Instruction file imported from CanarysPlayground/Trex-runner-Game (.github/instructions/apitest.instructions.md). Copyright stays with the author.

API Testing Basics

Scope

• Focus on score API behavior in api/server.js.
• Cover API-related tests in tests.

Test Coverage Requirements

• Validate happy path responses for GET and POST score endpoints.
• Validate invalid input handling (non-numeric, negative, empty, malformed).
• Validate boundary behavior (score 0, very high score, repeated same score).
• Validate state behavior (high score updates only when new score is greater).

Test Design Rules

• Arrange tests using clear setup, action, and assertion flow.
• Add at least one assertion per meaningful step.
• Use readable names that describe expected behavior.
• Keep tests isolated and deterministic.

API Assertions

• Check HTTP status code.
• Check response body shape and required fields.
• Check highScore value transitions after POST operations.
• Check error payload for invalid requests.

Failure and Reliability Checks

• Include at least one negative test per endpoint.
• Include at least one boundary test per endpoint.
• Include simple timing/performance sanity check for response completion.

Reporting Format

• Prefer concise bullet lists or small tables for:
  • Endpoint
  • Scenario type (positive, negative, boundary)
  • Expected result
  • Actual result

Tooling Preferences

• Prefer Playwright request testing for API verification in end-to-end flows.
• If unit-level API tests are added, keep selectors and fixtures readable and minimal.