Programming with Mosh on YouTube · Open on YouTube
Professional practice · Competent · Lesson 32 of 98 · 49 min video, then about 9 hours of practice
Automated testing: unit and integration tests
After this you can write unit tests for logic and integration tests for an API endpoint, and decide what is worth testing.
Why it matters
Tests are how you change code without fear and how teammates know your change did not break theirs. Juniors who write tests unprompted stand out immediately. Focus on testing behaviour rather than implementation, the arrange-act-assert shape, and integration tests that hit a real test database through your API. Learn to write a failing test that reproduces a bug before fixing it. Trap: chasing a coverage number. One test of a tricky edge case is worth ten tests of getters.
How to use this resource
Unit testing fundamentals, clearly explained. The ideas transfer directly to Vitest.
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