Tests must properly clean up resources and handle conditional execution regardless of test outcome. This includes removing temporary files, resetting global state, and gracefully handling feature flag conditions. For file-based tests, use RAII patterns or explicit cleanup in finally blocks to ensure resources are released even when tests fail: ```cpp KJ_TEST("PerfettoSession basic functionality") { auto traceFile = getTempFileName("perfetto-test"); // Use RAII or try-finally pattern KJ_DEFER(removeFile(traceFile.cStr())); { PerfettoSession session(traceFile, "workerd"); // ... test operations } KJ_ASSERT(fileExists(traceFile.cStr())); // File automatically cleaned up by KJ_DEFER } ``` For tests that depend on feature flags or autogates, check conditions early and skip gracefully rather than creating complex conditional logic: ```cpp KJ_TEST("feature dependent test") { if (util::Autogate::isEnabled("feature-flag")) { KJ_LOG(INFO, "Skipping test due to autogate being enabled"); return; } // ... rest of test } ``` This prevents resource leaks, reduces flaky tests, and makes test behavior predictable across different environments and configurations.