# Requirement Traceability

This document shows how requirements map to tests via pytest markers and docstrings, plus how to visualize coverage.

## Conventions

- Requirement IDs: `REQ-xxx`
- Use markers in tests: `@pytest.mark.req_001`, `@pytest.mark.req_002`, etc.
- Include readable requirement list in the test docstring under `Requirements:`

## Example

```python
@pytest.mark.req_001
@pytest.mark.req_003
"""
Title: Mock LIN Interface - Send/Receive Echo Test
Requirements: REQ-001, REQ-003
"""
```

## Mermaid: Requirement → Tests map

Note: This is illustrative; maintain it as your suite grows.

```mermaid
flowchart LR
  R1[REQ-001: LIN Basic Ops]
  R2[REQ-002: Master Request/Response]
  R3[REQ-003: Frame Validation]
  R4[REQ-004: Timeout Handling]

  T1[test_mock_send_receive_echo]
  T2[test_mock_request_synthesized_response]
  T3[test_mock_receive_timeout_behavior]
  T4[test_mock_frame_validation_boundaries]

  R1 --> T1
  R3 --> T1
  R2 --> T2
  R4 --> T3
  R1 --> T4
  R3 --> T4
```

## Generating a live coverage artifact (optional)

You can extend `conftest_plugin.py` to emit a JSON file with requirement-to-test mapping at the end of a run by scanning markers and docstrings. This can fuel dashboards or CI gates.

Suggested JSON shape:

```json
{
  "requirements": {
    "REQ-001": ["tests/test_smoke_mock.py::TestMockLinInterface::test_mock_send_receive_echo", "..."]
  },
  "uncovered": ["REQ-010", "REQ-012"]
}
```