Travis CI tools read the instruction specified in the .travis.yml file of the project and prepare the environment in which you want to build, test, and release the project.

In the next section, we will break down and understand what each of the commands does in the build pipeline:

      language: rust

This downloads and installs the latest stable version of the Rust release when setting up the machine. If you only want to test the application in a stable version, you just need the preceding command and there is no need to specify the versions:

rust:
 - stable
 - beta
 - nightly

For specifying the versions in which you want to test the application, you can use the preceding command where you built the project in the beta and nightly channels. Even if you are only targeting stable, the Rust team encourages you to test it on other channels as well:

matrix:
 allow_failures:
 - rust: nightly

This will test all three channels, and any breakage in nightly will not fail your overall build.

In the preceding build logs, if you look closely, you will see the default test script is run by the Travis CI, and it uses the Cargo tool to run your build and test the application using cargo build and cargo test commands.