Negative assertions¶

Horizon-QA is aimed at tests that assert a bad state never occurs over a tick window. That category covers most of the regressions a traditional unit test will quietly miss.

Core pattern¶

@GameTest(template = "ebf_no_coils", timeoutTicks = 60)
public static void doesNotFormWithoutCoils(GameTestHelper helper) {
    Multiblock ebf = helper.gtnh().multiblock(at(1, 0, 0));
    ebf.assertNeverForms("EBF formed without coils");
}

For GT multiblock formation tests, assertNeverForms(...) forces a structure check immediately, registers a per-tick negative invariant, and succeeds at timeout. That forced first check matters when you mutate an exported valid template: the controller may otherwise still hold a stale mMachine=true value from placement.

The equivalent generic pattern is:

helper.onEachTick(() -> helper.assertFalse(ebf.isFormed(), "EBF formed without coils"));
helper.succeedAtTimeout();

Call	Role
`onEachTick(Runnable)`	Runs the callback every test tick until the test passes or fails
`assertFalse(ebf.isFormed(), …)`	Fails immediately on the tick where the machine forms
`succeedAtTimeout()`	Passes at the END of the final allowed tick if nothing failed

The final allowed tick is still observed before succeedAtTimeout() passes.

A transient formation fails on that tick, not at the end of the window. The framework does not need to wait out the full timeout to report the failure.

When to use `succeedWhen` instead¶

Use succeedWhen(() -> condition) when you wait for a positive eventual state:

helper.succeedWhen(() -> helper.getBlockState(pos).getBlock() == Blocks.redstone_block);

succeedWhen is not the right tool for invariants

succeedWhen exits the moment its predicate becomes true. An invariant that should hold every tick wants onEachTick + succeedAtTimeout, not succeedWhen.

Continuous invariants¶

Combine multiple checks in a single callback so they share the same window:

helper.onEachTick(() -> {
    helper.assertFalse(ebf.isFormed(), "formed");
    helper.assertFalse(ebf.isProcessing(), "started recipe");
});
helper.succeedAtTimeout();

Sequences vs. polling¶

For staged scenarios such as "insert items, then assert no recipe for 40 ticks, then supply EU", prefer Sequences & timing over manual tick counters inside onEachTick. Sequences handle the scheduling; tick counters never quite do.

Design alignment¶

Negative tests implement Design principle 5, "Negative tests are load-bearing". Also see Principle 4, "Wait on state, not ticks": tick counts on @GameTest are timeouts, never recipe-duration proxies.