deepseek-harness/docs/testing.md

Testing policy

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How this repo tests, tier by tier, and the rules that keep a green suite meaningful. Commands live in root 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).
• Snapshot (pnpm run test:snapshot): boots the real example subprocess, replays a recorded session keyless, diffs normalized stdout + the re-persisted log against committed goldens (snapshot RFC). Use pnpm run test:snapshot:record when the model transcript should change; use pnpm run test:snapshot:refresh when the committed transcript is still the right mock LLM input and replay goldens need keyless rewrite. Review the golden diff. System-prompt/tool-schema content is pinned by ONE scenario (text-turn) and tokenized in every other fixture, so a prompt or schema edit churns one committed line (pinned-header RFC).

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). 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).

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).

When a snapshot test is required

Any change affecting the editor-facing transcript or end-to-end agent UX — the ACP bridge, the loop's observable output, tool presentation — adds or updates a scenario in the owning example's snapshot suite (examples/<name>/tests/snapshots/, a scenario table over the dsh-acp-snapshot suite factory; examples/acp-agent is the primary suite), or states in the PR why none applies. New capability seams, lifecycle shapes, or transcript surfaces name their coverage at every tier at plan time and verify the harness can express it — a harness gap is scheduled work, not a mid-build surprise.