Question 1

How to use test-each with Jest for data-driven tests?

Accepted Answer

Import the `each` function and call it with your inputs, then wrap the callback in Jest's `test` function, appending the generated title. The README shows an example with Ava, but it works similarly with Jest by replacing the test runner call.

Question 2

test-each vs Jest's test.each: which should I use?

Accepted Answer

Use test-each if you need advanced features like cartesian products, fuzz testing, or support for non-array inputs and complex JavaScript types. Jest's built-in `test.each` is simpler but limited to array inputs and less flexible title generation.

Question 3

How to generate random test data with test-each and faker.js?

Accepted Answer

Pass an integer for iterations and a function that returns random data, like `faker.random.uuid`, as shown in the 'Fuzz testing' section. Use `info.index` as a seed for reproducible randomness across test runs.

Question 4

Can test-each handle asynchronous test functions?

Accepted Answer

Yes, it works with async tests since it's just a utility for iterating inputs; the callback can contain async logic, but you must handle promises appropriately in your test runner (e.g., using async/await in Ava or Jest).

Question 5

Is test-each compatible with TypeScript and how do I set it up?

Accepted Answer

Yes, it has TypeScript definitions included, as indicated by the badge. Ensure your TypeScript config outputs ES modules, and import it normally; the types will provide autocomplete for the `each` and `iterable` functions.

Question 6

How to avoid side effects when modifying parameters in test-each?

Accepted Answer

Copy parameters before mutating them, as advised in the 'Side effects' section. For example, use object spread syntax (`{ ...param }`) to create a new object, preventing changes from affecting subsequent iterations.

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