testing

Skill: Testing

Description

Write, run, or fix tests for the Blog API using pytest and httpx.

When to Use

Trigger this skill when the user says:

• "write tests", "add tests", "test this"
• "tests are failing", "fix the tests"
• "what's the test coverage?"
• "/test"

Instructions

When WRITING new tests

1. Locate the correct test file. Tests live in arc/tests/. Match the source file:

   • arc/routes/posts.py → arc/tests/test_posts.py
   • arc/services/post_service.py → arc/tests/test_post_service.py

2. Use the shared test fixtures from conftest.py. Never create a new database or app instance inline — use the fixtures:

   def test_something(client, db_session):
       ...
   

3. Follow the Arrange / Act / Assert pattern.

   def test_create_post_returns_201(client):
       # Arrange
       payload = {"title": "Hello", "body": "World", "author_id": 1}
   
       # Act
       response = client.post("/posts", json=payload)
   
       # Assert
       assert response.status_code == 201
       assert response.json()["title"] == "Hello"
   

4. Name tests descriptively. Format: test_<what>_<expected_result>

   • Good: test_get_post_returns_404_when_not_found
   • Bad: test_post, test_1

5. Test the sad path too. For every happy-path test, add at least one test for the failure case (missing field, wrong type, unauthorized, not found).

When FIXING failing tests

1. Read the full error output carefully before changing anything.
2. Check if the test is wrong (asserting the wrong thing) or the code is wrong.
3. If the schema or route signature changed, update the test to match — but note it in your reply.
4. Never delete a test to make it pass.

When RUNNING tests

Run: pytest arc/tests/ -v --tb=short

For a single file: pytest arc/tests/test_posts.py -v

For coverage: pytest arc/tests/ --cov=arc --cov-report=term-missing

Output Format

When writing tests, show the complete test function(s), then say: "Run with: pytest arc/tests/<filename>.py::test_<name> -v"