This documentation concerns xr_browser_test.h, xr_browser_test.cc, and files that use them or their subclasses.
These files port the framework used by XR instrumentation tests (located in //chrome/android/javatests/src/org/chromium/chrome/browser/vr/ and documented in //chrome/android/javatests/src/org/chromium/chrome/browser/vr/*.md) for use in browser tests in order to test XR features on desktop platforms.
This is pretty much a direct port, with the same JavaScript/HTML files being used for both and the Java/C++ code being functionally equivalent to each other, so the instrumentation test's documentation on writing tests using the framework is applicable here, too. As such, this documentation only covers any notable differences between the two implementations.
Both the instrumentation tests and browser tests have hardware/software restrictions - in the case of browser tests, XR is only supported on Windows 8 and later (or Windows 7 with a non-standard patch applied) with a GPU that supports DirectX 11.1.
Instrumentation tests handle restrictions with the @Restriction annotation, but browser tests don‘t have any equivalent functionality. However, since the browser tests don’t require any setup outside of the tests like instrumentation tests do (which require the paired viewer, etc. to be changed), having the tests in their own target is sufficient to prevent us from running into hardware incompatibility issues.
Instrumentation tests are able to add and remove command line switches on a per-test-case basis using @CommandLine annotations, but equivalent functionality does not exist in browser tests.
Instead, if different command line flags are needed, a new class will need to be created that extends the correct type of *BrowserTestBase and overrides the flags that are set in its SetUp function.
The tests are compiled in the xr_browser_tests target, which is currently only defined on Windows.
Once compiled, the tests can be run using the following command line:
xr_browser_tests.exe --enable-gpu --test-launcher-jobs=1 --enable-pixel-output-in-tests