test: add 3D scatter test for cmap update (#30062)

MiniX16 · web-flow · commit 35c54819e8ff · 2025-05-18T14:59:24.000+02:00
diff --git a/lib/matplotlib/tests/test_collections.py b/lib/matplotlib/tests/test_collections.py
@@ -492,6 +492,28 @@ def test_polycollection_close():
     ax.set_ylim3d(0, 4)
 
 
+@check_figures_equal(extensions=["png"])
+def test_scalarmap_change_cmap(fig_test, fig_ref):
+    # Ensure that changing the colormap of a 3D scatter after draw updates the colors.
+
+    x, y, z = np.array(list(itertools.product(
+        np.arange(0, 5, 1),
+        np.arange(0, 5, 1),
+        np.arange(0, 5, 1)
+    ))).T
+    c = x + y
+
+    # test
+    ax_test = fig_test.add_subplot(111, projection='3d')
+    sc_test = ax_test.scatter(x, y, z, c=c, s=40, cmap='jet')
+    fig_test.canvas.draw()
+    sc_test.set_cmap('viridis')
+
+    # ref
+    ax_ref = fig_ref.add_subplot(111, projection='3d')
+    ax_ref.scatter(x, y, z, c=c, s=40, cmap='viridis')
+
+
 @image_comparison(['regularpolycollection_rotate.png'], remove_text=True)
 def test_regularpolycollection_rotate():
     xx, yy = np.mgrid[:10, :10]
