add geovista.crs.has_wkt (#440)

src/geovista/crs.py

@@ -21,6 +21,7 @@
     "WGS84",
     "from_wkt",
     "get_central_meridian",
+    "has_wkt",
     "projected",
     "set_central_meridian",
     "to_wkt",
@@ -59,7 +60,7 @@ def from_wkt(mesh: pv.PolyData) -> CRS:
     """
     crs = None
 
-    if GV_FIELD_CRS in mesh.field_data:
+    if has_wkt(mesh):
         wkt = str(mesh.field_data[GV_FIELD_CRS][0])
         crs = CRS.from_wkt(wkt)
 
@@ -100,6 +101,27 @@ def get_central_meridian(crs: CRS) -> float | None:
     return result
 
 
+def has_wkt(mesh: pv.PolyData) -> bool:
+    """Determine whether the provided mesh has a CRS serialized as WKT attached.
+
+    Parameters
+    ----------
+    mesh : PolyData
+        The mesh to be inspected for a serialized CRS.
+
+    Returns
+    -------
+    bool
+        Whether the mesh has a CRS serialized as WKT attached.
+
+    Notes
+    -----
+    .. versionadded:: 0.4.0
+
+    """
+    return GV_FIELD_CRS in mesh.field_data
+
+
 def projected(mesh: pv.PolyData) -> bool:
     """Determine if the mesh is a planar projection.
 

tests/conftest.py

@@ -3,6 +3,7 @@
 
 import numpy as np
 import pytest
+import pyvista as pv
 
 from geovista.bridge import Transform
 from geovista.crs import WGS84
@@ -68,6 +69,12 @@ def lfric_sst():
     return mesh
 
 
+@pytest.fixture()
+def sphere():
+    """Fixture to provide a pyvista sphere mesh."""
+    return pv.Sphere()
+
+
 @pytest.fixture
 def wgs84_wkt():
     """Fixture for generating WG284 CRS WKT as a string."""

tests/core/test_slice_lines.py

@@ -32,7 +32,7 @@ def test_projected_fail(mesh):
         _ = slice_lines(mesh)
 
 
-@pytest.mark.parametrize("mesh", [pv.Sphere(), lam_uk(), lfric()])
+@pytest.mark.parametrize("mesh", [pv.Cube(), lam_uk(), lfric()])
 def test_no_lines(mesh):
     """Test nop slicing mesh with no lines."""
     result = slice_lines(mesh)

tests/crs/test_has_wkt.py

@@ -0,0 +1,14 @@
+"""Unit-test for :func:`geovista.crs.has_wkt`."""
+from __future__ import annotations
+
+import pytest
+
+from geovista.crs import has_wkt
+
+
+@pytest.mark.parametrize("mesh, expected", [("sphere", False), ("lfric", True)])
+def test(mesh, expected, request):
+    """Test mesh wkt serialization availability."""
+    mesh = request.getfixturevalue(mesh)
+    result = has_wkt(mesh)
+    assert result is expected

tests/crs/test_projected.py

@@ -4,7 +4,7 @@
 from pyproj import CRS
 import pyvista as pv
 
-from geovista.crs import WGS84, projected, to_wkt
+from geovista.crs import WGS84, has_wkt, projected, to_wkt
 
 
 def test_planar__no_crs():
@@ -20,15 +20,14 @@ def test_planer__with_crs():
     assert not projected(mesh)
 
 
-def test_non_planar__no_crs():
+def test_non_planar__no_crs(sphere):
     """Test that the mesh is not projected."""
-    mesh = pv.Sphere()
-    assert not projected(mesh)
+    assert not projected(sphere)
 
 
-def test_non_planer__with_crs():
+def test_non_planer__with_crs(sphere):
     """Test that the mesh CRS is used over the geometry heuristic."""
-    mesh = pv.Sphere()
+    assert has_wkt(sphere) is False
     crs = CRS.from_user_input("+proj=eqc")
-    to_wkt(mesh, crs)
-    assert projected(mesh)
+    to_wkt(sphere, crs)
+    assert projected(sphere)

tests/crs/test_to_wkt.py

@@ -1,18 +1,15 @@
 """Unit-tests for :func:`geovista.crs.to_wkt`."""
 from __future__ import annotations
 
-import pyvista as pv
-
 from geovista.common import GV_FIELD_CRS
 from geovista.crs import WGS84, from_wkt, to_wkt
 
 
-def test():
+def test(sphere):
     """Test OGC WKT serialization of CRS on mesh."""
-    mesh = pv.Sphere()
     crs = WGS84
-    to_wkt(mesh, crs)
-    assert GV_FIELD_CRS in mesh.field_data
+    to_wkt(sphere, crs)
+    assert GV_FIELD_CRS in sphere.field_data
     wkt = WGS84.to_wkt()
-    assert mesh.field_data[GV_FIELD_CRS] == wkt
-    assert from_wkt(mesh) == WGS84
+    assert sphere.field_data[GV_FIELD_CRS] == wkt
+    assert from_wkt(sphere) == WGS84