Question 1

How do I run only the slow tests in Alcotest?

Accepted Answer

Slow tests are marked with `` `Slow`` and run by default unless you use the `-q` flag to suppress them. For example, run `./test.exe` for all tests or `./test.exe -q` for quick tests only, as explained in the Quick and Slow tests section.

Question 2

Alcotest vs OUnit: which is better for OCaml?

Accepted Answer

Alcotest is often preferred for its cleaner, colorful output and combinators, while OUnit might have more assertion types. The README states Alcotest fixes OUnit issues like nicer logs, but choose based on your need for simplicity versus feature richness.

Question 3

How can I pass command line arguments to my Alcotest tests?

Accepted Answer

Use Cmdliner terms to define custom arguments in the `run_with_args` function. For instance, define a term for an integer option `-n`, as shown in the example, allowing tests to accept parameters like `./test.exe test -n 42`.

Question 4

Does Alcotest support async tests with Lwt?

Accepted Answer

Yes, via the Alcotest_lwt module, which wraps Lwt test cases, handles async exceptions without crashing, and provides switches for resource cleanup. The README includes a code snippet demonstrating this with `Lwt_main.run`.

Question 5

How to filter tests by name in Alcotest?

Accepted Answer

Use regular expressions with the test command, e.g., `./test.exe test '.*concat*'`. However, note that filtering is limited to test suite names and numbers, not individual case names, as mentioned in the selecting tests section.

Question 6

Can Alcotest generate code coverage reports?

Accepted Answer

No, Alcotest focuses on test execution and output; for coverage reports, you need external tools like Bisect_ppx or other OCaml instrumentation, as it's not a built-in feature.

Alcotest

What is Alcotest?

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Frequently Asked Questions