Fix tests on Python 3.15 (matplotlib#31784)

* Fix test_RcParams_class on Python 3.15

The `repr` for dictionaries now wraps at the braces. For simplicitly,
apply that on older versions as well. Also, shorten the list so it
doesn't wrap and need any additional work.

* TST: Ignore a new fork deprecation warning in Python 3.15

---------

Co-authored-by: Lumir Balhar <lbalhar@redhat.com>

Author: scottshambaugh

lib/matplotlib/tests/test_font_manager.py

@@ -286,6 +286,9 @@ def _model_handler(_):
                     reason='emscripten does not support subprocesses')
 @pytest.mark.skipif(not hasattr(os, "register_at_fork"),
                     reason="Cannot register at_fork handlers")
+# Python 3.15+ raises DeprecationWarning for fork in multi-threaded process
+@pytest.mark.filterwarnings("ignore:.*multi-threaded.*fork.*:DeprecationWarning")
+@pytest.mark.filterwarnings("ignore:.*multi-threaded.*fork.*:RuntimeWarning")
 def test_fork():
     _model_handler(0)  # Make sure the font cache is filled.
     ctx = multiprocessing.get_context("fork")

lib/matplotlib/tests/test_rcparams.py

@@ -73,32 +73,34 @@ def func():
 
 
 def test_RcParams_class():
-    rc = mpl.RcParams({'font.cursive': ['Apple Chancery',
-                                        'Textile',
-                                        'Zapf Chancery',
-                                        'cursive'],
+    rc = mpl.RcParams({'font.cursive': ['Zapf Chancery', 'cursive'],
                        'font.family': 'sans-serif',
                        'font.weight': 'normal',
                        'font.size': 12})
 
     expected_repr = """
-RcParams({'font.cursive': ['Apple Chancery',
-                           'Textile',
-                           'Zapf Chancery',
-                           'cursive'],
+RcParams({
+          'font.cursive': ['Zapf Chancery', 'cursive'],
           'font.family': ['sans-serif'],
           'font.size': 12.0,
-          'font.weight': 'normal'})""".lstrip()
+          'font.weight': 'normal',
+         })""".lstrip()
 
-    assert expected_repr == repr(rc)
+    actual_repr = repr(rc)
+    if sys.version_info[:2] < (3, 15):
+        actual_repr = (actual_repr
+                       .replace("{'", "{\n          '")
+                       .replace("'}", "',\n         }"))
+
+    assert actual_repr == expected_repr
 
     expected_str = """
-font.cursive: ['Apple Chancery', 'Textile', 'Zapf Chancery', 'cursive']
+font.cursive: ['Zapf Chancery', 'cursive']
 font.family: ['sans-serif']
 font.size: 12.0
 font.weight: normal""".lstrip()
 
-    assert expected_str == str(rc)
+    assert str(rc) == expected_str
 
     # test the find_all functionality
     assert ['font.cursive', 'font.size'] == sorted(rc.find_all('i[vz]'))