write-tests

name	write-tests
description	Write and run tests for the .NET API following a plan's exact test list and our testing conventions — unit (domain/handlers) and integration (endpoint→DB), exact pass/fail/skip counts, never weakening a test. Use when adding or changing tests under apps/api/tests. Preloaded by the testing-expert agent.
argument-hint	<feature or plan path>
allowed-tools	Read, Glob, Grep, Edit, Write, Bash, Skill, mcp__serena__initial_instructions, mcp__serena__get_symbols_overview, mcp__serena__find_symbol, mcp__serena__find_referencing_symbols, mcp__serena__find_declaration, mcp__serena__find_implementations, mcp__serena__search_for_pattern, mcp__serena__get_diagnostics_for_file, mcp__serena__list_dir, mcp__serena__find_file, mcp__serena__create_text_file, mcp__serena__replace_symbol_body, mcp__serena__insert_after_symbol, mcp__serena__insert_before_symbol, mcp__serena__replace_content, mcp__serena__rename_symbol, mcp__serena__safe_delete_symbol

Serena MCP is mandatory for C# code. First call mcp__serena__initial_instructions to load the Serena tool manual, then use the Serena tools for ALL .cs reading / searching / navigation / creation / editing — prefer symbol navigation (get_symbols_overview / find_symbol / find_referencing_symbols) over whole-file reads. Native Edit/Write on .cs is hook-blocked (the TS/React frontend uses the native tools).

Write tests ({{ProductName}} .NET API)

The procedure for authoring tests. C# (.cs) test files go through Serena.

⚠ Test stack is pending Dan's approval. Test libraries (xUnit / NUnit / TUnit, NSubstitute / Moq, FluentAssertions, Testcontainers for PostgreSQL, Vitest / Playwright) are library decisions for Dan — do not adopt one silently. Until a stack is approved, follow the stack the plan specifies; if the plan names an unapproved library, STOP and flag it.

Scopes

• Unit — domain (factory guard clauses + invariant throws + behaviour methods), Kommand handlers (with collaborators substituted), the Result<T>/Error mapping. Fast, no real I/O.
• Integration — endpoint → handler → real PostgreSQL (via Testcontainers once approved), asserting the HTTP contract (status + ProblemDetails on failure) and persistence. Honor the tenancy invariant in fixtures.

Procedure

1. Implement the plan's "Exact test list" verbatim — each named test asserts exactly what the plan says it guards (one focused assertion per test). Mirror the feature folder structure under apps/api/tests.
2. Write the .cs test files via Serena.
3. Run the suite and report EXACT counts — e.g. passed 42 / failed 0 / skipped 1, never "tests pass".
4. Never weaken, skip, disable, or delete a test (or disable an analyzer) to get green. A failing test that reveals a real defect is a finding — report it; do not paper over it.
5. Note any "Known coverage gap" the harness cannot verify.

Conventions

• Test names describe the scenario (the [tests/**.cs] editorconfig drops the Async suffix requirement).
• No coverage-percentage / CRAP gate unless the plan asks for one.
• Tests assert against our contracts: Result<T>/ProblemDetails, tenancy, async discipline.