anybody have some words of wisdom / articles / tutorials / books on TDD for your typical web applications? I am asking because for me, writing tests befor

Does anybody have some words of wisdom / articles / tutorials / books on TDD for your typical web applications? I am asking because for me, writing tests before the code is a natural choice for pure functions where I can easily map inputs to outputs. I cannot imagine writing that kind of code without tests. But the usual task is gluing together tons of components and 3rd party calls (e.g. starting from an HTTP request, doing some transformations, calling some APIs maybe, persisting stuff in the database). All of this depends on tons of side effects and hard to mock components. The only test I can write there easily is a full contract that mapping the HTTP request to HTTP response. This doesn't help me with developing the internals (definitely not TDD), it only verifies the end result. Even worse if there is no clear response but the result is piped into some queue over the network or something similar. I am either completely incompetent or I develop applications that are tons of hard to test stuff (especially with simple unit tests) with only tiny core of functionality that seems easy to test.

dakom 7y ago
Here's a few ideas on testing web apps: 1. The internal pure data representation. If you're using some state management like redux or xstate then you can just cache the state on changes and run tests as-is (e.g. running the tests would be sending events and then checking that the state is what you expect it to be). 2. The page itself. Tools like Selenium and Cypress will allow you to easily inspect and run tests against the DOM state (e.g. running the tests would be emulating interactions with the page and checking that the properties of elements are what you expect them to be) 3. Checking the virtual dom (or other middleware). For example, with React, you can "get at" its internal data (at least the level you need) via a testing framework like Enzyme. 4. If your app uses webgl context or is simply too hard to test on any of the above "pure data" levels, you need some sort of image recognition to compare pixels. I doubt this is going to be _perfectly_ testable but you can try your hand at Sikuli or roll your own with OpenCV

dakom 7y ago

Here's a few ideas on testing web apps: 1. The internal pure data representation. If you're using some state management like redux or xstate then you can just cache the state on changes and run tests as-is (e.g. running the tests would be sending events and then checking that the state is what you expect it to be). 2. The page itself. Tools like Selenium and Cypress will allow you to easily inspect and run tests against the DOM state (e.g. running the tests would be emulating interactions with the page and checking that the properties of elements are what you expect them to be) 3. Checking the virtual dom (or other middleware). For example, with React, you can "get at" its internal data (at least the level you need) via a testing framework like Enzyme. 4. If your app uses webgl context or is simply too hard to test on any of the above "pure data" levels, you need some sort of image recognition to compare pixels. I doubt this is going to be _perfectly_ testable but you can try your hand at Sikuli or roll your own with OpenCV