Third Party API Integration Test

Write Go integration tests for real third-party API calls using explicit run gates, predictable safeguards, and strong contract assertions.

Scope

• Validate external API integration end-to-end with real config and real client.
• Keep tests opt-in by default so normal CI/unit workflows are not blocked.
• Follow the host repository's existing style — its assertion library (testify/require, testify/assert, or stdlib t.Fatalf), its config loader, and its test-package convention. The examples below use testify/require and config.MustLoad() as one common shape; mirror what the repo already does rather than importing a new dependency. Clear skip conditions and a bounded timeout are required regardless.
• Apply to any third-party API integration.
• Treat vendor examples (MCS/USS/etc.) as templates, not scope limits.
• The NON-NEGOTIABLE parts are the safety gates (run gate, prod/host/account fail-closed checks, destructive gating, bounded budget, ID/URL redaction) — not the choice of assertion or config library.

Scope Validation Gate

Confirm the task targets a third-party vendor API:

• Third-party HTTP or gRPC API client → proceed
• Internal service/handler (own HTTP server) → redirect to $api-integration-test, STOP
• Pure unit test → redirect to $unit-test, STOP
• Full end-to-end browser journey → out of scope, inform user, STOP

Hard stop: If the target is not a third-party vendor API, the entire remaining workflow is skipped. Output only: (1) scope verdict, (2) recommended skill or approach, (3) reason. Do NOT generate test code, do NOT proceed to subsequent gates.

Required Pattern

1. Keep file name as <client>_integration_test.go, in the package the repo uses for tests (same package, or its _test external package — match the surrounding convention). Name each integration test function with an Integration marker (e.g. TestStripe_CreateCharge_Integration): the runner refuses to report success unless at least one …Integration test actually PASSED, which keeps a plain unit test from masquerading as a passed integration run (override the marker via VENDOR_TEST_NAME_MATCH).
2. Add both build constraints at file top (for backward compatibility):
   • //go:build integration (Go 1.17+)
   • // +build integration (Go <1.17 compat)
3. Add explicit run gate env var (example: THIRDPARTY_INTEGRATION=1 or vendor-specific gate), otherwise t.Skip(...).
4. Validate required runtime env vars up front (ENV, CONFIG_DIR, the API base URL, the vendor test account, target IDs). When the run gate is set but a required var is missing/empty, t.Fatalf — do NOT t.Skip (see §Skip vs Fail (CI Integrity)).
5. Block production/live vendor targets by ENV and by resolved host and account (never ENV alone):
   • refuse if ENV is prod/production, OR the base-URL host is not on the explicit sandbox allowlist (VENDOR_SANDBOX_HOSTS), OR the vendor account is not a designated test account (VENDOR_TEST_ACCOUNTS) — unless INTEGRATION_ALLOW_PROD=1. When the gate is set, this refusal is t.Fatalf, not t.Skip. Use requireVendorIntegration (§Go Implementation Baseline).
6. Parse and validate env var payloads:
   • Always strings.TrimSpace before comparison or use
   • Use strconv.ParseInt for numeric IDs
   • Split comma-separated lists and validate each element
   • Log only non-sensitive parsed values at t.Logf; mask identifiers with maskID and never log secrets/tokens (raw account/customer/tenant/target IDs are sensitive)
7. Load runtime config via the project's existing config loader (e.g. config.MustLoad() — use whatever the repo already uses; do not introduce a new config mechanism for the test).
8. Build real third-party client with production code path.
9. Use context.WithTimeout(...) to prevent hanging requests.
10. Use bounded retry policy only when justified:

• default: no retry
• if enabled: max 2 retries (3 total attempts), bounded backoff, no infinite loop. Rate-limit (429/Retry-After) retries count toward this same budget — getHonoringRateLimit is called with maxRetries=2.

11. Execute real API call and assert both:

• protocol-level contract (status/code/required response fields)
• business-level invariant (identifier consistency, semantic constraints)

12. For expected failure paths, assert explicit error type/code (not only require.Error).
13. Define test data lifecycle explicitly:

• setup source, idempotency key strategy, cleanup or safe reuse policy.

Skip vs Fail (CI Integrity)

t.Skip on a misconfigured run is a false green: go test exits 0 when every test skips, so a CI job that lost its config — or points at a live vendor — passes silently.

Once THIRDPARTY_INTEGRATION=1 is set, the only acceptable t.Skip is a destructive/scaffold opt-in tier that the base gate does not depend on. Everything else becomes t.Fatalf.

An individual test calling t.Skip is fine, but a whole run in which every test skipped verified nothing — run_vendor_integration.sh treats that (and a -run pattern matching nothing) as a failure, not a green PASS. So point an all-destructive CI job at its own package/-run scope and give it INTEGRATION_ALLOW_DESTRUCTIVE=1; a destructive job that skips everything is a misconfiguration the runner surfaces.

Go Implementation Baseline

The canonical prod/account/destructive safety helpers — requireVendorIntegration, assertTestAccount, isProdVendorTarget, assertVendorDestructiveSafe, maskID, redactURL, unwrapURLErr, parseRetryAfter, the callBudget/budgetTransport cost guards, getHonoringRateLimit, and the gRPC counterparts grpcTargetHost / isProdGRPCTarget / redactGRPCTarget / requireVendorGRPCIntegration / assertVendorGRPCDestructiveSafe — live in:

• references/go-baseline.md

Copy them into the test package as written. They fail CLOSED (a sandbox host must be on VENDOR_SANDBOX_HOSTS; a test account must be on VENDOR_TEST_ACCOUNTS) and are kept token-identical to the regression fixture, which is why they are a separate reference rather than inlined here — do not paraphrase the safety logic.

references/vendor-examples.md shows a full test that calls a real endpoint through the project's vendor client using these helpers plus a bounded call budget (newVendorBudget/ spend), real Retry-After handling (getHonoringRateLimit), and ID masking. gRPC vendors use isProdGRPCTarget for the sandbox check.

Configuration Gate (Mandatory)

Before generating or updating test code, apply the gate in:

• references/common-integration-gate.md

Vendor-Specific Safety Additions (executable rules)

These are concrete, testable rules — not principles. A behavioral fixture exercises each.

1. Sandbox host allowlist (fail closed). A vendor target is non-prod only if its host is on VENDOR_SANDBOX_HOSTS. Unset or non-matching host → treated as production (refuse).
2. Test account allowlist (fail closed). VENDOR_TEST_ACCOUNTS is required; the account/ project/tenant must be on it (assertTestAccount). A prod account like acct_live_9 is refused.
3. Production writes forbidden under ALL flags. INTEGRATION_ALLOW_PROD=1 permits READ-only prod tests, never writes. A destructive call against a prod/live target fails even with ALLOW_PROD=1 + ALLOW_DESTRUCTIVE=1 (assertVendorDestructiveSafe).
4. Mutations require an idempotency key. Destructive/write calls must pass a non-empty Idempotency-Key (also protects against duplicate charges on retry).
5. Bounded call budget (cost control). Cap real calls with VENDOR_MAX_CALLS (default 20); route every call through a budget that t.Fatalfs when exceeded — a runaway loop against a paid API must not silently rack up cost.
6. Retry-After / 429 handling. On 429, honor the Retry-After header (do not hammer), and classify the failure as rate-limit, never contract. Assert X-RateLimit-Remaining/Retry-After when the vendor sends them.
7. Mask sensitive IDs and secrets. Never log tokens, API keys, or raw customer/tenant/account IDs. Mask IDs in t.Logf/assertions (e.g. acct_1234 → acct_…34); redact Authorization.
8. gRPC specifics (when the vendor is gRPC): gate reads with requireVendorGRPCIntegration and writes with assertVendorGRPCDestructiveSafe (same rules as their HTTP counterparts). Assert status.Code(err) (not string matching), defer conn.Close(), and set a deadline via context.WithTimeout on every RPC. Map vendor codes to your domain errors at the boundary.
9. Retry policy bounded and explicit. Default no retry; if enabled, max 1-2 with bounded backoff, honoring ctx.Done() — no hidden infinite retries.

Safety Rules

• Use dedicated test tenant/account identifiers only (validated against VENDOR_TEST_ACCOUNTS).
• Prefer idempotent or low-risk API operations.
• Never hardcode secrets/tokens in test source; never log tokens or raw customer/tenant IDs (mask them).
• Skip vs Fail: t.Skip only when the run gate is off (or for a destructive/scaffold opt-in tier). When the gate is set but a required var is missing, or the target is prod/non-sandbox, t.Fatalf — a silent skip false-greens CI. See §Skip vs Fail (CI Integrity).
• Keep timeout strict (for example 10-30s) and avoid unbounded retries.
• Refuse production/live targets (by ENV, host, and account) unless explicit override is provided.

Execution

Use vendor-specific run commands documented in:

• references/vendor-examples.md

Tool-permission note. A strict Bash(go test*) allowlist matches only a command whose FIRST token is go test — an inline env-prefixed form (THIRDPARTY_INTEGRATION=1 … go test …) starts with the variable, not go. And separate Bash invocations do not carry env vars forward, so an "export … then go test" recipe is unreliable under a strict tool runtime. Use the single-invocation wrapper scripts/run_vendor_integration.sh <env-file> <pkg> (allowlisted as Bash(bash scripts/run_vendor_integration.sh*)): it parses a gitignored env file as KEY=VALUE data (it never sources it — sourcing would execute shell hidden in the file), validates the gate/sandbox/account vars, refuses a prod target, and fixes -tags=integration -count=1 -timeout=<bounded> -p=<n> -parallel=<n> -v. Extra args are limited to a strict allowlist (-run/-skip/-shuffle + value, -v/-race/-short/-failfast), so neither -count/-timeout/-tags/-p/-parallel nor their -test.count/-test.timeout binary-flag forms, nor -args, can slip through; a package starting with - is refused; the timeout is clamped to [1s, 3600s]; suite concurrency defaults to serial (VENDOR_TEST_PARALLELISM, capped [1,4], so a large fan-out can't exceed the per-test cost budget); and a green run is reported as failure unless at least one test whose name contains the marker (VENDOR_TEST_NAME_MATCH, default Integration) actually PASSED — so an all-skip run (e.g. a destructive tier without INTEGRATION_ALLOW_DESTRUCTIVE=1) or a bad -run pattern never false-greens. Run it from the target repository root (so a relative package like ./internal/... resolves against that repo), invoking it by an absolute path to the installed skill. Calling it by absolute path won't match the relative allowlist entry above — add one for the install path (Bash(bash /path/to/skill/scripts/run_vendor_integration.sh*)). The regression suite under scripts/tests/ is maintainer tooling (python3 -m unittest), intentionally outside this skill's runtime allowlist.

Output Contract

Use the shared output contract in:

• references/common-output-contract.md

References (Load Selectively)

1. Always read: references/common-integration-gate.md — gate design, resolved-host + account validation, degradation levels, skip-vs-fail. Parallel to $api-integration-test's gate (same safety bar, plus vendor rules) — it is a separate file, not shared; edits do not propagate between skills.
2. Always read: references/common-output-contract.md — structured report format. Parallel to $api-integration-test's — a separate file, not shared.
3. Always read when writing test code: references/go-baseline.md — the canonical Go safety helpers; copy them into the test package verbatim (kept token-identical to the regression fixture).
4. Read if authoring new tests or triaging failures: references/checklists.md — when you author or review test code you MUST then score it against that file's §Test Quality Checklist and report the verdict (output-contract field 9): any single Critical FAIL is an overall FAIL, Standard needs ≥4/5, Hygiene ≥3/4.
5. Read if no vendor pattern exists in the repo: references/vendor-examples.md — generic template and run commands