Convert tests from unittest to pytest format (#76)

- Convert df_test.py from unittest to pytest with fixtures and markers
- Convert df_integrationtest.py to pytest format with integration
markers
- Update sql_test.py with pytest fixtures and modern assertions
- Add pytest configuration to pyproject.toml
- Format all test files with pyink
- Add @pytest.mark.unit, @pytest.mark.integration, @pytest.mark.gcs
markers
- Maintain existing project structure and Google-style docstrings

Tests now use modern pytest features while respecting project
guidelines.

---------

Signed-off-by: Rohan Disa <[email protected]>
Co-authored-by: Alex Merose <[email protected]>

Author: RohanDisa

.github/workflows/ci.yml

@@ -48,4 +48,4 @@ jobs:
       - name: Install xarray_sql
         run: uv sync --dev
       - name: Run unit tests
-        run: uv run pytest
+        run: uv run pytest -m "not integration"

perf_tests/compute_air.py

@@ -3,9 +3,9 @@
 import xarray as xr
 import xarray_sql as qr
 
-if __name__ == '__main__':
-  air = xr.tutorial.open_dataset('air_temperature')
-  chunks = {'time': 240}
+if __name__ == "__main__":
+  air = xr.tutorial.open_dataset("air_temperature")
+  chunks = {"time": 240}
   air = air.chunk(chunks)
 
   df = qr.read_xarray(air).compute()