cargo-test --- Execute unit and integration tests of a package
cargo test
[options] [testname] [--
test-options]
Compile and execute unit, integration, and documentation tests.
The test filtering argument TESTNAME
and all the arguments following the two dashes (--
) are passed to the test binaries and thus to libtest (rustc‘s built in unit-test and micro-benchmarking framework). If you’re passing arguments to both Cargo and the binary, the ones after --
go to the binary, the ones before go to Cargo. For details about libtest‘s arguments see the output of cargo test -- --help
and check out the rustc book’s chapter on how tests work at https://doc.rust-lang.org/rustc/tests/index.html.
As an example, this will filter for tests with foo
in their name and run them on 3 threads in parallel:
cargo test foo -- --test-threads 3
Tests are built with the --test
option to rustc
which creates a special executable by linking your code with libtest. The executable automatically runs all functions annotated with the #[test]
attribute in multiple threads. #[bench]
annotated functions will also be run with one iteration to verify that they are functional.
If the package contains multiple test targets, each target compiles to a special executable as aforementioned, and then is run serially.
The libtest harness may be disabled by setting harness = false
in the target manifest settings, in which case your code will need to provide its own main
function to handle running tests.
Documentation tests are also run by default, which is handled by rustdoc
. It extracts code samples from documentation comments of the library target, and then executes them.
Different from normal test targets, each code block compiles to a doctest executable on the fly with rustc
. These executables run in parallel in separate processes. The compilation of a code block is in fact a part of test function controlled by libtest, so some options such as --jobs
might not take effect. Note that this execution model of doctests is not guaranteed and may change in the future; beware of depending on it.
See the rustdoc book for more information on writing doc tests.
The working directory when running each unit and integration test is set to the root directory of the package the test belongs to. Setting the working directory of tests to the package‘s root directory makes it possible for tests to reliably access the package’s files using relative paths, regardless from where cargo test
was executed from.
For documentation tests, the working directory when invoking rustdoc
is set to the workspace root directory, and is also the directory rustdoc
uses as the compilation directory of each documentation test. The working directory when running each documentation test is set to the root directory of the package the test belongs to, and is controlled via rustdoc
's --test-run-directory
option.
By default, when no package selection options are given, the packages selected depend on the selected manifest file (based on the current working directory if --manifest-path
is not given). If the manifest is the root of a workspace then the workspaces default members are selected, otherwise only the package defined by the manifest will be selected.
The default members of a workspace can be set explicitly with the workspace.default-members
key in the root manifest. If this is not set, a virtual workspace will include all workspace members (equivalent to passing --workspace
), and a non-virtual workspace will include only the root crate itself.
When no target selection options are given, cargo test
will build the following targets of the selected packages:
The default behavior can be changed by setting the test
flag for the target in the manifest settings. Setting examples to test = true
will build and run the example as a test, replacing the example‘s main
function with the libtest harness. If you don’t want the main
function replaced, also include harness = false
, in which case the example will be built and executed as-is.
Setting targets to test = false
will stop them from being tested by default. Target selection options that take a target by name (such as --example foo
) ignore the test
flag and will always test the given target.
Doc tests for libraries may be disabled by setting doctest = false
for the library in the manifest.
See Configuring a target for more information on per-target settings.
Binary targets are automatically built if there is an integration test or benchmark being selected to test. This allows an integration test to execute the binary to exercise and test its behavior. The CARGO_BIN_EXE_<name>
environment variable is set when the integration test is built so that it can use the env
macro to locate the executable.
Passing target selection flags will test only the specified targets.
Note that --bin
, --example
, --test
and --bench
flags also support common Unix glob patterns like *
, ?
and []
. However, to avoid your shell accidentally expanding glob patterns before Cargo handles them, you must use single quotes or double quotes around each glob pattern.
The feature flags allow you to control which features are enabled. When no feature options are given, the default
feature is activated for every selected package.
See the features documentation for more details.
By default the Rust test harness hides output from test execution to keep results readable. Test output can be recovered (e.g., for debugging) by passing --nocapture
to the test binaries:
cargo test -- --nocapture
The --jobs
argument affects the building of the test executable but does not affect how many threads are used when running the tests. The Rust test harness includes an option to control the number of threads used:
cargo test -j 2 -- --test-threads=2
While cargo test
involves compilation, it does not provide a --keep-going
flag. Use --no-fail-fast
to run as many tests as possible without stopping at the first failure. To “compile” as many tests as possible, use --tests
to build test binaries separately. For example:
cargo build --tests --keep-going cargo test --tests --no-fail-fast
See the reference for details on environment variables that Cargo reads.
0
: Cargo succeeded.101
: Cargo failed to complete.Execute all the unit and integration tests of the current package:
cargo test
Run only tests whose names match against a filter string:
cargo test name_filter
Run only a specific test within a specific integration test:
cargo test --test int_test_name -- modname::test_name
cargo(1), cargo-bench(1), types of tests, how to write tests