matplotlib · oscargus · Aug 16, 2023 · Aug 15, 2023
diff --git a/lib/mpl_toolkits/mplot3d/art3d.py b/lib/mpl_toolkits/mplot3d/art3d.py
@@ -905,7 +905,7 @@ def __init__(self, verts, *args, zsort='average', shade=False,
                kwargs['edgecolors'] = _shade_colors(
                    edgecolors, normals, lightsource
                )
-            if facecolors is None and edgecolors in None:
+            if facecolors is None and edgecolors is None:
                raise ValueError(
                    "You must provide facecolors, edgecolors, or both for "
                    "shade to work.")

diff --git a/lib/mpl_toolkits/mplot3d/tests/test_axes3d.py b/lib/mpl_toolkits/mplot3d/tests/test_axes3d.py
@@ -2260,3 +2260,13 @@ def test_surface3d_zsort_inf():

    ax.plot_surface(x, y, z, cmap='jet')
    ax.view_init(elev=45, azim=145)
+
+
+def test_Poly3DCollection_init_value_error():
+    # smoke test to ensure the input check works
+    # GH#26420
+    with pytest.raises(ValueError,
+                       match='You must provide facecolors, edgecolors, '
+                        'or both for shade to work.'):
+        poly = np.array([[0, 0, 1], [0, 1, 1], [0, 0, 0]], float)
+        c = art3d.Poly3DCollection([poly], shade=True)