Add unit tests for write_netcdf()

Author: xylar

conda_package/tests/test_io.py

@@ -0,0 +1,60 @@
+import os
+import subprocess
+
+import numpy as np
+import pytest
+import xarray as xr
+
+from mpas_tools.io import write_netcdf
+
+from .util import get_test_data_file
+
+TEST_MESH = get_test_data_file('mesh.QU.1920km.151026.nc')
+
+
+@pytest.mark.skipif(
+    not os.path.exists(TEST_MESH), reason='Test mesh not available'
+)
+def test_write_netcdf_basic(tmp_path):
+    ds = xr.open_dataset(TEST_MESH)
+    out_file = tmp_path / 'test_basic.nc'
+    write_netcdf(ds, str(out_file))
+    ds2 = xr.open_dataset(out_file)
+    # Should have same dimensions and variables
+    assert set(ds.dims) == set(ds2.dims)
+    for var in ds.data_vars:
+        assert var in ds2.data_vars
+    ds2.close()
+
+
+@pytest.mark.skipif(
+    not os.path.exists(TEST_MESH), reason='Test mesh not available'
+)
+def test_write_netcdf_cdf5_format(tmp_path):
+    ds = xr.open_dataset(TEST_MESH)
+    out_file = tmp_path / 'test_cdf5.nc'
+    write_netcdf(ds, str(out_file), format='NETCDF3_64BIT_DATA')
+    # Use ncdump -k to check format
+    result = subprocess.run(
+        ['ncdump', '-k', str(out_file)],
+        capture_output=True,
+        text=True,
+        check=True,
+    )
+    # Should be cdf5 for NETCDF3_64BIT_DATA
+    assert result.stdout.strip() == 'cdf5'
+
+
+def test_write_netcdf_int64_conversion_and_attr(tmp_path):
+    # Create a dataset with int64 variable and an attribute
+    arr = np.array([1, 2, 3], dtype=np.int64)
+    ds = xr.Dataset({'foo': (('x',), arr)})
+    ds['foo'].attrs['myattr'] = 'testattr'
+    out_file = tmp_path / 'test_int64.nc'
+    write_netcdf(ds, str(out_file))
+    ds2 = xr.open_dataset(out_file)
+    # Should be int32, not int64
+    assert ds2['foo'].dtype == np.int32
+    # Attribute should be preserved
+    assert ds2['foo'].attrs['myattr'] == 'testattr'
+    ds2.close()