Defs

• rust_binary
• rust_library
• rust_static_library
• rust_shared_library
• rust_proc_macro
• rust_test
• rust_test_suite
• error_format
• extra_rustc_flag
• extra_rustc_flags
• capture_clippy_output

capture_clippy_output

Control whether to print clippy output or store it to a file, using the configured error_format.

ATTRIBUTES

Name	Description	Type	Mandatory	Default
name	A unique name for this target.	Name	required

error_format

Change the --error-format flag from the command line with --@rules_rust//:error_format. See rustc documentation for valid values.

ATTRIBUTES

Name	Description	Type	Mandatory	Default
name	A unique name for this target.	Name	required

extra_rustc_flag

Add additional rustc_flag from the command line with --@rules_rust//:extra_rustc_flag. Multiple uses are accumulated and appended after the extra_rustc_flags.

ATTRIBUTES

Name	Description	Type	Mandatory	Default
name	A unique name for this target.	Name	required

extra_rustc_flags

Add additional rustc_flags from the command line with --@rules_rust//:extra_rustc_flags. This flag should only be used for flags that need to be applied across the entire build. For options that apply to individual crates, use the rustc_flags attribute on the individual crate's rule instead. NOTE: These flags not applied to the exec configuration (proc-macros, cargo_build_script, etc); use --@rules_rust//:extra_exec_rustc_flags to apply flags to the exec configuration.

ATTRIBUTES

Name	Description	Type	Mandatory	Default
name	A unique name for this target.	Name	required

rust_binary

Builds a Rust binary crate.

Example:

Suppose you have the following directory structure for a Rust project with a library crate, hello_lib, and a binary crate, hello_world that uses the hello_lib library:

[workspace]/
    WORKSPACE
    hello_lib/
        BUILD
        src/
            lib.rs
    hello_world/
        BUILD
        src/
            main.rs

hello_lib/src/lib.rs:

pub struct Greeter {
    greeting: String,
}

impl Greeter {
    pub fn new(greeting: &str) -> Greeter {
        Greeter { greeting: greeting.to_string(), }
    }

    pub fn greet(&self, thing: &str) {
        println!("{} {}", &self.greeting, thing);
    }
}

hello_lib/BUILD:

package(default_visibility = ["//visibility:public"])

load("@rules_rust//rust:defs.bzl", "rust_library")

rust_library(
    name = "hello_lib",
    srcs = ["src/lib.rs"],
)

hello_world/src/main.rs:

extern crate hello_lib;

fn main() {
    let hello = hello_lib::Greeter::new("Hello");
    hello.greet("world");
}

hello_world/BUILD:

load("@rules_rust//rust:defs.bzl", "rust_binary")

rust_binary(
    name = "hello_world",
    srcs = ["src/main.rs"],
    deps = ["//hello_lib"],
)

Build and run hello_world:

$ bazel run //hello_world
INFO: Found 1 target...
Target //examples/rust/hello_world:hello_world up-to-date:
bazel-bin/examples/rust/hello_world/hello_world
INFO: Elapsed time: 1.308s, Critical Path: 1.22s

INFO: Running command line: bazel-bin/examples/rust/hello_world/hello_world
Hello world

On Windows, a PDB file containing debugging information is available under the key pdb_file in OutputGroupInfo. Similarly on macOS, a dSYM folder is available under the key dsym_folder in OutputGroupInfo.

ATTRIBUTES

Name	Description	Type	Mandatory	Default
name	A unique name for this target.	Name	required
aliases	Remap crates to a new name or moniker for linkage to this target These are other rust_library targets and will be presented as the new name given.	Dictionary: Label -> String	optional	{}
compile_data	List of files used by this rule at compile time. This attribute can be used to specify any data files that are embedded into the library, such as via the include_str! macro.	List of labels	optional	[]
crate_features	List of features to enable for this crate. Features are defined in the code using the #[cfg(feature = “foo”)] configuration option. The features listed here will be passed to rustc with --cfg feature=“${feature_name}” flags.	List of strings	optional	[]
crate_name	Crate name to use for this target. This must be a valid Rust identifier, i.e. it may contain only alphanumeric characters and underscores. Defaults to the target name, with any hyphens replaced by underscores.	String	optional	""
crate_root	The file that will be passed to rustc to be used for building this crate. If crate_root is not set, then this rule will look for a lib.rs file (or main.rs for rust_binary) or the single file in srcs if srcs contains only one file.	Label	optional	None
crate_type	Crate type that will be passed to rustc to be used for building this crate. This option is a temporary workaround and should be used only when building for WebAssembly targets (//rust/platform:wasi and //rust/platform:wasm).	String	optional	“bin”
data	List of files used by this rule at compile time and runtime. If including data at compile time with include_str!() and similar, prefer compile_data over data, to prevent the data also being included in the runfiles.	List of labels	optional	[]
deps	List of other libraries to be linked to this library target. These can be either other rust_library targets or cc_library targets if linking a native library.	List of labels	optional	[]
edition	The rust edition to use for this crate. Defaults to the edition specified in the rust_toolchain.	String	optional	""
experimental_use_cc_common_link	Whether to use cc_common.link to link rust binaries. Possible values: [-1, 0, 1]. -1 means use the value of the toolchain.experimental_use_cc_common_link boolean build setting to determine. 0 means do not use cc_common.link (use rustc instead). 1 means use cc_common.link.	Integer	optional	-1
linker_script	Link script to forward into linker via rustc options.	Label	optional	None
out_binary	Force a target, regardless of it's crate_type, to always mark the file as executable. This attribute is only used to support wasm targets but is expected to be removed following a resolution to https://github.com/bazelbuild/rules_rust/issues/771.	Boolean	optional	False
proc_macro_deps	List of rust_library targets with kind proc-macro used to help build this library target.	List of labels	optional	[]
rustc_env	Dictionary of additional “key”: “value” environment variables to set for rustc. rust_test()/rust_binary() rules can use $(rootpath //package:target) to pass in the location of a generated file or external tool. Cargo build scripts that wish to expand locations should use cargo_build_script()'s build_script_env argument instead, as build scripts are run in a different environment - see cargo_build_script()'s documentation for more.	Dictionary: String -> String	optional	{}
rustc_env_files	Files containing additional environment variables to set for rustc. These files should contain a single variable per line, of format NAME=value, and newlines may be included in a value by ending a line with a trailing back-slash (\). The order that these files will be processed is unspecified, so multiple definitions of a particular variable are discouraged. Note that the variables here are subject to workspace status stamping should the stamp attribute be enabled. Stamp variables should be wrapped in brackets in order to be resolved. E.g. NAME={WORKSPACE_STATUS_VARIABLE}.	List of labels	optional	[]
rustc_flags	List of compiler flags passed to rustc. These strings are subject to Make variable expansion for predefined source/output path variables like $location, $execpath, and $rootpath. This expansion is useful if you wish to pass a generated file of arguments to rustc: @$(location //package:target).	List of strings	optional	[]
srcs	List of Rust .rs source files used to build the library. If srcs contains more than one file, then there must be a file either named lib.rs. Otherwise, crate_root must be set to the source file that is the root of the crate to be passed to rustc to build this crate.	List of labels	optional	[]
stamp	Whether to encode build information into the Rustc action. Possible values: - stamp = 1: Always stamp the build information into the Rustc action, even in --nostamp builds. This setting should be avoided, since it potentially kills remote caching for the target and any downstream actions that depend on it. - stamp = 0: Always replace build information by constant values. This gives good build result caching. - stamp = -1: Embedding of build information is controlled by the --[no]stamp flag. Stamped targets are not rebuilt unless their dependencies change. For example if a rust_library is stamped, and a rust_binary depends on that library, the stamped library won't be rebuilt when we change sources of the rust_binary. This is different from how cc_library.linkstamps behaves.	Integer	optional	-1
version	A version to inject in the cargo environment variable.	String	optional	“0.0.0”

rust_library

Builds a Rust library crate.

Example:

Suppose you have the following directory structure for a simple Rust library crate:

[workspace]/
    WORKSPACE
    hello_lib/
        BUILD
        src/
            greeter.rs
            lib.rs

hello_lib/src/greeter.rs:

pub struct Greeter {
    greeting: String,
}

impl Greeter {
    pub fn new(greeting: &str) -> Greeter {
        Greeter { greeting: greeting.to_string(), }
    }

    pub fn greet(&self, thing: &str) {
        println!("{} {}", &self.greeting, thing);
    }
}

hello_lib/src/lib.rs:

pub mod greeter;

hello_lib/BUILD:

package(default_visibility = ["//visibility:public"])

load("@rules_rust//rust:defs.bzl", "rust_library")

rust_library(
    name = "hello_lib",
    srcs = [
        "src/greeter.rs",
        "src/lib.rs",
    ],
)

Build the library:

$ bazel build //hello_lib
INFO: Found 1 target...
Target //examples/rust/hello_lib:hello_lib up-to-date:
bazel-bin/examples/rust/hello_lib/libhello_lib.rlib
INFO: Elapsed time: 1.245s, Critical Path: 1.01s

ATTRIBUTES

Name	Description	Type	Mandatory	Default
name	A unique name for this target.	Name	required
aliases	Remap crates to a new name or moniker for linkage to this target These are other rust_library targets and will be presented as the new name given.	Dictionary: Label -> String	optional	{}
compile_data	List of files used by this rule at compile time. This attribute can be used to specify any data files that are embedded into the library, such as via the include_str! macro.	List of labels	optional	[]
crate_features	List of features to enable for this crate. Features are defined in the code using the #[cfg(feature = “foo”)] configuration option. The features listed here will be passed to rustc with --cfg feature=“${feature_name}” flags.	List of strings	optional	[]
crate_name	Crate name to use for this target. This must be a valid Rust identifier, i.e. it may contain only alphanumeric characters and underscores. Defaults to the target name, with any hyphens replaced by underscores.	String	optional	""
crate_root	The file that will be passed to rustc to be used for building this crate. If crate_root is not set, then this rule will look for a lib.rs file (or main.rs for rust_binary) or the single file in srcs if srcs contains only one file.	Label	optional	None
data	List of files used by this rule at compile time and runtime. If including data at compile time with include_str!() and similar, prefer compile_data over data, to prevent the data also being included in the runfiles.	List of labels	optional	[]
deps	List of other libraries to be linked to this library target. These can be either other rust_library targets or cc_library targets if linking a native library.	List of labels	optional	[]
disable_pipelining	Disables pipelining for this rule if it is globally enabled. This will cause this rule to not produce a .rmeta file and all the dependent crates will instead use the .rlib file.	Boolean	optional	False
edition	The rust edition to use for this crate. Defaults to the edition specified in the rust_toolchain.	String	optional	""
proc_macro_deps	List of rust_library targets with kind proc-macro used to help build this library target.	List of labels	optional	[]
rustc_env	Dictionary of additional “key”: “value” environment variables to set for rustc. rust_test()/rust_binary() rules can use $(rootpath //package:target) to pass in the location of a generated file or external tool. Cargo build scripts that wish to expand locations should use cargo_build_script()'s build_script_env argument instead, as build scripts are run in a different environment - see cargo_build_script()'s documentation for more.	Dictionary: String -> String	optional	{}
rustc_env_files	Files containing additional environment variables to set for rustc. These files should contain a single variable per line, of format NAME=value, and newlines may be included in a value by ending a line with a trailing back-slash (\). The order that these files will be processed is unspecified, so multiple definitions of a particular variable are discouraged. Note that the variables here are subject to workspace status stamping should the stamp attribute be enabled. Stamp variables should be wrapped in brackets in order to be resolved. E.g. NAME={WORKSPACE_STATUS_VARIABLE}.	List of labels	optional	[]
rustc_flags	List of compiler flags passed to rustc. These strings are subject to Make variable expansion for predefined source/output path variables like $location, $execpath, and $rootpath. This expansion is useful if you wish to pass a generated file of arguments to rustc: @$(location //package:target).	List of strings	optional	[]
srcs	List of Rust .rs source files used to build the library. If srcs contains more than one file, then there must be a file either named lib.rs. Otherwise, crate_root must be set to the source file that is the root of the crate to be passed to rustc to build this crate.	List of labels	optional	[]
stamp	Whether to encode build information into the Rustc action. Possible values: - stamp = 1: Always stamp the build information into the Rustc action, even in --nostamp builds. This setting should be avoided, since it potentially kills remote caching for the target and any downstream actions that depend on it. - stamp = 0: Always replace build information by constant values. This gives good build result caching. - stamp = -1: Embedding of build information is controlled by the --[no]stamp flag. Stamped targets are not rebuilt unless their dependencies change. For example if a rust_library is stamped, and a rust_binary depends on that library, the stamped library won't be rebuilt when we change sources of the rust_binary. This is different from how cc_library.linkstamps behaves.	Integer	optional	0
version	A version to inject in the cargo environment variable.	String	optional	“0.0.0”

rust_proc_macro

Builds a Rust proc-macro crate.

ATTRIBUTES

Name	Description	Type	Mandatory	Default
name	A unique name for this target.	Name	required
aliases	Remap crates to a new name or moniker for linkage to this target These are other rust_library targets and will be presented as the new name given.	Dictionary: Label -> String	optional	{}
compile_data	List of files used by this rule at compile time. This attribute can be used to specify any data files that are embedded into the library, such as via the include_str! macro.	List of labels	optional	[]
crate_features	List of features to enable for this crate. Features are defined in the code using the #[cfg(feature = “foo”)] configuration option. The features listed here will be passed to rustc with --cfg feature=“${feature_name}” flags.	List of strings	optional	[]
crate_name	Crate name to use for this target. This must be a valid Rust identifier, i.e. it may contain only alphanumeric characters and underscores. Defaults to the target name, with any hyphens replaced by underscores.	String	optional	""
crate_root	The file that will be passed to rustc to be used for building this crate. If crate_root is not set, then this rule will look for a lib.rs file (or main.rs for rust_binary) or the single file in srcs if srcs contains only one file.	Label	optional	None
data	List of files used by this rule at compile time and runtime. If including data at compile time with include_str!() and similar, prefer compile_data over data, to prevent the data also being included in the runfiles.	List of labels	optional	[]
deps	List of other libraries to be linked to this library target. These can be either other rust_library targets or cc_library targets if linking a native library.	List of labels	optional	[]
edition	The rust edition to use for this crate. Defaults to the edition specified in the rust_toolchain.	String	optional	""
proc_macro_deps	List of rust_library targets with kind proc-macro used to help build this library target.	List of labels	optional	[]
rustc_env	Dictionary of additional “key”: “value” environment variables to set for rustc. rust_test()/rust_binary() rules can use $(rootpath //package:target) to pass in the location of a generated file or external tool. Cargo build scripts that wish to expand locations should use cargo_build_script()'s build_script_env argument instead, as build scripts are run in a different environment - see cargo_build_script()'s documentation for more.	Dictionary: String -> String	optional	{}
rustc_env_files	Files containing additional environment variables to set for rustc. These files should contain a single variable per line, of format NAME=value, and newlines may be included in a value by ending a line with a trailing back-slash (\). The order that these files will be processed is unspecified, so multiple definitions of a particular variable are discouraged. Note that the variables here are subject to workspace status stamping should the stamp attribute be enabled. Stamp variables should be wrapped in brackets in order to be resolved. E.g. NAME={WORKSPACE_STATUS_VARIABLE}.	List of labels	optional	[]
rustc_flags	List of compiler flags passed to rustc. These strings are subject to Make variable expansion for predefined source/output path variables like $location, $execpath, and $rootpath. This expansion is useful if you wish to pass a generated file of arguments to rustc: @$(location //package:target).	List of strings	optional	[]
srcs	List of Rust .rs source files used to build the library. If srcs contains more than one file, then there must be a file either named lib.rs. Otherwise, crate_root must be set to the source file that is the root of the crate to be passed to rustc to build this crate.	List of labels	optional	[]
stamp	Whether to encode build information into the Rustc action. Possible values: - stamp = 1: Always stamp the build information into the Rustc action, even in --nostamp builds. This setting should be avoided, since it potentially kills remote caching for the target and any downstream actions that depend on it. - stamp = 0: Always replace build information by constant values. This gives good build result caching. - stamp = -1: Embedding of build information is controlled by the --[no]stamp flag. Stamped targets are not rebuilt unless their dependencies change. For example if a rust_library is stamped, and a rust_binary depends on that library, the stamped library won't be rebuilt when we change sources of the rust_binary. This is different from how cc_library.linkstamps behaves.	Integer	optional	0
version	A version to inject in the cargo environment variable.	String	optional	“0.0.0”

rust_shared_library

Builds a Rust shared library.

This shared library will contain all transitively reachable crates and native objects. It is meant to be used when producing an artifact that is then consumed by some other build system (for example to produce a shared library that Python program links against).

This rule provides CcInfo, so it can be used everywhere Bazel expects rules_cc.

When building the whole binary in Bazel, use rust_library instead.

ATTRIBUTES

Name	Description	Type	Mandatory	Default
name	A unique name for this target.	Name	required
aliases	Remap crates to a new name or moniker for linkage to this target These are other rust_library targets and will be presented as the new name given.	Dictionary: Label -> String	optional	{}
compile_data	List of files used by this rule at compile time. This attribute can be used to specify any data files that are embedded into the library, such as via the include_str! macro.	List of labels	optional	[]
crate_features	List of features to enable for this crate. Features are defined in the code using the #[cfg(feature = “foo”)] configuration option. The features listed here will be passed to rustc with --cfg feature=“${feature_name}” flags.	List of strings	optional	[]
crate_name	Crate name to use for this target. This must be a valid Rust identifier, i.e. it may contain only alphanumeric characters and underscores. Defaults to the target name, with any hyphens replaced by underscores.	String	optional	""
crate_root	The file that will be passed to rustc to be used for building this crate. If crate_root is not set, then this rule will look for a lib.rs file (or main.rs for rust_binary) or the single file in srcs if srcs contains only one file.	Label	optional	None
data	List of files used by this rule at compile time and runtime. If including data at compile time with include_str!() and similar, prefer compile_data over data, to prevent the data also being included in the runfiles.	List of labels	optional	[]
deps	List of other libraries to be linked to this library target. These can be either other rust_library targets or cc_library targets if linking a native library.	List of labels	optional	[]
edition	The rust edition to use for this crate. Defaults to the edition specified in the rust_toolchain.	String	optional	""
proc_macro_deps	List of rust_library targets with kind proc-macro used to help build this library target.	List of labels	optional	[]
rustc_env	Dictionary of additional “key”: “value” environment variables to set for rustc. rust_test()/rust_binary() rules can use $(rootpath //package:target) to pass in the location of a generated file or external tool. Cargo build scripts that wish to expand locations should use cargo_build_script()'s build_script_env argument instead, as build scripts are run in a different environment - see cargo_build_script()'s documentation for more.	Dictionary: String -> String	optional	{}
rustc_env_files	Files containing additional environment variables to set for rustc. These files should contain a single variable per line, of format NAME=value, and newlines may be included in a value by ending a line with a trailing back-slash (\). The order that these files will be processed is unspecified, so multiple definitions of a particular variable are discouraged. Note that the variables here are subject to workspace status stamping should the stamp attribute be enabled. Stamp variables should be wrapped in brackets in order to be resolved. E.g. NAME={WORKSPACE_STATUS_VARIABLE}.	List of labels	optional	[]
rustc_flags	List of compiler flags passed to rustc. These strings are subject to Make variable expansion for predefined source/output path variables like $location, $execpath, and $rootpath. This expansion is useful if you wish to pass a generated file of arguments to rustc: @$(location //package:target).	List of strings	optional	[]
srcs	List of Rust .rs source files used to build the library. If srcs contains more than one file, then there must be a file either named lib.rs. Otherwise, crate_root must be set to the source file that is the root of the crate to be passed to rustc to build this crate.	List of labels	optional	[]
stamp	Whether to encode build information into the Rustc action. Possible values: - stamp = 1: Always stamp the build information into the Rustc action, even in --nostamp builds. This setting should be avoided, since it potentially kills remote caching for the target and any downstream actions that depend on it. - stamp = 0: Always replace build information by constant values. This gives good build result caching. - stamp = -1: Embedding of build information is controlled by the --[no]stamp flag. Stamped targets are not rebuilt unless their dependencies change. For example if a rust_library is stamped, and a rust_binary depends on that library, the stamped library won't be rebuilt when we change sources of the rust_binary. This is different from how cc_library.linkstamps behaves.	Integer	optional	0
version	A version to inject in the cargo environment variable.	String	optional	“0.0.0”

rust_static_library

Builds a Rust static library.

This static library will contain all transitively reachable crates and native objects. It is meant to be used when producing an artifact that is then consumed by some other build system (for example to produce an archive that Python program links against).

This rule provides CcInfo, so it can be used everywhere Bazel expects rules_cc.

When building the whole binary in Bazel, use rust_library instead.

ATTRIBUTES

Name	Description	Type	Mandatory	Default
name	A unique name for this target.	Name	required
aliases	Remap crates to a new name or moniker for linkage to this target These are other rust_library targets and will be presented as the new name given.	Dictionary: Label -> String	optional	{}
compile_data	List of files used by this rule at compile time. This attribute can be used to specify any data files that are embedded into the library, such as via the include_str! macro.	List of labels	optional	[]
crate_features	List of features to enable for this crate. Features are defined in the code using the #[cfg(feature = “foo”)] configuration option. The features listed here will be passed to rustc with --cfg feature=“${feature_name}” flags.	List of strings	optional	[]
crate_name	Crate name to use for this target. This must be a valid Rust identifier, i.e. it may contain only alphanumeric characters and underscores. Defaults to the target name, with any hyphens replaced by underscores.	String	optional	""
crate_root	The file that will be passed to rustc to be used for building this crate. If crate_root is not set, then this rule will look for a lib.rs file (or main.rs for rust_binary) or the single file in srcs if srcs contains only one file.	Label	optional	None
data	List of files used by this rule at compile time and runtime. If including data at compile time with include_str!() and similar, prefer compile_data over data, to prevent the data also being included in the runfiles.	List of labels	optional	[]
deps	List of other libraries to be linked to this library target. These can be either other rust_library targets or cc_library targets if linking a native library.	List of labels	optional	[]
edition	The rust edition to use for this crate. Defaults to the edition specified in the rust_toolchain.	String	optional	""
proc_macro_deps	List of rust_library targets with kind proc-macro used to help build this library target.	List of labels	optional	[]
rustc_env	Dictionary of additional “key”: “value” environment variables to set for rustc. rust_test()/rust_binary() rules can use $(rootpath //package:target) to pass in the location of a generated file or external tool. Cargo build scripts that wish to expand locations should use cargo_build_script()'s build_script_env argument instead, as build scripts are run in a different environment - see cargo_build_script()'s documentation for more.	Dictionary: String -> String	optional	{}
rustc_env_files	Files containing additional environment variables to set for rustc. These files should contain a single variable per line, of format NAME=value, and newlines may be included in a value by ending a line with a trailing back-slash (\). The order that these files will be processed is unspecified, so multiple definitions of a particular variable are discouraged. Note that the variables here are subject to workspace status stamping should the stamp attribute be enabled. Stamp variables should be wrapped in brackets in order to be resolved. E.g. NAME={WORKSPACE_STATUS_VARIABLE}.	List of labels	optional	[]
rustc_flags	List of compiler flags passed to rustc. These strings are subject to Make variable expansion for predefined source/output path variables like $location, $execpath, and $rootpath. This expansion is useful if you wish to pass a generated file of arguments to rustc: @$(location //package:target).	List of strings	optional	[]
srcs	List of Rust .rs source files used to build the library. If srcs contains more than one file, then there must be a file either named lib.rs. Otherwise, crate_root must be set to the source file that is the root of the crate to be passed to rustc to build this crate.	List of labels	optional	[]
stamp	Whether to encode build information into the Rustc action. Possible values: - stamp = 1: Always stamp the build information into the Rustc action, even in --nostamp builds. This setting should be avoided, since it potentially kills remote caching for the target and any downstream actions that depend on it. - stamp = 0: Always replace build information by constant values. This gives good build result caching. - stamp = -1: Embedding of build information is controlled by the --[no]stamp flag. Stamped targets are not rebuilt unless their dependencies change. For example if a rust_library is stamped, and a rust_binary depends on that library, the stamped library won't be rebuilt when we change sources of the rust_binary. This is different from how cc_library.linkstamps behaves.	Integer	optional	0
version	A version to inject in the cargo environment variable.	String	optional	“0.0.0”

rust_test

Builds a Rust test crate.

Examples:

Suppose you have the following directory structure for a Rust library crate with unit test code in the library sources:

[workspace]/
    WORKSPACE
    hello_lib/
        BUILD
        src/
            lib.rs

hello_lib/src/lib.rs:

pub struct Greeter {
    greeting: String,
}

impl Greeter {
    pub fn new(greeting: &str) -> Greeter {
        Greeter { greeting: greeting.to_string(), }
    }

    pub fn greet(&self, thing: &str) -> String {
        format!("{} {}", &self.greeting, thing)
    }
}

#[cfg(test)]
mod test {
    use super::Greeter;

    #[test]
    fn test_greeting() {
        let hello = Greeter::new("Hi");
        assert_eq!("Hi Rust", hello.greet("Rust"));
    }
}

To build and run the tests, simply add a rust_test rule with no srcs and only depends on the hello_lib rust_library target via the crate attribute:

hello_lib/BUILD:

load("@rules_rust//rust:defs.bzl", "rust_library", "rust_test")

rust_library(
    name = "hello_lib",
    srcs = ["src/lib.rs"],
)

rust_test(
    name = "hello_lib_test",
    crate = ":hello_lib",
    # You may add other deps that are specific to the test configuration
    deps = ["//some/dev/dep"],

Run the test with bazel test //hello_lib:hello_lib_test. The crate will be built using the same crate name as the underlying “:hello_lib” crate.

Example: test directory

Integration tests that live in the tests directory, they are essentially built as separate crates. Suppose you have the following directory structure where greeting.rs is an integration test for the hello_lib library crate:

[workspace]/
    WORKSPACE
    hello_lib/
        BUILD
        src/
            lib.rs
        tests/
            greeting.rs

hello_lib/tests/greeting.rs:

extern crate hello_lib;

use hello_lib;

#[test]
fn test_greeting() {
    let hello = greeter::Greeter::new("Hello");
    assert_eq!("Hello world", hello.greeting("world"));
}

To build the greeting.rs integration test, simply add a rust_test target with greeting.rs in srcs and a dependency on the hello_lib target:

hello_lib/BUILD:

load("@rules_rust//rust:defs.bzl", "rust_library", "rust_test")

rust_library(
    name = "hello_lib",
    srcs = ["src/lib.rs"],
)

rust_test(
    name = "greeting_test",
    srcs = ["tests/greeting.rs"],
    deps = [":hello_lib"],
)

Run the test with bazel test //hello_lib:greeting_test.

ATTRIBUTES

Name	Description	Type	Mandatory	Default
name	A unique name for this target.	Name	required
aliases	Remap crates to a new name or moniker for linkage to this target These are other rust_library targets and will be presented as the new name given.	Dictionary: Label -> String	optional	{}
compile_data	List of files used by this rule at compile time. This attribute can be used to specify any data files that are embedded into the library, such as via the include_str! macro.	List of labels	optional	[]
crate	Target inline tests declared in the given crate These tests are typically those that would be held out under #[cfg(test)] declarations.	Label	optional	None
crate_features	List of features to enable for this crate. Features are defined in the code using the #[cfg(feature = “foo”)] configuration option. The features listed here will be passed to rustc with --cfg feature=“${feature_name}” flags.	List of strings	optional	[]
crate_name	Crate name to use for this target. This must be a valid Rust identifier, i.e. it may contain only alphanumeric characters and underscores. Defaults to the target name, with any hyphens replaced by underscores.	String	optional	""
crate_root	The file that will be passed to rustc to be used for building this crate. If crate_root is not set, then this rule will look for a lib.rs file (or main.rs for rust_binary) or the single file in srcs if srcs contains only one file.	Label	optional	None
data	List of files used by this rule at compile time and runtime. If including data at compile time with include_str!() and similar, prefer compile_data over data, to prevent the data also being included in the runfiles.	List of labels	optional	[]
deps	List of other libraries to be linked to this library target. These can be either other rust_library targets or cc_library targets if linking a native library.	List of labels	optional	[]
edition	The rust edition to use for this crate. Defaults to the edition specified in the rust_toolchain.	String	optional	""
env	Specifies additional environment variables to set when the test is executed by bazel test. Values are subject to $(rootpath), $(execpath), location, and “Make variable” substitution. Execpath returns absolute path, and in order to be able to construct the absolute path we need to wrap the test binary in a launcher. Using a launcher comes with complications, such as more complicated debugger attachment.	Dictionary: String -> String	optional	{}
experimental_use_cc_common_link	Whether to use cc_common.link to link rust binaries. Possible values: [-1, 0, 1]. -1 means use the value of the toolchain.experimental_use_cc_common_link boolean build setting to determine. 0 means do not use cc_common.link (use rustc instead). 1 means use cc_common.link.	Integer	optional	-1
proc_macro_deps	List of rust_library targets with kind proc-macro used to help build this library target.	List of labels	optional	[]
rustc_env	Dictionary of additional “key”: “value” environment variables to set for rustc. rust_test()/rust_binary() rules can use $(rootpath //package:target) to pass in the location of a generated file or external tool. Cargo build scripts that wish to expand locations should use cargo_build_script()'s build_script_env argument instead, as build scripts are run in a different environment - see cargo_build_script()'s documentation for more.	Dictionary: String -> String	optional	{}
rustc_env_files	Files containing additional environment variables to set for rustc. These files should contain a single variable per line, of format NAME=value, and newlines may be included in a value by ending a line with a trailing back-slash (\). The order that these files will be processed is unspecified, so multiple definitions of a particular variable are discouraged. Note that the variables here are subject to workspace status stamping should the stamp attribute be enabled. Stamp variables should be wrapped in brackets in order to be resolved. E.g. NAME={WORKSPACE_STATUS_VARIABLE}.	List of labels	optional	[]
rustc_flags	List of compiler flags passed to rustc. These strings are subject to Make variable expansion for predefined source/output path variables like $location, $execpath, and $rootpath. This expansion is useful if you wish to pass a generated file of arguments to rustc: @$(location //package:target).	List of strings	optional	[]
srcs	List of Rust .rs source files used to build the library. If srcs contains more than one file, then there must be a file either named lib.rs. Otherwise, crate_root must be set to the source file that is the root of the crate to be passed to rustc to build this crate.	List of labels	optional	[]
stamp	Whether to encode build information into the Rustc action. Possible values: - stamp = 1: Always stamp the build information into the Rustc action, even in --nostamp builds. This setting should be avoided, since it potentially kills remote caching for the target and any downstream actions that depend on it. - stamp = 0: Always replace build information by constant values. This gives good build result caching. - stamp = -1: Embedding of build information is controlled by the --[no]stamp flag. Stamped targets are not rebuilt unless their dependencies change. For example if a rust_library is stamped, and a rust_binary depends on that library, the stamped library won't be rebuilt when we change sources of the rust_binary. This is different from how cc_library.linkstamps behaves.	Integer	optional	0
use_libtest_harness	Whether to use libtest. For targets using this flag, individual tests can be run by using the --test_arg flag. E.g. bazel test //src:rust_test --test_arg=foo::test::test_fn.	Boolean	optional	True
version	A version to inject in the cargo environment variable.	String	optional	“0.0.0”

rust_test_suite

A rule for creating a test suite for a set of rust_test targets.

This rule can be used for setting up typical rust integration tests. Given the following directory structure:

[crate]/
    BUILD.bazel
    src/
        lib.rs
        main.rs
    tests/
        integrated_test_a.rs
        integrated_test_b.rs
        integrated_test_c.rs
        patterns/
            fibonacci_test.rs

The rule can be used to generate rust_test targets for each source file under tests and a test_suite which encapsulates all tests.

load("//rust:defs.bzl", "rust_binary", "rust_library", "rust_test_suite")

rust_library(
    name = "math_lib",
    srcs = ["src/lib.rs"],
)

rust_binary(
    name = "math_bin",
    srcs = ["src/main.rs"],
)

rust_test_suite(
    name = "integrated_tests_suite",
    srcs = glob(["tests/**"]),
    deps = [":math_lib"],
)

PARAMETERS

Name	Description	Default Value
name	The name of the test_suite.	none
srcs	All test sources, typically glob([“tests/**/*.rs”]).	none
kwargs	Additional keyword arguments for the underyling rust_test targets. The tags argument is also passed to the generated test_suite target.	none