Run a test component

This guide shows you how to build Fuchsia to include a test package from Fuchsia's source //examples directory and run tests on your Fuchsia target.

Prerequisites

Before you can run this test component, you must:

Exploring the example

The Hello, world! examples includes unit test components written in the various supported languages. A test component has two key elements:

  • An executable test suite written in a supported language.
  • A BUILD.gn file to define the test component build target and include it in a Fuchsia test package.

Executable test suite

Fuchsia test suites are built as components and execute within a test runner for supported testing frameworks, such as GoogleTest. The test suite binary includes test cases written against these language-specific frameworks.

C++

#include <gtest/gtest.h>

TEST(HelloWorldTest, True) { EXPECT_TRUE(true); }

Rust

#[cfg(test)]
mod tests {
    #[fuchsia::test]
    fn it_works() {
        assert_eq!(true, true);
    }
}

For more details on testing Fuchsia components, see Testing with Components

BUILD.gn

The BUILD.gn file declares build targets for fuchsia_unittest_package(). This template is specifically designed to package components containing tests.

C++

executable("unittests") {
  testonly = true
  output_name = "hello_world_cpp_test_bin"
  sources = [ "hello_world_unittest.cc" ]
  deps = [ "//src/lib/fxl/test:gtest_main" ]
}

fuchsia_unittest_package("hello-world-cpp-unittests") {
  deps = [ ":unittests" ]
}

Rust

rustc_binary("bin") {
  name = "hello_world_rust"

  # Generates the "bin_test" build target
  with_unit_tests = true
  edition = "2021"

  deps = []
  test_deps = [ "//src/lib/fuchsia" ]

  sources = [ "src/main.rs" ]
}

fuchsia_unittest_package("hello-world-rust-tests") {
  deps = [ ":bin_test" ]
}

To learn more about how Fuchsia uses GN to define test packages, see: Building components.

Include the example tests in your Fuchsia image

To include the example package in your build configuration, use the --with flag when setting your product and board environment:

fx set product.board --with //examples/hello_world:tests

For a Fuchsia emulator with the minimum build configuration, the command is:

fx set core.x64 --with //examples/hello_world:tests

In this example, core is a product with a minimal feature set, which includes common network capabilities, and x64 refers to the x64 architecture.

For a Fuchsia device with the minimum build configuration, the command is:

fx set core.x64 --with //examples/hello_world:tests

See Configure a build for more options.

Once you have set your build configuration, build Fuchsia with the following command:

fx build

You now have a build that includes the example tests that can be fetched and launched on demand.

Run the test suite

  1. Open a terminal and run fx serve:

    fx serve

  2. Open another terminal and run the hello-world unit tests:

    C++

    fx test hello-world-cpp-unittests

    Rust

    fx test hello-world-rust-tests

This command prints the following output:

C++

$ fx test hello-world-cpp-unittests
...

PASS: 0 FAIL: 0 00:00 🤔  fx shell run-test-suite '--max-severity-logs WARN' fuchsia-pkg://fuchsia.com/hello-world-cpp-unittests?hash=c34ed8b2ea21fd5158f1de77a5581a4b5123161ef851eea430768a00efc1cbbf#meta/hello-world-cpp-unittests.cm
>> Runtime has exceeded 2 seconds (adjust this value with the -s|--slow flag)

Running test 'fuchsia-pkg://fuchsia.com/hello-world-cpp-unittests?hash=c34ed8b2ea21fd5158f1de77a5581a4b5123161ef851eea430768a00efc1cbbf#meta/hello-world-cpp-unittests.cm'
[RUNNING] HelloWorldTest.True
[PASSED]  HelloWorldTest.True

1 out of 1 tests passed...
fuchsia-pkg://fuchsia.com/hello-world-cpp-unittests?hash=c34ed8b2ea21fd5158f1de77a5581a4b5123161ef851eea430768a00efc1cbbf#meta/hello-world-cpp-unittests.cm completed with result: PASSED

PASS: 1 FAIL: 0 00:15 ✅  fx shell run-test-suite '--max-severity-logs WARN' fuchsia-pkg://fuchsia.com/hello-world-cpp-unittests?hash=c34ed8b2ea21fd5158f1de77a5581a4b5123161ef851eea430768a00efc1cbbf#meta/hello-world-cpp-unittests.cm

🎉  Ran 1 tests with 0 failures (use the -v flag to see each test) 🎉

Rust

$ fx test hello-world-rust-tests
...

PASS: 0 FAIL: 0 00:00 🤔  fx shell run-test-suite '--max-severity-logs WARN' fuchsia-pkg://fuchsia.com/hello-world-rust-tests?hash=45cc85adaa09af18c575c45be942d72e173719c53e69d879eeb9602fa38e4884#meta/hello-world-rust-tests.cm
>> Runtime has exceeded 2 seconds (adjust this value with the -s|--slow flag)

Running test 'fuchsia-pkg://fuchsia.com/hello-world-rust-tests?hash=45cc85adaa09af18c575c45be942d72e173719c53e69d879eeb9602fa38e4884#meta/hello-world-rust-tests.cm'
[RUNNING] hello_tests::greeting_test
[RUNNING] hello_tests::my_test
[RUNNING] tests::it_works
[PASSED]  tests::it_works
[PASSED]  hello_tests::my_test
[PASSED]  hello_tests::greeting_test

3 out of 3 tests passed...
fuchsia-pkg://fuchsia.com/hello-world-rust-tests?hash=45cc85adaa09af18c575c45be942d72e173719c53e69d879eeb9602fa38e4884#meta/hello-world-rust-tests.cm completed with result: PASSED

PASS: 1 FAIL: 0 00:15 ✅  fx shell run-test-suite '--max-severity-logs WARN' fuchsia-pkg://fuchsia.com/hello-world-rust-tests?hash=45cc85adaa09af18c575c45be942d72e173719c53e69d879eeb9602fa38e4884#meta/hello-world-rust-tests.cm