End-to-End Python Hook Tests

Part of #7435 — Multi-Language Hook Support

User Story

As a developer maintaining the hook system, I want comprehensive end-to-end tests that verify the full Python hook lifecycle so regressions are caught automatically.

Solution Approach

Test scenario 1 — Happy path:

1. Create test project with:
   • azure.yaml with preprovision Python hook
   • scripts/setup.py that reads an env var and writes it to a marker file
   • scripts/requirements.txt with a simple dependency
2. Verify:
   • Hook detected as Python language hook
   • Virtual environment created (.venv exists)
   • Dependencies installed
   • Script executes successfully
   • Environment variables available to script
   • Exit code 0

Test scenario 2 — Auto-detect vs explicit:

• Test with run: scripts/setup.py (auto-detect from .py)
• Test with run: scripts/setup + language: python (explicit)
• Both should execute identically

Test scenario 3 — Error cases:

• Missing Python runtime → clear error with install URL
• Missing script file → clear error
• Script exits non-zero → error propagated
• continueOnError: true + failing script → no error, continues

Test scenario 4 — Service-level hooks:

• Python hook defined under a service, not project root
• Verify project discovery scoped to service directory

Location: Follow existing patterns in test/functional/testdata/samples/ for fixtures, test/functional/ or pkg/ext/ for test files.

Files: test/functional/ or pkg/ext/hooks_runner_test.go (NEW/MODIFY), test fixtures

Acceptance Criteria

• Tests pass on CI (requires Python installed in CI environment)
• Validates complete flow: YAML → language detection → venv → install → execute → output
• Tests both success and error paths
• Tests environment variable passing
• Tests both project-level and service-level hooks
• Tests auto-detect and explicit language: field

References

• Contributes to: Multi-Language Hook Support: Python, JavaScript, TypeScript, .NET #7435