# Testing policy How this repo tests, tier by tier, and the rules that keep a green suite meaningful. Commands live in root [AGENTS.md](../AGENTS.md); linked RFCs carry the rationale. ## Tiers - **Unit** (`pnpm run test`): vitest over `packages|examples/*/tests/**/*.spec.ts`, colocated with what they test. Every registry gets an HMR-safety test (dispose the contributing fiber, assert cleanup). Prefer edge cases, error paths, event ordering, concurrency races, and permanent contract regressions (see `packages/core/agent-loop/tests/contract-regressions.spec.ts`). - **Coverage gate** (`pnpm run test:coverage`): the gating run, per-file 100% on `packages/*/*/src`. An uncovered line is often dead code the gate is correctly flagging for deletion, not a missing test to bolt on. Line coverage is necessary, never sufficient — it proves lines ran, not that the feature works as shipped. - **Real-API e2e** (`pnpm run test:e2e`): with-key tests against live provider APIs — the DeepSeek model plus provider-specific smokes that gate on their own keys (`EXA_API_KEY`, `PERPLEXITY_API_KEY`, …); each suite self-skips without its key so keyless CI stays green ([real-API e2e RFC](rfc/implemented/testing/2026-06-19-real-api-e2e-ci.md)). - **Snapshot** (`pnpm run test:snapshot`): real example subprocesses replay recorded model sessions keylessly and compare normalized stdout plus re-persisted logs ([snapshot RFC](rfc/implemented/testing/2026-06-19-acp-snapshot-tests.md)). The primary suite pins ACP JSON-RPC; the headless projection reuses `advanced-toolchain` for `stream-json`. Use `pnpm run test:snapshot:record` when the model transcript changes and `pnpm run test:snapshot:refresh` when only replay outputs change; review the golden diff. One scenario per header class pins system-prompt/tool-schema content; other fixtures tokenize it ([pinned-header RFC](rfc/implemented/testing/2026-07-06-pin-request-header-content-in-one-scenario.md)). ## The with-key policy: inference is cheap here We are DeepSeek — do not ration real-API tests. A no-key test proves plumbing; only a with-key run proves the agent works against a real model. Write many: file-writing prompts, multi-turn conversations, tool use, cancellation mid-stream. Highest-value are **smoke tests** that boot the real example, send one real prompt, and check the world — they catch the "green unit tests, broken product" class that mocks structurally cannot ([postmortem 0001](postmortem/0001-acp-default-export-drops-inject.md)). The self-skip exists only so secretless CI and keyless contributors aren't blocked; it is not a cost signal. Every example ships a keyless smoke and — unless keyless-by-nature — a with-key smoke ([examples/AGENTS.md](../examples/AGENTS.md)). ## Prefer the real implementation over a mock Mock only the genuinely expensive or non-deterministic boundary (the LLM adapter, the network, the clock); keep everything downstream real. A hand-rolled stand-in proves the bridge moves bytes, not that the shipping tool behaves as asserted — the two drift while the test stays green. Example: bridge tool-call tests run the scripted mock MODEL but the real tool + real executor (`makeBridgeHarness({ withBash: true })` plugs `dsh-bash-local` + `dsh-tool-bash` and runs an actual `echo`). ## Verify the world, not the self-report An e2e assertion re-runs the command or re-reads the file externally; a keyword probe on the agent's own output lets a cheating agent pass. Assert untouched files are byte-identical. e2e tests own their resources: create the harness in the test, dispose in `afterEach` (even on failure/retry/timeout); shared fixtures live in a plain `tests/harness.ts`, never another `*.e2e.ts` (importing a spec re-registers its `describe` and duplicates real API calls). ## Test the real entry path - Product-visible plugins require a non-unit REAL-composition test. Hand-built `ctx.plugin(...)` suites are insufficient: boot test-only `cordis.yml` through Loader and app/process, mock only external/nondeterministic boundaries, and assert model-visible request/log, durable state, or user-visible output. Keep opt-ins out of shipped defaults. - A guard only guards if the regression actually fails it. For a plugin without `inject` (bundle/composition plugins), a Loader smoke stays green under a broken export shape — add an explicit `expect('default' in mod).toBe(false)` plus an `unwrapExports` round-trip assertion, and prove it: introduce the regression, watch red, revert. - "Real entry path" means the published artifact: the package `bin` points at built `lib/bin.js` under plain `node`, which tsx masks (settle races, module resolution, a swallowed load failure exiting 0). The same applies to any non-index runtime entry the built package resolves at run time (the worker-thread runtime's sibling `lib/worker.cjs`). Keep the built-artifact smokes green (`packages/ui/*/tests/built-bin.e2e.ts`, `packages/code-runtime/code-runtime-worker/tests/built-lib.e2e.ts`), and assert a genuinely-missing config exits non-zero. - An e2e that spawns an example from a temp cwd sets `TSX_TSCONFIG_PATH` to the repo-root tsconfig, or it silently falls back to stale built `lib/` ([examples/AGENTS.md](../examples/AGENTS.md)). ## When a snapshot test is required A change affecting an editor transcript, headless event stream, or agent UX adds or updates the owning `examples//tests/snapshots/` scenario, or explains its omission in the PR. `examples/acp-agent` hosts the primary [`dsh-acp-snapshot`](../packages/support/acp-snapshot/README.md) table and the headless `stream-json` projection. Plans for new capability seams, lifecycle shapes, or transcript surfaces identify every test tier and any required harness work before implementation.