AI For Test Generation: Where It Helps And Where It Lies
AI writes tests fast. It also writes tests that look real but verify the wrong things. You might see your coverage go up, but your code remains broken.
AI is great for certain tasks. Use it to:
- Extrapolate from a good example. If you write one perfect test, AI can write ten more in your exact style.
- Handle repetitive typing. Use it for setup blocks, teardown, and factory helpers.
- Create initial scaffolding. It gets you to the editor faster than a blank file.
The danger starts when you let AI decide the "contract."
If you give AI a function and ask for tests, it reads the code and tests what the code currently does. It does not test what the code should do. This creates a closed loop. The AI makes an assumption, writes the code, and then writes tests that agree with that same assumption.
When bugs hit production, they hit because the test suite was on the side of the bug.
Watch out for these three traps:
Implementation-shaped tests AI often tests the logic paths instead of the business rules. If you change a small internal detail, the tests break even if the result is still correct. This makes refactoring a nightmare.
Shallow edge cases AI is good at testing nulls, empty strings, and zeros. These are obvious. It cannot find "domain edges." It does not know your specific timezone bugs, your database quirks, or your unique business rules.
Brittle mocks AI loves to mock everything. This leads to two problems:
- The mock is wrong. It mimics a fake version of an API that does not match reality.
- The mock freezes the implementation. It tests how your code calls other functions rather than testing the final outcome.
How to use AI correctly:
Keep the "intent" out of the AI's reach.
- Write the contract first. Write one sentence in plain English for every test. Example: "Expired codes must return the original amount."
- Hand those sentences to the AI. Let it write the assertions, but you provide the meaning.
- Mock at the boundaries. Only mock external APIs or databases. Use real versions of your own internal modules.
- Write one domain edge case by hand. Every time you finish a function, write down the one thing that scares you. Use that as a prompt for the AI.
AI is a productivity tool, not a replacement for thinking. Use it to write the body of the test, but never let it decide what the test is for.
Source: https://dev.to/nazar_boyko/ai-for-test-generation-where-it-helps-and-where-it-lies-jhm
Optional learning community: https://t.me/GyaanSetuAi