For very simple test cases of simple methods/functions it's ok. Once code starts to complicate, you'll lose much more time trying to steer the LLM into writing what you need, than simply doing it yourself. In particular setting up and creating mocks seems where the most difficulty lies.
Once you create the test, you can use the LLM as a code completion tool, to test for more things once you get a complex result. Or you can ask it to extrapolate from test data to create more test cases.
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I used just ChatGPT and Copilot.
For very simple test cases of simple methods/functions it's ok. Once code starts to complicate, you'll lose much more time trying to steer the LLM into writing what you need, than simply doing it yourself. In particular setting up and creating mocks seems where the most difficulty lies.
Once you create the test, you can use the LLM as a code completion tool, to test for more things once you get a complex result. Or you can ask it to extrapolate from test data to create more test cases.