Fairy Fox

Updates · · pokered-save-editor-2update

Pokered Save Editor 2: a test suite, and the save-corruption bug it caught

An automated QtTest/CTest suite goes in — and immediately turns up an off-by-one that was clobbering a byte on every save.

A comprehensive automated test suite now covers Pokered Save Editor 2, built on QtTest and CTest. It exercises the save-file engine, the game database, and the randomiser. To make the UI’s logic testable in the first place, that logic was extracted into a standalone appcore library, so the models can now be unit-tested rather than only clicked through by hand.

The bug it caught on day one

The headline find was a save-corruption bug. The checksum for the second bank of PC boxes was being written one byte early — which also overwrote the last data byte of Box 6 on every save of a progressed file:

// savefiletoolset.cpp — recalcChecksums()
- data[0x5A4B] = getChecksum(0x4000, 0x1A4B);  // wrong: clobbers Box 6's last byte
+ data[0x5A4C] = getChecksum(0x4000, 0x1A4C);  // correct address + range

The corrected address matches the original game’s own sBank2AllBoxesChecksum location in the pret/pokered disassembly, which is the project’s oracle for anything save-format related. With the fix in, a real save round-trips byte-for-byte:

$ ctest --output-on-failure -R roundtrip
1/1 Test #1: tst_roundtrip ....................   Passed
100% tests passed, 0 tests failed out of 1

This is exactly the class of bug that’s almost impossible to spot by eye and trivial for a round-trip test to catch — and it’s the kind this editor cares about most, since its core promise is to change only the bytes an edit requires.

A crash, and the randomiser

A second find was a crash in the Day Care teardown when the Day Care was empty, from an unconditional cleanup of a pointer that could be null:

- pokemon->deleteLater();
+ if (pokemon != nullptr) pokemon->deleteLater();

The randomiser also reached the point of running end to end with coverage for its current scope — invariants checked across repeated runs, plus byte fidelity on the results. Features that aren’t built yet, like map and Hall of Fame randomisation, are explicitly held back with re-enable notes rather than left half-wired.

References

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