contours: handle infinite nan coords

xrspatial/contour.py

@@ -66,8 +66,9 @@ def _marching_squares_kernel(data, level, seg_rows, seg_cols, seg_count):
             bl = data[r + 1, c]
             br = data[r + 1, c + 1]
 
-            # Skip quads with any NaN corner.
-            if tl != tl or tr != tr or bl != bl or br != br:
+            # Skip quads with any non-finite corner (NaN or +/-inf).
+            if not (np.isfinite(tl) and np.isfinite(tr) and
+                    np.isfinite(bl) and np.isfinite(br)):
                 continue
 
             # Build 4-bit case index.

xrspatial/tests/test_contour.py

@@ -538,18 +538,11 @@ def test_inf_far_level_no_crossing(self):
             assert np.isfinite(coords).all(), (
                 "level 0.5 ring should not include the inf quad")
 
-    @pytest.mark.xfail(
-        reason="contours() emits NaN coordinates near an inf corner; "
-               "see https://github.com/xarray-contrib/xarray-spatial/"
-               "issues/2704",
-        strict=True,
-    )
     def test_inf_corner_no_nan_coords(self):
         """A finite level near a +inf cell must not leak NaN coordinates.
 
-        The NaN-skip guard in the kernel uses ``x != x`` which does not
-        catch infinity, so the inf quad is interpolated and produces NaN.
-        Tracked as a source bug in #2704.
+        Regression for #2704: the NaN-skip guard in the kernel used ``x != x``
+        which does not catch infinity; fixed by using ``np.isfinite``.
         """
         data = self._inf_peak(np.inf)
         agg = create_test_raster(data, backend='numpy')
@@ -558,21 +551,40 @@ def test_inf_corner_no_nan_coords(self):
             assert np.isfinite(coords).all(), (
                 f"non-finite coordinate in contour at level {level}: {coords}")
 
-    @pytest.mark.xfail(
-        reason="contours() emits NaN coordinates near a -inf corner; "
-               "see https://github.com/xarray-contrib/xarray-spatial/"
-               "issues/2704",
-        strict=True,
-    )
     def test_neg_inf_corner_no_nan_coords(self):
-        """Same NaN leak for a -inf corner. Tracked in #2704."""
+        """A finite level near a -inf cell must not leak NaN coordinates.
+
+        Regression for #2704: same fix as test_inf_corner_no_nan_coords.
+        """
         data = self._inf_peak(-np.inf)
         agg = create_test_raster(data, backend='numpy')
         result = contours(agg, levels=[0.5])
         for level, coords in result:
             assert np.isfinite(coords).all(), (
                 f"non-finite coordinate in contour at level {level}: {coords}")
 
+    def test_mixed_inf(self):
+        """Multiple infinities of opposite signs must not produce NaN."""
+        data = np.array([
+            [0., 0., 0., 0., 0.],
+            [0., np.inf, 1., -np.inf, 0.],
+            [0., 1., 1., 1., 0.],
+            [0., -np.inf, 1., np.inf, 0.],
+            [0., 0., 0., 0., 0.],
+        ], dtype=np.float64)
+        agg = create_test_raster(data, backend='numpy')
+        result = contours(agg, levels=[0.5])
+        for level, coords in result:
+            assert np.isfinite(coords).all(), \
+                f"Non-finite coordinates found at level {level}"
+
+    def test_all_inf_quad(self):
+        """A 2x2 raster with all corners infinite produces no contours."""
+        data = np.full((2, 2), np.inf, dtype=np.float64)
+        agg = create_test_raster(data, backend='numpy')
+        result = contours(agg, levels=[1.0])
+        assert result == []
+
 
 # ---------------------------------------------------------------------------
 # CRS propagation to GeoDataFrame output (#2704 audit, Cat 5)