Fixes the issue 23770 and adds a test in test_backends_interactive.py

turnipseason · turnipseason · commit ccb4e7e845fa · 2023-05-12T13:34:32.000+03:00
diff --git a/lib/matplotlib/pyplot.py b/lib/matplotlib/pyplot.py
@@ -202,9 +202,12 @@ def install_repl_displayhook():
 
     from IPython.core.pylabtools import backend2gui  # type: ignore
     # trigger IPython's eventloop integration, if available
-    ipython_gui_name = backend2gui.get(get_backend())
-    if ipython_gui_name:
-        ip.enable_gui(ipython_gui_name)
+    try:
+        ipython_gui_name = backend2gui.get(get_backend())
+        if ipython_gui_name:
+            ip.enable_gui(ipython_gui_name)
+    except NotImplementedError as err:
+        raise ImportError('Fallback to a different backend.') from err
 
 
 def uninstall_repl_displayhook():
@@ -389,7 +392,6 @@ def draw_if_interactive():
     for func_name in ["new_figure_manager", "draw_if_interactive", "show"]:
         globals()[func_name].__signature__ = inspect.signature(
             getattr(backend_mod, func_name))
-
     # Need to keep a global reference to the backend for compatibility reasons.
     # See https://github.com/matplotlib/matplotlib/issues/6092
     matplotlib.backends.backend = newbackend
@@ -398,7 +400,11 @@ def draw_if_interactive():
 
     # make sure the repl display hook is installed in case we become
     # interactive
-    install_repl_displayhook()
+    try:
+        install_repl_displayhook()
+    except ImportError as err:
+        _log.warning(str(err))
+        raise ImportError
 
 
 def _warn_if_gui_out_of_main_thread():
diff --git a/lib/matplotlib/tests/test_backends_interactive.py b/lib/matplotlib/tests/test_backends_interactive.py
@@ -536,6 +536,19 @@ def test_blitting_events(env):
     assert 0 < ndraws < 5
 
 
+def test_fallback_to_different_backend():
+    import subprocess
+    # Runs the process that caused the GH issue 23770
+    # making sure that this doesn't crash
+    # since we're supposed to be switching to a different backend instead.
+    response = subprocess.run(["python", "-c",
+                                "import IPython.core.interactiveshell as ipsh; "
+                                "ipsh.InteractiveShell.instance(); "
+                                "import matplotlib.pyplot; "
+                                "matplotlib.pyplot.figure()"], check=True)
+    assert response != subprocess.CalledProcessError
+
+
 # The source of this function gets extracted and run in another process, so it
 # must be fully self-contained.
 def _test_figure_leak():
