A large collection of as-small-as-possible tests for your Game Boy emulator that check for a wide variety of cycle-accurate timing issues and quirks found on the real Game Boy hardware. All tests in this repo have been checked on real hardware (version DMG-CPU-08 I believe).

These tests were originally used to debug GateBoy, and are not intended to verify basic functionality of your emulator. They are solely for tracking down cycle-accuracy issues in emulators that are already functional. GateBoy, for example, passes all but a handful of these tests because it does not currently simulate asynchronous timing glitches correctly.

I originally wrote these tests because the other available test ROMs do a bunch of setup/teardown that made it painfully slow to iterate on back when GateBoy could only run at a tiny fraction of realtime. These tests instead check exactly one register or memory address at one specific cycle after boot and then write a pass/fail value to VRAM so the result is visible onscreen.

Prebuilt ROMs are in bin/ and do not require your emulator to have a mapper implemented.

Most tests will complete in a few hundred cycles, except for those that need to check behavior after VBLANK.

The test will write results to ram at 0xFF80-0xFF82 and then display either stripes on the LCD if the test passes, or black if the test fails.

• 0xFF80 - Test result
• 0xFF81 - Expected result
• 0xFF82 - 0x01 if the test passed, 0xFF if the test failed.

Install wla-dx, then run "build.sh" in the repo root.