cargo test - The Cargo Book

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# cargo-test(1)

## NAME

cargo-test — Execute unit and integration tests of a package

## SYNOPSIS

`cargo test` [options] [testname] [`--` test-options]

## DESCRIPTION

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

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.

### Working directory of 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.

## OPTIONS

### Test Options

`--no-run`

  Compile, but don’t run tests.

`--no-fail-fast`

  Run all tests regardless of failure. Without this flag, Cargo will exit after the first executable fails. The Rust test harness will run all tests within the executable to completion, this flag only applies to the executable as a whole.

### Package Selection

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.

`-p` spec…
`--package` spec…

  Test only the specified packages. See cargo-pkgid(1) for the SPEC format. This flag may be specified multiple times and supports 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 pattern.

`--workspace`

  Test all members in the workspace.

`--all`

  Deprecated alias for `--workspace`.

`--exclude` SPEC…

  Exclude the specified packages. Must be used in conjunction with the `--workspace` flag. This flag may be specified multiple times and supports 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 pattern.

### Target Selection

When no target selection options are given, `cargo test` will build the following targets of the selected packages:

- lib — used to link with binaries, examples, integration tests, and doc tests
- bins (only if integration tests are built and required features are available)
- examples — to ensure they compile
- lib as a unit test
- bins as unit tests
- integration tests
- doc tests for the lib target

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 and run so that it can use the `env` macro or the `var` function 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.

`--lib`

  Test the package’s library.

`--bin` name…

  Test the specified binary. This flag may be specified multiple times and supports common Unix glob patterns.

`--bins`

  Test all binary targets.

`--example` name…

  Test the specified example. This flag may be specified multiple times and supports common Unix glob patterns.

`--examples`

  Test all example targets.

`--test` name…

  Test the specified integration test. This flag may be specified multiple times and supports common Unix glob patterns.

`--tests`

  Test all targets that have the `test = true` manifest flag set. By default this includes the library and binaries built as unittests, and integration tests. Be aware that this will also build any required dependencies, so the lib target may be built twice (once as a unittest, and once as a dependency for binaries, integration tests, etc.). Targets may be enabled or disabled by setting the `test` flag in the manifest settings for the target.

`--bench` name…

  Test the specified benchmark. This flag may be specified multiple times and supports common Unix glob patterns.

`--benches`

  Test all targets that have the `bench = true` manifest flag set. By default this includes the library and binaries built as benchmarks, and bench targets. Be aware that this will also build any required dependencies, so the lib target may be built twice (once as a benchmark, and once as a dependency for binaries, benchmarks, etc.). Targets may be enabled or disabled by setting the `bench` flag in the manifest settings for the target.

`--all-targets`

  Test all targets. This is equivalent to specifying `--lib --bins --tests --benches --examples`.

`--doc`

  Test only the library’s documentation. This cannot be mixed with other target options.

### Feature Selection

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.

`-F` features
`--features` features

  Space or comma separated list of features to activate. Features of workspace members may be enabled with `package-name/feature-name` syntax. This flag may be specified multiple times, which enables all specified features.

`--all-features`

  Activate all available features of all selected packages.

`--no-default-features`

  Do not activate the `default` feature of the selected packages.

### Compilation Options

`--target` triple

  Test for the specified target architecture. Flag may be specified multiple times. The default is the host architecture. The general format of the triple is `<arch><sub>-<vendor>-<sys>-<abi>`.

  Possible values:

  - Any supported target in `rustc --print target-list`.
  - `"host-tuple"`, which will internally be substituted by the host’s target. This can be particularly useful if you’re cross-compiling some crates, and don’t want to specify your host’s machine as a target (for instance, an `xtask` in a shared project that may be worked on by many hosts).
  - A path to a custom target specification. See Custom Target Lookup Path for more information.

  This may also be specified with the `build.target` config value.

  Note that specifying this flag makes Cargo run in a different mode where the target artifacts are placed in a separate directory. See the build cache documentation for more details.

`-r`
`--release`

  Test optimized artifacts with the `release` profile. See also the `--profile` option for choosing a specific profile by name.

`--profile` name

  Test with the given profile. See the reference for more details on profiles.

`--timings`

  Output information how long each compilation takes, and track concurrency information over time.

  A file `cargo-timing.html` will be written to the `target/cargo-timings` directory at the end of the build. An additional report with a timestamp in its filename is also written if you want to look at a previous run. These reports are suitable for human consumption only, and do not provide machine-readable timing data.

### Output Options

`--target-dir` directory

  Directory for all generated artifacts and intermediate files. May also be specified with the `CARGO_TARGET_DIR` environment variable, or the `build.target-dir` config value. Defaults to `target` in the root of the workspace.

### Display Options

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 `--no-capture` to the test binaries:

    cargo test -- --no-capture

`-v`
`--verbose`

  Use verbose output. May be specified twice for “very verbose” output which includes extra output such as dependency warnings and build script output. May also be specified with the `term.verbose` config value.

`-q`
`--quiet`

  Do not print cargo log messages. May also be specified with the `term.quiet` config value.

`--color` when

  Control when colored output is used. Valid values:

  - `auto` (default): Automatically detect if color support is available on the terminal.
  - `always`: Always display colors.
  - `never`: Never display colors.

  May also be specified with the `term.color` config value.

`--message-format` fmt

  The output format for diagnostic messages. Can be specified multiple times and consists of comma-separated values. Valid values:

  - `human` (default): Display in a human-readable text format. Conflicts with `short` and `json`.
  - `short`: Emit shorter, human-readable text messages. Conflicts with `human` and `json`.
  - `json`: Emit JSON messages to stdout. See the reference for more details. Conflicts with `human` and `short`.
  - `json-diagnostic-short`: Ensure the `rendered` field of JSON messages contains the “short” rendering from rustc. Cannot be used with `human` or `short`.
  - `json-diagnostic-rendered-ansi`: Ensure the `rendered` field of JSON messages contains embedded ANSI color codes for respecting rustc’s default color scheme. Cannot be used with `human` or `short`.
  - `json-render-diagnostics`: Instruct Cargo to not include rustc diagnostics in JSON messages printed, but instead Cargo itself should render the JSON diagnostics coming from rustc. Cargo’s own JSON diagnostics and others coming from rustc are still emitted. Cannot be used with `human` or `short`.

### Manifest Options

`--manifest-path` path

  Path to the `Cargo.toml` file. By default, Cargo searches for the `Cargo.toml` file in the current directory or any parent directory.

`--ignore-rust-version`

  Ignore `rust-version` specification in packages.

`--locked`

  Asserts that the exact same dependencies and versions are used as when the existing `Cargo.lock` file was originally generated. Cargo will exit with an error when either of the following scenarios arises:

  - The lock file is missing.
  - Cargo attempted to change the lock file due to a different dependency resolution.

  It may be used in environments where deterministic builds are desired, such as in CI pipelines.

`--offline`

  Prevents Cargo from accessing the network for any reason. Without this flag, Cargo will stop with an error if it needs to access the network and the network is not available. With this flag, Cargo will attempt to proceed without the network if possible.

  Beware that this may result in different dependency resolution than online mode. Cargo will restrict itself to crates that are downloaded locally, even if there might be a newer version as indicated in the local copy of the index. See the cargo-fetch(1) command to download dependencies before going offline.

  May also be specified with the `net.offline` config value.

`--frozen`

  Equivalent to specifying both `--locked` and `--offline`.

### Common Options

`+`toolchain

  If Cargo has been installed with rustup, and the first argument to `cargo` begins with `+`, it will be interpreted as a rustup toolchain name (such as `+stable` or `+nightly`). See the rustup documentation for more information about how toolchain overrides work.

`--config` KEY=VALUE or PATH

  Overrides a Cargo configuration value. The argument should be in TOML syntax of `KEY=VALUE`, or provided as a path to an extra configuration file. This flag may be specified multiple times. See the command-line overrides section for more information.

`-C` PATH

  Changes the current working directory before executing any specified operations. This affects things like where cargo looks by default for the project manifest (`Cargo.toml`), as well as the directories searched for discovering `.cargo/config.toml`, for example. This option must appear before the command name, for example `cargo -C path/to/my-project build`.

  This option is only available on the nightly channel and requires the `-Z unstable-options` flag to enable (see #10098).

`-h`
`--help`

  Prints help information.

`-Z` flag

  Unstable (nightly-only) flags to Cargo. Run `cargo -Z help` for details.

### Miscellaneous Options

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

`-j` N
`--jobs` N

  Number of parallel jobs to run. May also be specified with the `build.jobs` config value. Defaults to the number of logical CPUs. If negative, it sets the maximum number of parallel jobs to the number of logical CPUs plus provided value. If a string `default` is provided, it sets the value back to defaults. Should not be 0.

`--future-incompat-report`

  Displays a future-incompat report for any future-incompatible warnings produced during execution of this command

  See cargo-report(1)

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

## ENVIRONMENT

See the reference for details on environment variables that Cargo reads.

## EXIT STATUS

- `0`: Cargo succeeded.
- `101`: Cargo failed to complete.

## EXAMPLES

1. Execute all the unit and integration tests of the current package:

       cargo test

2. Run only tests whose names match against a filter string:

       cargo test name_filter

3. Run only a specific test within a specific integration test:

       cargo test --test int_test_name -- modname::test_name

## SEE ALSO

cargo(1), cargo-bench(1), types of tests, how to write tests