add samples.lfric warn test coverage

tests/samples/test_lfric.py

@@ -0,0 +1,31 @@
+"""Unit-tests for :func:`geovista.samples.lfric`."""
+from __future__ import annotations
+
+import pytest
+
+from geovista.samples import LFRIC_RESOLUTION, lfric
+
+
+def test_resolution_warning(mocker):
+    """Test warning raised of invalid cubed-sphere resolution request."""
+    processor = mocker.sentinel.processor
+    _ = mocker.patch("pooch.Decompress", return_value=processor)
+    resource = mocker.sentinel.resource
+    _ = mocker.patch("geovista.cache.CACHE.fetch", return_value=resource)
+    mesh = mocker.sentinel.mesh
+    _ = mocker.patch("pyvista.read", return_value=mesh)
+    bad = "r24"
+    wmsg = f"geovista detected unknown LFRic cubed-sphere resolution {bad!r}"
+    with pytest.warns(UserWarning, match=wmsg):
+        result = lfric(resolution=bad)
+
+    import pooch
+    import pyvista as pv
+
+    from geovista.cache import CACHE
+
+    fname = f"lfric_{LFRIC_RESOLUTION}.vtk"
+    pooch.Decompress.assert_called_once_with(method="auto", name=fname)
+    CACHE.fetch.assert_called_once_with(f"mesh/{fname}.bz2", processor=processor)
+    pv.read.assert_called_once_with(resource)
+    assert result == mesh