cargo test - The Cargo Book

# 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 and integration 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`.

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 an executable with a `main` function that 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.

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 and executes them. See the rustdoc book for more information on writing doc tests.

## 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. Setting targets to `test = false` will stop them from being tested by default. Target selection options that take a target by name 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.

Binary targets are automatically built if there is an integration test or benchmark. 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.

`--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 in test mode 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 in benchmark mode 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 the enabled features for the "current" package. The "current" package is the package in the current directory, or the one specified in `--manifest-path`. If running in the root of a virtual workspace, then the default features are selected for all workspace members, or all features if `--all-features` is specified.

When no feature options are given, the `default` feature is activated for every selected package.

`--features` features
  Space or comma separated list of features to activate. These features only apply to the current directory's package. Features of direct dependencies may be enabled with `<dep-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 current directory's package.

### Compilation Options

`--target` triple
  Test for the given architecture. The default is the host architecture. The general format of the triple is `<arch><sub>-<vendor>-<sys>-<abi>`. Run `rustc --print target-list` for a list of supported targets.

  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.

`--release`
  Test optimized artifacts with the `release` profile. See the PROFILES section for details on how this affects profile selection.

### 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 `--nocapture` to the test binaries:

    cargo test -- --nocapture

`-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`
  No output printed to stdout.
`--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.
  - `short`: Emit shorter, human-readable text messages.
  - `json`: Emit JSON messages to stdout. See the reference for more details.
  - `json-diagnostic-short`: Ensure the `rendered` field of JSON messages contains the "short" rendering from rustc.
  - `json-diagnostic-rendered-ansi`: Ensure the `rendered` field of JSON messages contains embedded ANSI color codes for respecting rustc's default color scheme.
  - `json-render-diagnostics`: Instruct Cargo to not include rustc diagnostics in 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.

### 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.
`--frozen`
`--locked`
  Either of these flags requires that the `Cargo.lock` file is up-to-date. If the lock file is missing, or it needs to be updated, Cargo will exit with an error. The `--frozen` flag also prevents Cargo from attempting to access the network to determine if it is out-of-date.

  These may be used in environments where you want to assert that the `Cargo.lock` file is up-to-date (such as a CI build) or want to avoid network access.

`--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.

### 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.
`-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 CPUs.

## PROFILES

Profiles may be used to configure compiler options such as optimization levels and debug settings. See the reference for more details.

Profile selection depends on the target and crate being built. By default the `dev` or `test` profiles are used. If the `--release` flag is given, then the `release` or `bench` profiles are used.

Target | Default Profile | `--release` Profile
--- | --- | ---
lib, bin, example | `dev` | `release`
test, bench, or any target in "test" or "bench" mode | `test` | `bench`

Dependencies use the `dev`/`release` profiles.

Unit tests are separate executable artifacts which use the `test`/`bench` profiles. Example targets are built the same as with `cargo build` (using the `dev`/`release` profiles) unless you are building them with the test harness (by setting `test = true` in the manifest or using the `--example` flag) in which case they use the `test`/`bench` profiles. Library targets are built with the `dev`/`release` profiles when linked to an integration test, binary, or doctest.

## 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)