Add tests of do_3d_projection deprecation

Co-authored-by: Thomas A Caswell <[email protected]>

Author: jakelishman

lib/mpl_toolkits/tests/test_mplot3d.py

@@ -1711,3 +1711,63 @@ def test_view_init_vertical_axis(
         tickdir_expected = tickdirs_expected[i]
         tickdir_actual = axis._get_tickdir()
         np.testing.assert_array_equal(tickdir_expected, tickdir_actual)
+
+
+def test_do_3d_projection_renderer_deprecation_warn_on_argument():
+    """
+    Test that an external artist with an old-style calling convention raises
+    a suitable deprecation warning.
+    """
+    class DummyPatch(art3d.Patch3D):
+        def do_3d_projection(self, renderer):
+            return 0
+
+        def draw(self, renderer):
+            pass
+
+    fig = plt.figure()
+    ax = fig.add_subplot(111, projection='3d')
+    artist = DummyPatch()
+    ax.add_artist(artist)
+
+    match = r"The 'renderer' parameter of do_3d_projection\(\) was deprecated"
+    with pytest.warns(MatplotlibDeprecationWarning, match=match):
+        fig.canvas.draw()
+
+
+def test_do_3d_projection_renderer_deprecation_nowarn_on_optional_argument():
+    """
+    Test that an external artist with a calling convention compatible with
+    both v3.3 and v3.4 does not raise a deprecation warning.
+    """
+    class DummyPatch(art3d.Patch3D):
+        def do_3d_projection(self, renderer=None):
+            return 0
+
+        def draw(self, renderer):
+            pass
+
+    fig = plt.figure()
+    ax = fig.add_subplot(111, projection='3d')
+    artist = DummyPatch()
+    ax.add_artist(artist)
+    fig.canvas.draw()
+
+
+def test_do_3d_projection_renderer_deprecation_nowarn_on_no_argument():
+    """
+    Test that an external artist with a calling convention compatible with
+    only v3.4 does not raise a deprecation warning.
+    """
+    class DummyPatch(art3d.Patch3D):
+        def do_3d_projection(self):
+            return 0
+
+        def draw(self, renderer):
+            pass
+
+    fig = plt.figure()
+    ax = fig.add_subplot(111, projection='3d')
+    artist = DummyPatch()
+    ax.add_artist(artist)
+    fig.canvas.draw()