Adopt a consistent testing standard that prevents flaky behavior, leaked goroutines, and false positives. **1) Always register cleanup for started resources** - Prefer `t.Cleanup(...)` / `tb.Cleanup(...)` over scattered `defer`s. - Use it for: clients, servers, accumulators/tickers, streaming helpers, and `Init(...)` results. ```go bf, err := Init(ctx, cfg) require.NoError(t, err) t.Cleanup(func() { bf.Shutdown() }) ``` **2) Make concurrency/time-sensitive tests deterministic** - Avoid fixed sleeps like `time.Sleep(3 * time.Millisecond)` for synchronization. - Use a bounded poll/wait with a deadline. ```go deadline := time.Now().Add(2 * time.Second) for time.Now().Before(deadline) { if body.closeCount.Load() > 0 { break } time.Sleep(2 * time.Millisecond) } stop(); cleanup() ``` **3) Ensure assertions are non-vacuous and validate invariants** - Don’t rely on branches that may skip the assertion. - Assert the exact behavior that should occur (e.g., “role dropped” or “snapshot deep-copied”). ```go attachBilledUsageFromContext(ctx, bifrostErr) // Mutate original after attach; snapshot must not change. usage.PromptTokens = 999 require.Equal(t, 10, bifrostErr.ExtraFields.BilledUsage.PromptTokens) ``` **4) Keep mocks faithful to production side effects/commit semantics** - If production “updates only on success,” mocks must not mutate global/shared state until validation passes. - Avoid pointer-aliasing bugs where rollback logic doesn’t fully revert state. ```go candidate := budgets[i] // copy candidate.IsCalendarAligned = calendarAligned if err := candidate.SetOverrideAt(...); err != nil { return nil, err } budgets[i] = candidate // commit only on success ``` **5) Fail fast during test setup** - When setup steps can fail (e.g., sending initial chunks), check return values immediately and `t.Fatalf(...)` with a setup-specific message. - This prevents cascaded failures that obscure the root cause. ```go if ok := a.GateSend(traceID, chunk0, false, false, ch, ctx); !ok { t.Fatalf("setup chunk 0: GateSend returned false") } ```