A record/replay testing framework for games written in C.

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GameTest captures keyboard, mouse, and gamepad input during a recording session and injects that input back deterministically during replay, allowing automated regression testing of game logic without mocking or restructuring the game loop.

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Documentation

Document	Description
EXAMPLE.md	Walkthrough of the bundled Snake game — initialization, seed pinning, sync signals, inline assertions, and score verification.
HOW_IT_WORKS.md	Record/replay lifecycle, input capture, Pin, Track, and SyncSignal.
TOOL.md	GameTest-Tool CLI reference.
DETAILS.md	Hard limits, known edge cases, and the complete API reference.

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Building

CMake 3.19 or later is required.

cmake -B build
cmake --build build

CMake options

Option	Default	Description
GMT_BUILD_SHARED	OFF	Build GameTest as a shared library instead of static.
GMT_BUILD_EXAMPLE	ON	Build the bundled example game (requires internet access; fetches GLFW 3.4).
GMT_BUILD_TOOL	ON	Build GameTest-Tool, the CLI runner.

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Integration

Link the GameTest target and include GameTest.h.

#include <GameTest.h>

Call GMT_Init once at startup, GMT_Update at the top of every frame, and GMT_Quit on shutdown:

GMT_Setup setup = {0};
setup.mode      = mode;       // GMT_Mode_RECORD, GMT_Mode_REPLAY, or GMT_Mode_DISABLED
setup.test_path = test_path;  // path to the .gmt file
GMT_Init(&setup);

while (running) {
    GMT_Update();    // must be first, before any input polling
    PollInput();
    UpdateGame(dt);
    Render();
}

GMT_PrintReport();
GMT_Quit();

Parse the mode and path from command-line arguments rather than hard-coding them:

char path[512];
GMT_Mode mode;
GMT_ParseTestFilePath((const char**)argv, argc, path, sizeof(path));
GMT_ParseTestMode((const char**)argv, argc, &mode);

The framework accepts --test=<path> and --test-mode=record|replay|disabled. These are the arguments that GameTest-Tool passes automatically when it launches your game.

Disabling at compile time

Define GMT_DISABLE before including the header to turn every macro into a no-op. No object code is generated and no runtime overhead is incurred.

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License

MIT. Copyright (c) 2026 Christian Luppi.