Crate libtest2_mimic Copy item path

An experimental replacement for libtest-mimic

Write your own tests that look and behave like built-in tests!

This is a simple and small test harness that mimics the original libtest (used by cargo test/rustc --test). That means: all output looks pretty much like cargo test and most CLI arguments are understood and used. With that plumbing work out of the way, your test runner can focus on the actual testing.

For a small real world example, see examples/mimic-tidy.rs.

§Usage

To use this, you most likely want to add a manual [[test]] section to Cargo.toml and set harness = false. For example:

[[test]]
name = "mytest"
path = "tests/mytest.rs"
harness = false

And in tests/mytest.rs you would call Harness::main in the main function:

Harness::with_env()
    .discover([
        Trial::test("succeeding_test", move |_| Ok(())),
        Trial::test("failing_test", move |_| Err(RunError::fail("Woops"))),
    ])
    .main();

Instead of returning Ok or Err directly, you want to actually perform your tests, of course. See Trial::test for more information on how to define a test. You can of course list all your tests manually. But in many cases it is useful to generate one test per file in a directory, for example.

You can then run cargo test --test mytest to run it. To see the CLI arguments supported by this crate, run cargo test --test mytest -- -h.

§Known limitations and differences to the official test harness

libtest2-mimic aims to be fully compatible with stable, non-deprecated parts of libtest but there are differences for now.

Some of the notable differences:

• Output capture and --no-capture: simply not supported. The official libtest uses internal std functions to temporarily redirect output. libtest-mimic cannot use those, see also libtest2#12
• --format=json (unstable): our schema is part of an experiment to see what should be stabilized for libtest, see also libtest2#42