Backport PR #25339: Disable discarded animation warning on save

tacaswell · meeseeksmachine · commit d526148038fc · 2023-03-02T17:34:52.000Z
diff --git a/lib/matplotlib/animation.py b/lib/matplotlib/animation.py
@@ -992,6 +992,15 @@ def func(current_frame: int, total_frames: int) -> Any
         is a `.MovieWriter`, a `RuntimeError` will be raised.
         """
 
+        all_anim = [self]
+        if extra_anim is not None:
+            all_anim.extend(anim for anim in extra_anim
+                            if anim._fig is self._fig)
+
+        # Disable "Animation was deleted without rendering" warning.
+        for anim in all_anim:
+            anim._draw_was_started = True
+
         if writer is None:
             writer = mpl.rcParams['animation.writer']
         elif (not isinstance(writer, str) and
@@ -1030,11 +1039,6 @@ def func(current_frame: int, total_frames: int) -> Any
         if metadata is not None:
             writer_kwargs['metadata'] = metadata
 
-        all_anim = [self]
-        if extra_anim is not None:
-            all_anim.extend(anim for anim in extra_anim
-                            if anim._fig is self._fig)
-
         # If we have the name of a writer, instantiate an instance of the
         # registered class.
         if isinstance(writer, str):
diff --git a/lib/matplotlib/tests/test_animation.py b/lib/matplotlib/tests/test_animation.py
@@ -514,5 +514,5 @@ def test_movie_writer_invalid_path(anim):
     else:
         match_str = re.escape("[Errno 2] No such file or directory: '/foo")
     with pytest.raises(FileNotFoundError, match=match_str):
-        _ = anim.save("/foo/bar/aardvark/thiscannotreallyexist.mp4",
-                      writer=animation.FFMpegFileWriter())
+        anim.save("/foo/bar/aardvark/thiscannotreallyexist.mp4",
+                  writer=animation.FFMpegFileWriter())
