feat: Add health_check() method to OllamaAdapter

[gauravxthakur]

Description

Implemented the async health_check() method for OllamaAdapter to verify server availability.

Related Issue

#36
Fixes #36

Type of Change

• New feature (non-breaking change which adds functionality)

Changes Made

• Added health_check() to OllamaAdapter using the /api/tags endpoint.
• Used httpx.RequestError to handle connection failures, following the existing HTTPAdapter pattern.
• Added 3 unit tests in tests/test_adapters.py covering: server success (200), server failure (500), and unreachable host (wrong port).

Testing

Test Configuration

• Python Version: 3.13.7
• OS: Windows 11

Tests Added/Modified

• Unit tests added/updated
• All tests pass locally
• Test coverage maintained or improved

Manual Testing Steps

1. Run py -m pytest tests/test_adapters.py -v to verify all 33 adapter tests pass.
2. Run py -m mypy evalview/adapters/ollama_adapter.py to ensure type safety.

Checklist

Code Quality

• My code follows the project's style guidelines
• I have run mypy and fixed any type errors
• I have performed a self-review of my own code

Documentation

• I have added docstrings to new functions/classes

Testing

• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

Dependencies

• I have checked that no new dependencies were added unnecessarily

Screenshots

Additional Notes

The issue tips suggested using aiohttp. However, after reviewing the current implementation of HTTPAdapter.health_check() and pyproject.toml, I found the project is standardized on httpx. I used httpx to maintain consistency with the existing codebase.

Reviewer Notes

Please verify that the transition to httpx for this adapter aligns with the project's long-term direction, as it differs from the suggestion in the issue description.

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By submitting this pull request, I confirm that:

• I have read and followed the CONTRIBUTING.md guidelines
• I agree to the project's CODE_OF_CONDUCT.md
• My contribution is my own work and I have the right to contribute it

[hidai25]

Hey @gauravxthakur great contribution!

The implementation is clean and correct — /api/tags is the right endpoint,
httpx.RequestError correctly catches both connection errors and timeouts, and the httpx
decision over aiohttp was exactly right. Good instinct to check the existing codebase
rather than follow the issue suggestion blindly.

Two tiny nitpicks (not blocking):

• test_health_check_failure could add assert_called_once_with like the success test
  does, just for consistency
• A test for httpx.TimeoutException would be nice since timeouts are a common Ollama
  failure mode

Neither is a blocker and merging as-is. Thanks for the thorough PR description and for
running mypy. Looking forward to more contributions!

[gauravxthakur]

Thanks @hidai25 for the feedback and for merging!

Really glad the httpx decision aligned with the project's direction. Noted on the assert_called_once_with and the TimeoutException test. I'll make sure to include those patterns in my next PR.