Generate Mock

Purpose

Provide deterministic, conventional mocks that match the test framework in use, with realistic synthetic return values and no accidental network calls.

When to Invoke

• A unit test needs to isolate a service dependency.
• A frontend component test needs to mock a fetch client.
• An integration test needs an MSW handler for an outbound call.

When NOT to Invoke

• For contract tests (use /skill-api-contract-test).
• For real integration tests where the dependency should actually run.
• For production code stubs.

Inputs

• target: symbol or module path to mock.
• framework: pytest, vitest, or msw.
• scenario (optional): success (default), error, or empty.

Procedure

1. Resolve the target and read its signature(s).
2. For pytest: generate a fixture under api/tests/fixtures/ that patches the symbol with unittest.mock.MagicMock and sets a return value matching the Pydantic model.
3. For vitest: generate a vi.mock(...) block with a typed return value drawn from the existing builder or a literal.
4. For msw: generate a handler under frontend/src/test-utils/msw/ returning a synthetic response.
5. Apply the scenario to choose return shape:
   • success → fully populated valid response.
   • error → raises / returns 4xx/5xx with a synthetic error body.
   • empty → empty list or null result.
6. Write the mock to the conventional location.

Outputs

• New mock file at the conventional location, imported from the nearest test-utils barrel if one exists.
• Summary of the mocked symbol, framework, scenario, and return shape.

Safety

• Never invokes the real dependency during generation.
• Never embeds real credentials or tokens in mock payloads.
• Never mocks security-sensitive modules (auth, audit logging) without a reminder that the mock must not be reused in integration tests.
• FedRAMP: all mock payloads use synthetic IDs and @example.test emails.

Examples

Example 1 — Pytest. Mock OpportunitySearchClient.query with a 3-item success payload.

Example 2 — Vitest. Mock fetchOpportunities to return an empty list, exercising the empty-state component.

Example 3 — MSW. Add a handler for GET /v1/opportunities/search returning a 500 to test error UI.

Related

• .cursor/skills/skill-generate-factory/ — factories for shared return values.
• .cursor/skills/skill-api-contract-test/ — contract tests, not mocks.