Attribute Macro cargo_test

#[cargo_test]

Replacement for #[test]

The #[cargo_test] attribute extends #[test] with some setup before starting the test. It will create a filesystem “sandbox” under the “cargo integration test” directory for each test, such as /path/to/cargo/target/tmp/cit/t123/. The sandbox will contain a home directory that will be used instead of your normal home directory.

The #[cargo_test] attribute takes several options that will affect how the test is generated. They are listed in parentheses separated with commas, such as:

#[cargo_test(nightly, reason = "-Zfoo is unstable")]

The options it supports are:

• >=1.64 — This indicates that the test will only run with the given version of rustc or newer. This can be used when a new rustc feature has been stabilized that the test depends on. If this is specified, a reason is required to explain why it is being checked.
• nightly — This will cause the test to be ignored if not running on the nightly toolchain. This is useful for tests that use unstable options in rustc or rustdoc. These tests are run in Cargo’s CI, but are disabled in rust-lang/rust’s CI due to the difficulty of updating both repos simultaneously. A reason field is required to explain why it is nightly-only.
• requires_<cmd> — This indicates a command that is required to be installed to be run. For example, requires_rustfmt means the test will only run if the executable rustfmt is installed. These tests are always run on CI. This is mainly used to avoid requiring contributors from having every dependency installed.
• build_std_real — This is a “real” -Zbuild-std test (in the build_std integration test). This only runs on nightly, and only if the environment variable CARGO_RUN_BUILD_STD_TESTS is set (these tests on run on Linux).
• build_std_mock — This is a “mock” -Zbuild-std test (which uses a mock standard library). This only runs on nightly, and is disabled for windows-gnu.
• public_network_test — This tests contacts the public internet. These tests are disabled unless the CARGO_PUBLIC_NETWORK_TESTS environment variable is set. Use of this should be extremely rare, please avoid using it if possible. The hosts it contacts should have a relatively high confidence that they are reliable and stable (such as github.com), especially in CI. The tests should be carefully considered for developer security and privacy as well.
• container_test — This indicates that it is a test that uses Docker. These tests are disabled unless the CARGO_CONTAINER_TESTS environment variable is set. This requires that you have Docker installed. The SSH tests also assume that you have OpenSSH installed. These should work on Linux, macOS, and Windows where possible. Unfortunately these tests are not run in CI for macOS or Windows (no Docker on macOS, and Windows does not support Linux images). See cargo-test-support::containers for more on writing these tests.
• ignore_windows="reason" — Indicates that the test should be ignored on windows for the given reason.