pw_unit_test#

GoogleTest for embedded

Stable

mylib_test.cpp

#include "mylib.h"
#include "pw_unit_test/framework.h"

namespace {

TEST(MyTestSuite, MyTestCase) {
  pw::InlineString<32> expected = "(╯°□°)╯︵ ┻━┻";
  pw::InlineString<32> actual = mylib::flip_table();
  EXPECT_STREQ(expected.c_str(), actual.c_str());
}

}  // namespace

BUILD.bazel

load("@pigweed//pw_unit_test:pw_cc_test.bzl", "pw_cc_test")

cc_library(
    name = "mylib",
    srcs = ["mylib.cc"],
    hdrs = ["mylib.h"],
    includes = ["."],
    deps = ["@pigweed//pw_string"],
)

pw_cc_test(
    name = "mylib_test",
    srcs = ["mylib_test.cc"],
    deps = [
        "@pigweed//pw_unit_test",
        ":mylib",
    ],
)

mylib.cc

#include "mylib.h"
#include "pw_string/string.h"

namespace mylib {

pw::InlineString<32> flip_table() {
  pw::InlineString<32> textmoji = "(╯°□°)╯︵ ┻━┻";
  return textmoji;
}

}  // namespace mylib

mylib.h

#include "pw_string/string.h"

namespace mylib {

pw::InlineString<32> flip_table();

}

pw_unit_test provides a GoogleTest-compatible unit testing framework for Pigweed-based projects. The default backend is a lightweight subset of GoogleTest that uses embedded-friendly primitives.

Quickstart

Set up your project for testing and learn testing basics.

Guides

Learn how to do common tasks.

C++ API reference

Get detailed C++ API reference information.

Bazel API reference

Get detailed Bazel API reference information.

GN API reference

Get detailed GN API reference information.

CMake API reference

Get detailed CMake API reference information.

Python API reference

Get detailed Python API reference information.

Quickstart#

Set up your build system#

Bazel

Load the pw_cc_test rule and create a target that depends on @pigweed//pw_unit_test as well as the code you want to test:

load("@pigweed//pw_unit_test:pw_cc_test.bzl", "pw_cc_test")

cc_library(
    name = "mylib",
    srcs = ["mylib.cc"],
    hdrs = ["mylib.h"],
    includes = ["."],
    deps = ["..."],
)

pw_cc_test(
    name = "mylib_test",
    srcs = ["mylib_test.cc"],
    deps = [
        "@pigweed//pw_unit_test",
        ":mylib",
    ],
)

Write tests#

Create test suites and test cases:

#include "mylib.h"
#include "pw_unit_test/framework.h"

namespace {

TEST(MyTestSuite, MyTestCase) {
  pw::InlineString<32> expected = "(╯°□°)╯︵ ┻━┻";
  pw::InlineString<32> actual = app::flip_table();
  EXPECT_STREQ(expected.c_str(), actual.c_str());
}

}  // namespace

pw_unit_test provides a standard set of TEST, EXPECT, ASSERT and FAIL macros. The default backend, pw_unit_test:light, offers an embedded-friendly implementation which prioritizes small code size.

Alternativley, users can opt into a larger set of assertion macros, matchers, and more detailed error messages by using the pw_unit_test:googletest backend. See Choose a backend.

See GoogleTest Primer for the basics of using GoogleTest.

Run tests#

Bazel

$ bazel test //src:mylib_test

Run the generated test binary:

$ ./out/.../mylib_test

Guides#

Choose a backend#

The default backend, pw_unit_test:light, is a lightweight subset of GoogleTest that uses embedded-friendly primitives. It’s also highly portable because it offloads the responsibility of test reporting and output to the underlying system, communicating its results through a common interface. This lets you write unit tests once and run them under many different environments.

If the subset of GoogleTest that pw_unit_test:light supports doesn’t meet your needs, you can access the full upstream GoogleTest API through pw_unit_test:googletest. See Use upstream GoogleTest.

`pw_unit_test:light` API compatibility#

pw_unit_test:light offers a number of primitives for test declaration, assertion, event handlers, and configuration.

Note

The googletest_test_matchers target which provides Pigweed-specific StatusIs, IsOkAndHolds isn’t part of the pw_unit_test:light backend. These matchers are only usable when including the full upstream GoogleTest backend.

Missing features include:

GoogleMock and matchers (e.g. EXPECT_THAT).
Death tests (e.g. EXPECT_DEATH). EXPECT_DEATH_IF_SUPPORTED does nothing but silently passes.
Value-parameterized tests.
Stream messages (e.g. EXPECT_TRUE(...) << "My message") will compile, but no message will be logged.
SCOPED_TRACE will compile, but trace information will not be added to failure messages.

See Use upstream GoogleTest for guidance on using the upstream GoogleTest backend (pw_unit_test:googletest) instead of pw_unit_test:light.

Create a custom `main` function#

For simple unit tests that run on host the workflow outlined in Quickstart is all you need. Pigweed’s build templates generate a simple main function to run the tests with.

To do more complex testing, such as on-device testing:

Create your own main function:

#include "pw_unit_test/framework.h"
// pw_unit_test:light requires an event handler to be configured.
#include "pw_unit_test/simple_printing_event_handler.h"

void WriteString(std::string_view string, bool newline) {
  printf("%s", string.data());
  if (newline) {
    printf("\n");
  }
}

int main() {
  // Make the binary compatible with pw_unit_test:googletest. Has no effect
  // when using pw_unit_test:light.
  testing::InitGoogleTest();
  // Set up the event handler for pw_unit_test:light.
  pw::unit_test::SimplePrintingEventHandler handler(WriteString);
  pw::unit_test::RegisterEventHandler(&handler);
  return RUN_ALL_TESTS();
}

See Create event handlers for more information about handling events.

Set the build argument that instructs your build system to use your custom main function:
- Bazel: @pigweed//pw_unit_test:main
- GN: pw_unit_test_MAIN

Create event handlers#

The pw::unit_test::EventHandler class defines the interface through which pw_unit_test:light communicates the results of its test runs. If you’re using a custom main function you need to register an event handler to receive test output from the framework.

Predefined event handlers#

Pigweed provides some standard event handlers to simplify the process of getting started with pw_unit_test:light. All event handlers provide for GoogleTest-style output using the shared GoogleTestStyleEventHandler base. Example output:

[==========] Running all tests.
[ RUN      ] Status.Default
[       OK ] Status.Default
[ RUN      ] Status.ConstructWithStatusCode
[       OK ] Status.ConstructWithStatusCode
[ RUN      ] Status.AssignFromStatusCode
[       OK ] Status.AssignFromStatusCode
[ RUN      ] Status.CompareToStatusCode
[       OK ] Status.CompareToStatusCode
[ RUN      ] Status.Ok_OkIsTrue
[       OK ] Status.Ok_OkIsTrue
[ RUN      ] Status.NotOk_OkIsFalse
[       OK ] Status.NotOk_OkIsFalse
[ RUN      ] Status.KnownString
[       OK ] Status.KnownString
[ RUN      ] Status.UnknownString
[       OK ] Status.UnknownString
[==========] Done running all tests.
[  PASSED  ] 8 test(s).

Run a subset of test suites#

To run only a subset of registered test suites, use the pw::unit_test::SetTestSuitesToRun function. See pw_unit_test/light_public_overrides/pw_unit_test/framework_backend.h.

This is useful when you’ve got a lot of test suites bundled up into a single test binary and you only need to run some of them.

Skip tests in Bazel#

Use target_compatible_with in Bazel to skip tests. The following test is skipped when using upstream GoogleTest:

load("//pw_unit_test:pw_cc_test.bzl", "pw_cc_test")

pw_cc_test(
    name = "no_upstream_test",
    srcs = ["no_upstream_test.cc"],
    target_compatible_with = select({
        "//pw_unit_test:backend_is_googletest": ["@platforms//:incompatible"],
        "//conditions:default": [],
    }),
)

Run tests in static libraries#

To run tests in a static library, use the PW_UNIT_TEST_LINK_FILE_CONTAINING_TEST macro.

Linkers usually ignore tests through static libraries (i.e. .a files) because test registration relies on the test instance’s static constructor adding itself to a global list of tests. When linking against a static library, static constructors in an object file are ignored unless at least one entity in that object file is linked.

Use upstream GoogleTest#

To use the upstream GoogleTest backend (pw_unit_test:googletest) instead of the default backend:

Clone the GoogleTest repository into your project. See GoogleTest.
Create a custom main function.

Combine GoogleTestHandlerAdapter with a predefined event handler to enable your main function to work with upstream GoogleTest without modification.

#include "pw_unit_test/framework.h"
#include "pw_unit_test/logging_event_handler.h"

int main() {
  testing::InitGoogleTest();
  pw::unit_test::LoggingEventHandler logger;
  pw::unit_test::RegisterEventHandler(&logger);
  return RUN_ALL_TESTS();
}

If your tests needs GoogleTest functionality not included in the default pw_unit_test:light backend, include the upstream GoogleTest headers (e.g. gtest/gtest.h) directly and guard your target definition to avoid compiling with pw_unit_test:light (the default backend).

Run tests over serial#

To accelerate automated unit test bringup for devices with plain-text logging, pw_unit_test provides a serial-based test runner in Python that triggers a device flash and evaluates whether the test passed or failed based on the produced output.

To set up a serial test runner in Python:

Implement a SerialTestingDevice class for your device. See pw_unit_test/py/pw_unit_test/serial_test_runner.py.
Configure your device code to wait to run unit tests until DEFAULT_TEST_START_CHARACTER is sent over the serial connection.

Run tests over RPC#

pw_unit_test provides an RPC service which runs unit tests on demand and streams the results back to the client. The service is defined in pw_unit_test/pw_unit_test_proto/unit_test.proto.

The RPC service is primarily intended for use with the default pw_unit_test:light backend. It has some support for the upstream GoogleTest backend (pw_unit_test:googletest), however some features (such as test suite filtering) are missing.

To set up RPC-based unit tests in your application:

Depend on the relevant target for your build system:
- Bazel: @pigweed//pw_unit_test:rpc_service
- GN: $dir_pw_unit_test:rpc_service
Initialize a pw::unit_test::UnitTestThread instance and define a pw::Thread using it as the entry point. (See example below.)

#include "pw_rpc/server.h"
#include "pw_thread/thread.h"
#include "pw_unit_test/unit_test_service.h"

pw::rpc::Channel channels[] = {
    pw::rpc::Channel::Create<1>(&my_output),
};
pw::rpc::Server server(channels);

constexpr pw::ThreadAttrs kUnitTestThreadAttrs =
    pw::ThreadAttrs()
        .set_name("UnitTestThread")
        .set_priority(pw::ThreadPriority::Medium())
        .set_stack_size_bytes(4096);
pw::ThreadContextFor<kUnitTestThreadAttrs> unit_test_thread_context;

pw::unit_test::UnitTestThread unit_test_thread;

void AppInit() {
  pw::Thread(pw::GetThreadOptions(unit_test_thread_context), unit_test_thread)
      .detach();
  server.RegisterService(unit_test_thread.service());
}

See pw_rpc for more guidance around setting up RPC.

Run tests that have been flashed to a device by calling pw_unit_test.rpc.run_tests() in Python. The argument should be an RPC client services object that has the unit testing RPC service enabled. By default, the results output via logging. The return value is a TestRecord dataclass instance containing the results of the test run.

import serial

from pw_hdlc import rpc
from pw_unit_test.rpc import run_tests

PROTO = Path(
    os.environ['PW_ROOT'],
    'pw_unit_test/pw_unit_test_proto/unit_test.proto'
)
serial_device = serial.Serial(device, baud)
with rpc.SerialReader(serial_device) as reader:
    with rpc.HdlcRpcClient(
        reader, PROTO, rpc.default_channels(serial_device.write)
    ) as client:
        run_tests(client.rpcs())

Golden file testing with `pw_golden_test`#

The pw_golden_test macro in //pw_unit_test/golden.bzl defines tests that execute a binary and compares its output against the contents of a predefined “golden” file. This is useful for testing that command-line tools or other binaries run successfully and produce consistent text-based output across code changes.

If the output of the binary differs from the expected file, the test prints a diff between the actual and expected outputs and exits with a non-zero code.

The following example shows how to use pw_golden_test in Bazel. The test runs the //pw_unit_test:run_and_compare_test_executable C++ binary and compares its output to the run_and_compare_test.expected file.

pw_golden_test(
    name = "run_and_compare_test",
    args = [
        "--extra",
        "args",
    ],
    executable = "//pw_unit_test:run_and_compare_test_executable",
    expected = ":run_and_compare_test.expected",
)

In GN and CMake, directly run the //pw_unit_test/py/pw_unit_test/golden_test.py script for golden tests.

C++ API reference#

Moved: pw_unit_test

Python API reference#

`pw_unit_test.serial_test_runner`#

Facilitates automating unit tests on devices with serial ports.

This library assumes that the on-device test runner emits the test results as plain-text over a serial port, and that tests are triggered by a pre-defined input (DEFAULT_TEST_START_CHARACTER) over the same serial port that results are emitted from.

class pw_unit_test.serial_test_runner.SerialTestingDevice#

A device that supports automated testing via parsing serial output.

abstract baud_rate() → int#

Returns the baud rate to use when connecting to this device.

Raises:: DeviceNotFound – This device is no longer available.

abstract load_binary(binary: Path) → bool#

Flashes the specified binary to this device.

Raises:

DeviceNotFound – This device is no longer available.
FlashingFailure – The binary could not be flashed.

Returns:

True if the binary was loaded successfully.

abstract serial_port() → str#

Returns the name of the com port this device is enumerated on.

Raises:: DeviceNotFound – This device is no longer available.

pw_unit_test.serial_test_runner.run_device_test( device: ~pw_unit_test.serial_test_runner.SerialTestingDevice, binary: ~pathlib.Path, test_timeout: float, logger: ~logging.Logger = <Logger serial_test_runner (WARNING)>, ) → bool#

Runs tests on a device.

When a unit test run fails, results are logged as an error.

Parameters:

device – The device to run tests on.
binary – The binary containing tests to flash on the device.
test_timeout – If the device stops producing output longer than this timeout, the test is considered stuck and is aborted.

Returns:

True if all tests passed.

`pw_unit_test.rpc`#

Utilities for running unit tests over pw_rpc.

class pw_unit_test.rpc.EventHandler#

abstract run_all_tests_end(passed_tests: int, failed_tests: int) → None#: Called after the test run is complete.

abstract run_all_tests_start() → None#: Called before all tests are run.

abstract test_case_disabled(test_case: TestCase) → None#: Called when a disabled test case is encountered.

abstract test_case_end(test_case: TestCase, result: TestCaseResult) → None#: Called when a test case completes with its overall result.

abstract test_case_expect(test_case: TestCase, expectation: TestExpectation) → None#: Called after each expect or assert statement within a test case.

abstract test_case_start(test_case: TestCase) → None#: Called when a new test case is started.

class pw_unit_test.rpc.TestRecord( passing_tests: tuple[TestCase, ...], failing_tests: tuple[TestCase, ...], disabled_tests: tuple[TestCase, ...], )#

Records test results.

__init__( passing_tests: tuple[TestCase, ...], failing_tests: tuple[TestCase, ...], disabled_tests: tuple[TestCase, ...], ) → None#

pw_unit_test.rpc.run_tests( rpcs: ~pw_rpc.client.Services, report_passed_expectations: bool = False, test_suites: ~typing.Iterable[str] = (), event_handlers: ~typing.Iterable[~pw_unit_test.rpc.EventHandler] = (<pw_unit_test.rpc.LoggingEventHandler object>, ), timeout_s: ~pw_rpc.callback_client.call.UseDefault | float | None = UseDefault.VALUE, ) → TestRecord#

Runs unit tests on a device over pw_rpc.

Calls each of the provided event handlers as test events occur, and returns True if all tests pass.

Build helper libraries#

The following helper libraries can simplify setup and are supported in all build systems.

simple_printing_event_handler: When running tests, output test results as plain text over pw_sys_io.

simple_printing_main: Implements a main() function that simply runs tests using the simple_printing_event_handler.

logging_event_handler: When running tests, log test results as plain text using pw_log. Make sure your target has set a pw_log backend.

logging_main: Implements a main() function that simply runs tests using the logging_event_handler.

Bazel API reference#

`pw_cc_test`#

pw_cc_test is a wrapper for cc_test that provides some defaults, such as a dependency on @pigweed//pw_unit_test:main. It supports and passes through all the arguments recognized by cc_test.

Label flags#

@pigweed//pw_unit_test:backend#

The GoogleTest implementation to use for Pigweed unit tests. This library provides gtest/gtest.h and related headers. Defaults to @pigweed//pw_unit_test:light, which implements a subset of GoogleTest.

Type: Bazel target label

Usage: Typically specified as part of the platform definition, but can also be set manually on the command line.

@pigweed//pw_unit_test:main#

Implementation of a main function for pw_cc_test unit test binaries. To use upstream GoogleTest, set this to @com_google_googletest//:gtest_main. Note that this may not work on most embedded devices, see b/310957361.

Type: Bazel target label

Usage: Typically specified as part of the platform definition, but can also be set manually on the command line.

GN reference#

`pw_test`#

pw_test defines a single unit test suite.

Targets#

<target_name>: The test suite within a single binary. The test code is linked against the target set in the build arg pw_unit_test_MAIN.

<target_name>.run: If pw_unit_test_AUTOMATIC_RUNNER is set, this target runs the test as part of the build.

<target_name>.lib: The test sources without pw_unit_test_MAIN.

Arguments#

All GN executable arguments are accepted and forwarded to the underlying pw_executable.

enable_if#: Boolean indicating whether the test should be built. If false, replaces the test with an empty target. Default true.

source_gen_deps#: List of target labels that generate source files used by this test. The labels must meet the constraints of GN’s get_target_outputs, namely they must have been previously defined in the current file. This argument is required if a test uses generated source files and enable_if can evaluate to false.

test_main#: Target label to add to the tests’s dependencies to provide the main() function. Defaults to pw_unit_test_MAIN. Set to "" if main() is implemented in the test’s sources.

test_automatic_runner_args#: Array of args to pass to automatic test runner. Defaults to pw_unit_test_AUTOMATIC_RUNNER_ARGS.

envvars#: Array of key=value strings representing environment variables to set when invoking the automatic test runner.

Example#

import("$dir_pw_unit_test/test.gni")

pw_test("large_test") {
  sources = [ "large_test.cc" ]
  enable_if = device_has_1m_flash
}

`pw_test_group`#

pw_test_group defines a collection of tests or other test groups.

Targets#

<target_name>: The test group itself.

<target_name>.run: If pw_unit_test_AUTOMATIC_RUNNER is set, this target runs all of the tests in the group and all of its group dependencies individually. See Run tests over serial.

<target_name>.lib: The sources of all of the tests in this group and their dependencies.

<target_name>.bundle: All of the tests in the group and its dependencies bundled into a single binary.

<target_name>.bundle.run: Automatic runner for the test bundle.

Arguments#

tests#: List of the pw_test targets in the group.

group_deps#: List of other pw_test_group targets on which this one depends.

enable_if#: Boolean indicating whether the group target should be created. If false, an empty GN group is created instead. Default true.

Example#

import("$dir_pw_unit_test/test.gni")

pw_test_group("tests") {
  tests = [
    ":bar_test",
    ":foo_test",
  ]
}

pw_test("foo_test") {
  # ...
}

pw_test("bar_test") {
  # ...
}

`pw_facade_test`#

Pigweed facade test templates allow individual unit tests to build under the current device target configuration while overriding specific build arguments. This allows these tests to replace a facade’s backend for the purpose of testing the facade layer.

Facade tests are disabled by default. To build and run facade tests, set the GN arg pw_unit_test_FACADE_TESTS_ENABLED to true.

Warning

Facade tests are costly because each facade test will trigger a re-build of every dependency of the test. While this sounds excessive, it’s the only technically correct way to handle this type of test.

Warning

Some facade test configurations may not be compatible with your target. Be careful when running a facade test on a system that heavily depends on the facade being tested.

GN build arguments#

pw_unit_test_BACKEND <source_set>#

The GoogleTest implementation to use for Pigweed unit tests. This library provides gtest/gtest.h and related headers. Defaults to pw_unit_test:light, which implements a subset of GoogleTest.

Type: string (GN path to a source set)

Usage: toolchain-controlled only

pw_unit_test_MAIN <source_set>#

Implementation of a main function for pw_test unit test binaries. See Create a custom main function.

Type: string (GN path to a source set)

Usage: toolchain-controlled only

pw_unit_test_AUTOMATIC_RUNNER <executable>#

Path to a test runner to automatically run unit tests after they are built. See Run tests over serial.

If set, a pw_test target’s <target_name>.run action invokes the test runner specified by this argument, passing the path to the unit test to run. If this is unset, the pw_test target’s <target_name>.run step will do nothing.

Targets that don’t support parallelized execution of tests (e.g. an on-device test runner that must flash a device and run the test in serial) should set pw_unit_test_POOL_DEPTH to 1.

Type: string (name of an executable on PATH, or a path to an executable)

Usage: toolchain-controlled only

pw_unit_test_AUTOMATIC_RUNNER_ARGS <args>#

An optional list of strings to pass as args to the test runner specified by pw_unit_test_AUTOMATIC_RUNNER.

Type: list of strings (args to pass to pw_unit_test_AUTOMATIC_RUNNER)

Usage: toolchain-controlled only

pw_unit_test_AUTOMATIC_RUNNER_TIMEOUT <timeout_seconds>#

An optional timeout to apply when running the automatic runner. Timeout is in seconds. Defaults to empty which means no timeout.

Type: string (number of seconds to wait before killing test runner)

Usage: toolchain-controlled only

pw_unit_test_POOL_DEPTH <pool_depth>#

The maximum number of unit tests that may be run concurrently for the current toolchain. Setting this to 0 disables usage of a pool, allowing unlimited parallelization.

Note: A single target with two toolchain configurations (e.g. release and debug) uses two separate test runner pools by default. Set pw_unit_test_POOL_TOOLCHAIN to the same toolchain for both targets to merge the pools and force serialization.

Type: integer

Usage: toolchain-controlled only

pw_unit_test_POOL_TOOLCHAIN <toolchain>#

The toolchain to use when referring to the pw_unit_test runner pool. When this is disabled, the current toolchain is used. This means that every toolchain will use its own pool definition. If two toolchains should share the same pool, this argument should be by one of the toolchains to the GN path of the other toolchain.

Type: string (GN path to a toolchain)

Usage: toolchain-controlled only

pw_unit_test_EXECUTABLE_TARGET_TYPE <template name>#

The name of the GN target type used to build pw_unit_test executables.

Type: string (name of a GN template)

Usage: toolchain-controlled only

pw_unit_test_EXECUTABLE_TARGET_TYPE_FILE <gni file path>#

The path to the .gni file that defines pw_unit_test_EXECUTABLE_TARGET_TYPE.

If pw_unit_test_EXECUTABLE_TARGET_TYPE is not the default of pw_executable, this .gni file is imported to provide the template definition.

Type: string (path to a .gni file)

Usage: toolchain-controlled only

pw_unit_test_FACADE_TESTS_ENABLED <boolean>#: Controls whether to build and run facade tests. Facade tests add considerably to build time, so they are disabled by default.

pw_unit_test_TESTONLY <boolean>#: Controls the testonly variable in pw_test, pw_test_group, and miscellaneous testing targets. This is useful if your test libraries (e.g. GoogleTest) used by pw_unit_test have the testonly flag set. False by default for backwards compatibility.

CMake reference#

`pw_add_test`#

pw_add_test declares a single unit test suite.

Tip

Upstream Pigweed tests can be disabled in downstream projects by setting pw_unit_test_ENABLE_PW_ADD_TEST to OFF before adding the pigweed directory to an existing cmake build.

set(pw_unit_test_ENABLE_PW_ADD_TEST OFF)
add_subdirectory(path/to/pigweed pigweed)
set(pw_unit_test_ENABLE_PW_ADD_TEST ON)

Targets#

{NAME}: Depends on ${NAME}.run if pw_unit_test_AUTOMATIC_RUNNER is set, else it depends on ${NAME}.bin.

{NAME}.lib: Contains the provided test sources as a library target, which can then be linked into a test executable.

{NAME}.bin: A standalone executable which contains only the test sources specified in the pw_unit_test template.

{NAME}.run: Runs the unit test executable after building it if pw_unit_test_AUTOMATIC_RUNNER is set, else it fails to build.

Required arguments#

NAME#: Name to use for the produced test targets specified above.

Optional arguments#

SOURCES#: Source files for this library.

HEADERS#: Header files for this library.

PRIVATE_DEPS#: Private pw_target_link_targets arguments.

PRIVATE_INCLUDES#: Public target_include_directories argument.

PRIVATE_DEFINES#: Private target_compile_definitions arguments.

PRIVATE_COMPILE_OPTIONS#: Private target_compile_options arguments.

PRIVATE_LINK_OPTIONS#: Private target_link_options arguments.

Example#

include($ENV{PW_ROOT}/pw_unit_test/test.cmake)

pw_add_test(my_module.foo_test
  SOURCES
    foo_test.cc
  PRIVATE_DEPS
    my_module.foo
)

`pw_add_test_group`#

pw_add_test_group defines a collection of tests or other test groups.

Targets#

{NAME}: Depends on ${NAME}.run if pw_unit_test_AUTOMATIC_RUNNER is set, else it depends on ${NAME}.bin.

{NAME}.bundle: Depends on ${NAME}.bundle.run if pw_unit_test_AUTOMATIC_RUNNER is set, else it depends on ${NAME}.bundle.bin.

{NAME}.lib: Depends on ${NAME}.bundle.lib.

{NAME}.bin: Depends on the provided TESTS’s <test_dep>.bin targets.

{NAME}.run: Depends on the provided TESTS’s <test_dep>.run targets if pw_unit_test_AUTOMATIC_RUNNER is set, else it fails to build.

{NAME}.bundle.lib: Contains the provided tests bundled as a library target, which can then be linked into a test executable.

{NAME}.bundle.bin: Standalone executable which contains the bundled tests.

{NAME}.bundle.run: Runs the {NAME}.bundle.bin test bundle executable after building it if pw_unit_test_AUTOMATIC_RUNNER is set, else it fails to build.

Required arguments#

NAME#: The name of the executable target to be created.

TESTS#: pw_add_test targets and pw_add_test_group bundles to be included in this test bundle.

Example#

include($ENV{PW_ROOT}/pw_unit_test/test.cmake)

pw_add_test_group(tests
  TESTS
    bar_test
    foo_test
)

pw_add_test(foo_test
  # ...
)

pw_add_test(bar_test
  # ...
)

CMake build arguments#

pw_unit_test_BACKEND <target>#

The GoogleTest implementation to use for Pigweed unit tests. This library provides gtest/gtest.h and related headers. Defaults to pw_unit_test.light, which implements a subset of GoogleTest.

Type: string (CMake target name)

Usage: toolchain-controlled only

pw_unit_test_AUTOMATIC_RUNNER <executable>#

Path to a test runner to automatically run unit tests after they’re built.

If set, a pw_test target’s ${NAME} and ${NAME}.run targets will invoke the test runner specified by this argument, passing the path to the unit test to run. If this is unset, the pw_test target’s ${NAME} will only build the unit test(s) and ${NAME}.run will fail to build.

Type: string (name of an executable on the PATH, or path to an executable)

Usage: toolchain-controlled only

pw_unit_test_AUTOMATIC_RUNNER_ARGS <args>#

An optional list of strings to pass as args to the test runner specified by pw_unit_test_AUTOMATIC_RUNNER.

Type: list of strings (args to pass to pw_unit_test_AUTOMATIC_RUNNER)

Usage: toolchain-controlled only

pw_unit_test_AUTOMATIC_RUNNER_TIMEOUT_SECONDS <timeout_seconds>#

An optional timeout to apply when running the automatic runner. Timeout is in seconds. Defaults to empty which means no timeout.

Type: string (number of seconds to wait before killing test runner)

Usage: toolchain-controlled only

pw_unit_test_ADD_EXECUTABLE_FUNCTION <function name>#

The name of the CMake function used to build pw_unit_test executables. The provided function must take a NAME and a TEST_LIB argument which are the expected name of the executable target and the target which provides the unit test(s).

Type: string (name of a CMake function)

Usage: toolchain-controlled only

pw_unit_test_ADD_EXECUTABLE_FUNCTION_FILE <cmake file path>#

The path to the .cmake file that defines pw_unit_test_ADD_EXECUTABLE_FUNCTION.

Type: string (path to a .cmake file)

Usage: toolchain-controlled only

Zephyr backend tests#

Zephyr backend tests use Zephyr’s test runner twister. The test runner is installed into the Pigweed CLI and can be run by calling pw twister-runner. The runner intercepts a few arguments in order to add features to the normal test runner; beyond that, the runner just calls twister directly.

The runner will intercept the -T or --testsuite-root arguments and do the following:

For every testcase.yaml file under the testsuite root directory it appends -T path/to/testcase.yaml.
For every testtemplate.yaml it creates a new directory using the {name} field in the YAML file and the --build-dir to create a new test root at {build_dir}/{name}. It will then take the testcase node in the template and create a new {build_dir}/{name}/testcase.yaml. This new YAML file will be appended to the final twister command using -T {build_dir}/{name}.

Test templates#

Twister normally uses a combination of testcase.yaml files along CMakeLists.txt files which serve as the test’s entry point. This doesn’t work when trying to write tests side by side with the source. The twister runner introduces the concept of testtemplate.yaml which allows the test to live in the same directory as the source but is compatible with twister. The test template YAML file contains the following required keys:

name - The name of the test directory to create. This must be unique per twister run.
testcase - The content of this entry will be copied into a new {build_dir}/{name}/testcase.yaml file.

Additional fields are available in the template and are optional:

file-map - This key/value dictionary contains a mapping of relative file paths (reltive to the testtemplate.yaml file) to output relative file paths (relative to the generated {build_dir}/{name)). Each entry will create a symlink.
use-default-cmake - By default true and allows the test to leverage a common CMakeLists.txt that should fit the majority of test cases. It sets up a simple Zephyr app which uses the simple_printing_main.cc to run the tests. This CMake file also expects that the test will be a library created by pw_add_test. For example, if we wanted to test the pw_base64.base64_test unit test we would just need to pass TEST_LIB=pw_base64.base64_test as a CMake argument.
use-default-prj-conf - By default true and allows the test to leverage a common prj.conf that should fit the majority of test cases. It sets up C++20 and a few other common Kconfigs. Additional configs can be added as a part of the testtemplate.yaml using the extra_configs key.

Running the tests#

Automatically, tests will be picked up by pw presubmit --step zephyr_build. This presubmit test will call the twister-runner script to run all the tests defined in either testcase.yaml or testtemplate.yaml. Coverage reports can be found later in twister-out/coverage/.

pw_unit_test#

Quickstart#

Set up your build system#

Write tests#

Run tests#

Guides#

Choose a backend#

pw_unit_test:light API compatibility#

Create a custom main function#

Create event handlers#

Predefined event handlers#

Run a subset of test suites#

Skip tests in Bazel#

Run tests in static libraries#

Use upstream GoogleTest#

Run tests over serial#

Run tests over RPC#

Golden file testing with pw_golden_test#

C++ API reference#

Python API reference#

pw_unit_test.serial_test_runner#

pw_unit_test.rpc#

Build helper libraries#

Bazel API reference#

pw_cc_test#

Label flags#

GN reference#

pw_test#

Targets#

Arguments#

Example#

pw_test_group#

Targets#

Arguments#

Example#

pw_facade_test#

GN build arguments#

CMake reference#

pw_add_test#

Targets#

Required arguments#

Optional arguments#

Example#

pw_add_test_group#

Targets#

Required arguments#

Example#

CMake build arguments#

Zephyr backend tests#

Test templates#

Running the tests#

`pw_unit_test:light` API compatibility#

Create a custom `main` function#

Golden file testing with `pw_golden_test`#

`pw_unit_test.serial_test_runner`#

`pw_unit_test.rpc`#

`pw_cc_test`#

`pw_test`#

`pw_test_group`#

`pw_facade_test`#

`pw_add_test`#

`pw_add_test_group`#