> To reproduce a CI failure, see the section on [Running with Sanitizers](#running-with-sanitizers).
The easiest way to run tests is to use the `ladybird.sh` script. The LibWeb tests are registered with CMake as a test in
`Ladybird/CMakeLists.txt`. Using the built-in test filtering, you can run all tests with `Meta/ladybird.sh test` or run
just the LibWeb tests with `Meta/ladybird.sh test LibWeb`. The second way is to invoke the headless browser test runner
directly. See the invocation in `Ladybird/CMakeLists.txt` for the expected command line arguments.
A third way is to invoke `ctest` directly. The simplest method is to use the `default` preset from ``CMakePresets.json``:
```sh
cmake --preset default
cmake --build --preset default
ctest --preset default
```
If you want to avoid building and running LibWeb tests, you can use a Lagom-only build.
```sh
cmake -GNinja -S Meta/Lagom -B Build/lagom
```
The tests can be run via ninja after doing a build. Note that `test-js` requires the `LADYBIRD_SOURCE_DIR` environment variable to be set
to the root of the ladybird source tree.
```sh
# /path/to/ladybird repository
export LADYBIRD_SOURCE_DIR=${PWD}
cd Build/lagom
ninja
ninja test
```
To see the stdout/stderr output of failing tests, the recommended way is to set the environment variable [`CTEST_OUTPUT_ON_FAILURE`](https://cmake.org/cmake/help/latest/manual/ctest.1.html#options) to 1.
```sh
CTEST_OUTPUT_ON_FAILURE=1 ninja test
# or, using ctest directly...
ctest --output-on-failure
```
### Running with Sanitizers
CI runs host tests with Address Sanitizer and Undefined Sanitizer instrumentation enabled. These tools catch many
classes of common C++ errors, including memory leaks, out of bounds access to stack and heap allocations, and
signed integer overflow. For more info on the sanitizers, check out the Address Sanitizer [wiki page](https://github.com/google/sanitizers/wiki),
or the Undefined Sanitizer [documentation](https://clang.llvm.org/docs/UndefinedBehaviorSanitizer.html) from clang.
Note that a sanitizer build will take significantly longer than a non-sanitizer build, and will mess with caches in tools such as `ccache`.
The sanitizers can be enabled with the `-DENABLE_FOO_SANITIZER` set of flags.
The simplest way to enable sanitizers is to use the `Sanitizer` preset.
```sh
cmake --preset Sanitizer
cmake --build --preset Sanitizer
ctest --preset Sanitizer
```
Or from a Lagom build:
To ensure that the test behaves the same way as CI, make sure to set the ASAN_OPTIONS and UBSAN_OPTIONS appropriately.
The Sanitizer test preset already sets these environment variables.
You can import certain Web Platform Tests (WPT) tests into your Ladybird clone(if they’re tests of type that can be imported— and especially if any code changes you’re making cause Ladybird to pass any WPT tests it hasn’t yet been passing). Here’s how:
That is, you give `./Meta/WPT.sh import` the path part of any `http://wpt.live/` URL for a WPT test you want to import. It will then download both that test and any of its JavaScript scripts, copy those to the `Tests/LibWeb/<test-type>/input/wpt-import` directory, run the test, and then in the `Tests/LibWeb/<test-type>/expected/wpt-import` directory, it will create a file with the expected results from the test.
