diff --git a/pygmt/tests/test_grdimage.py b/pygmt/tests/test_grdimage.py
index c4658dc38e7..7a29bc0a572 100644
--- a/pygmt/tests/test_grdimage.py
+++ b/pygmt/tests/test_grdimage.py
@@ -78,10 +78,19 @@ def test_grdimage_file():
     condition=gmt_version <= Version("6.1.1"),
 )
 @check_figures_equal()
-def test_grdimage_xarray_shading(grid):
+@pytest.mark.parametrize(
+    "shading",
+    [True, 0.5, "+a30+nt0.8", "@earth_relief_01d_g+d", "@earth_relief_01d_g+a60+nt0.8"],
+)
+def test_grdimage_shading_xarray(grid, shading):
     """
     Test that shading works well for xarray.
-    See https://github.com/GenericMappingTools/pygmt/issues/364
+
+    The ``shading`` can be True, a constant intensity, some modifiers, or
+    a grid with modifiers.
+
+    See https://github.com/GenericMappingTools/pygmt/issues/364 and
+    https://github.com/GenericMappingTools/pygmt/issues/618.
     """
     fig_ref, fig_test = Figure(), Figure()
     kwargs = dict(
@@ -89,7 +98,7 @@ def test_grdimage_xarray_shading(grid):
         frame=True,
         projection="Cyl_stere/6i",
         cmap="geo",
-        shading=True,
+        shading=shading,
     )
 
     fig_ref.grdimage("@earth_relief_01d_g", **kwargs)