Use svg instead of png for font manager memory leak test

ksunden · ksunden · commit 80415168522b · 2023-03-28T16:01:03.000-05:00
Some versions of Pillow (notably v9.2.0 is what I had installed) trigger a failure on this test that looks the same as if it was a failure on our own part. v9.4.0 of Pillow does not have the same behavior, hence CI does not catch it.

This changes to svg to avoid the external dependency triggering the failure. The fontmanager lookup that we are explicitly trying to test here does still trigger for svg output, but the pillow generated one does not
diff --git a/lib/matplotlib/tests/test_font_manager.py b/lib/matplotlib/tests/test_font_manager.py
@@ -340,7 +340,7 @@ def inner():
         with BytesIO() as out:
             with warnings.catch_warnings():
                 warnings.filterwarnings('ignore')
-                fig.savefig(out, format='png')
+                fig.savefig(out, format='svg')
 
     inner()
 

Original file line number	Diff line number	Diff line change
`@@ -340,7 +340,7 @@ def inner():`
`340`	`340`	`with BytesIO() as out:`
`341`	`341`	`with warnings.catch_warnings():`
`342`	`342`	`warnings.filterwarnings('ignore')`
`343`		`- fig.savefig(out, format='png')`
	`343`	`+ fig.savefig(out, format='svg')`
`344`	`344`
`345`	`345`	`inner()`
`346`	`346`