Backport PR #31573: CI: Remove warning raising after new matplotlib release (#31576)

Co-authored-by: Kaiqi Dong <kaiqidong1991@gmail.com>

Author: meeseeksmachine

pandas/tests/plotting/test_converter.py

@@ -8,6 +8,7 @@
 import pandas._config.config as cf
 
 from pandas.compat.numpy import np_datetime64_compat
+import pandas.util._test_decorators as td
 
 from pandas import Index, Period, Series, Timestamp, date_range
 import pandas._testing as tm
@@ -59,16 +60,15 @@ def test_register_by_default(self):
         call = [sys.executable, "-c", code]
         assert subprocess.check_call(call) == 0
 
+    @td.skip_if_no("matplotlib", min_version="3.1.3")
     def test_registering_no_warning(self):
         plt = pytest.importorskip("matplotlib.pyplot")
         s = Series(range(12), index=date_range("2017", periods=12))
         _, ax = plt.subplots()
 
         # Set to the "warn" state, in case this isn't the first test run
         register_matplotlib_converters()
-        with tm.assert_produces_warning(DeprecationWarning, check_stacklevel=False):
-            # GH#30588 DeprecationWarning from 2D indexing
-            ax.plot(s.index, s.values)
+        ax.plot(s.index, s.values)
 
     def test_pandas_plots_register(self):
         pytest.importorskip("matplotlib.pyplot")
@@ -91,6 +91,7 @@ def test_matplotlib_formatters(self):
                 assert Timestamp not in units.registry
             assert Timestamp in units.registry
 
+    @td.skip_if_no("matplotlib", min_version="3.1.3")
     def test_option_no_warning(self):
         pytest.importorskip("matplotlib.pyplot")
         ctx = cf.option_context("plotting.matplotlib.register_converters", False)
@@ -100,15 +101,12 @@ def test_option_no_warning(self):
 
         # Test without registering first, no warning
         with ctx:
-            # GH#30588 DeprecationWarning from 2D indexing on Index
-            with tm.assert_produces_warning(DeprecationWarning, check_stacklevel=False):
-                ax.plot(s.index, s.values)
+            ax.plot(s.index, s.values)
 
         # Now test with registering
         register_matplotlib_converters()
         with ctx:
-            with tm.assert_produces_warning(DeprecationWarning, check_stacklevel=False):
-                ax.plot(s.index, s.values)
+            ax.plot(s.index, s.values)
 
     def test_registry_resets(self):
         units = pytest.importorskip("matplotlib.units")