Generalize test for multiple backends.

Author: fgoudreault

lib/matplotlib/tests/test_backend_tk.py

@@ -4,18 +4,11 @@
 import platform
 import subprocess
 import sys
-import tempfile
-import warnings
-
-from PIL import Image
 
 import pytest
 
-import matplotlib
 from matplotlib import _c_internal_utils
-from matplotlib.backend_tools import ToolToggleBase
 from matplotlib.testing import subprocess_run_helper
-import matplotlib.pyplot as plt
 
 
 _test_timeout = 60  # A reasonably safe value for slower architectures.
@@ -185,32 +178,6 @@ def test_never_update():
     # checks them.
 
 
-@pytest.mark.backend('TkAgg', skip_on_importerror=True)
-@_isolated_tk_test(success_count=0)
-def test_toolbar_button_la_mode_icon():
-    # test that icon in LA mode can be used for buttons
-    # see GH#25164
-    # tweaking toolbar raises an UserWarning
-    with warnings.catch_warnings():
-        warnings.simplefilter("ignore", UserWarning)
-        matplotlib.rcParams["toolbar"] = "toolmanager"
-
-    # create an icon in LA mode
-    with tempfile.TemporaryDirectory() as tempdir:
-        img = Image.new("LA", (26, 26))
-        tmp_img_path = os.path.join(tempdir, "test_la_icon.png")
-        img.save(tmp_img_path)
-
-        class CustomTool(ToolToggleBase):
-            image = tmp_img_path
-
-        fig = plt.figure()
-        toolmanager = fig.canvas.manager.toolmanager
-        toolbar = fig.canvas.manager.toolbar
-        toolmanager.add_tool("test", CustomTool)
-        toolbar.add_tool("test", "group")
-
-
 @_isolated_tk_test(success_count=2)
 def test_missing_back_button():
     import matplotlib.pyplot as plt

lib/matplotlib/tests/test_backend_tools.py

@@ -1,6 +1,17 @@
+import os
+import subprocess
+import tempfile
+from PIL import Image
+
 import pytest
 
-from matplotlib.backend_tools import ToolHelpBase
+import matplotlib
+from matplotlib.backend_tools import ToolHelpBase, ToolToggleBase
+import matplotlib.pyplot as plt
+from matplotlib.testing import subprocess_run_helper
+from .test_backends_interactive import (
+        _get_testable_interactive_backends, _test_timeout,
+        )
 
 
 @pytest.mark.parametrize('rc_shortcut,expected', [
@@ -18,3 +29,41 @@
 ])
 def test_format_shortcut(rc_shortcut, expected):
     assert ToolHelpBase.format_shortcut(rc_shortcut) == expected
+
+
+def _test_toolbar_button_la_mode_icon_inside_subprocess():
+    matplotlib.rcParams["toolbar"] = "toolmanager"
+    # create an icon in LA mode
+    with tempfile.TemporaryDirectory() as tempdir:
+        img = Image.new("LA", (26, 26))
+        tmp_img_path = os.path.join(tempdir, "test_la_icon.png")
+        img.save(tmp_img_path)
+
+        class CustomTool(ToolToggleBase):
+            image = tmp_img_path
+            description = ""  # gtk3 backend does not allow None
+
+        fig = plt.figure()
+        toolmanager = fig.canvas.manager.toolmanager
+        toolbar = fig.canvas.manager.toolbar
+        toolmanager.add_tool("test", CustomTool)
+        toolbar.add_tool("test", "group")
+
+
+@pytest.mark.parametrize(
+        "env",
+        _get_testable_interactive_backends(),
+        )
+def test_toolbar_button_la_mode_icon(env):
+    # test that icon in LA mode can be used for buttons
+    # see GH#25164
+    try:
+        # run inside subprocess for a self-contained environment
+        proc = subprocess_run_helper(
+            _test_toolbar_button_la_mode_icon_inside_subprocess,
+            timeout=_test_timeout,
+            extra_env=env,
+            )
+    except subprocess.CalledProcessError as err:
+        pytest.fail(
+                f"subprocess failed to test intended behavior: {err.stderr}")