Tests - The Cargo Book

## Tests

Cargo can run your tests with the `cargo test` command. Cargo looks for tests to run in two places: in each of your `src` files and any tests in `tests/`. Tests in your `src` files should be unit tests, and tests in `tests/` should be integration-style tests. As such, you’ll need to import your crates into the files in `tests`.

Here's an example of running `cargo test` in our package, which currently has no tests:

    $ cargo test
       Compiling rand v0.1.0 (https://github.com/rust-lang-nursery/rand.git#9f35b8e)
       Compiling hello_world v0.1.0 (file:///path/to/package/hello_world)
         Running target/test/hello_world-9c2b65bbb79eabce

    running 0 tests

    test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out

If our package had tests, we would see more output with the correct number of tests.

You can also run a specific test by passing a filter:

    $ cargo test foo

This will run any test with `foo` in its name.

`cargo test` runs additional checks as well. For example, it will compile any examples you’ve included and will also test the examples in your documentation. Please see the testing guide in the Rust documentation for more details.