matplotlib · QuLogic · Apr 17, 2026 · Feb 13, 2026
diff --git a/doc/api/next_api_changes/behavior/31148-ES.rst b/doc/api/next_api_changes/behavior/31148-ES.rst
@@ -0,0 +1,6 @@
+Default *style* parameter of ``image_comparison``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The *style* parameter of the `.image_comparison` decorator will become 'mpl20' in
+Matplotlib 3.13. Not passing it and relying on the previous default will warn until the
+change occurs.
diff --git a/lib/matplotlib/__init__.py b/lib/matplotlib/__init__.py
@@ -1374,6 +1374,11 @@ def _init_tests():
             ft2font.__freetype_version__,
             "" if ft2font.__freetype_build_type__ == 'local' else "not ")
 
+    # Generate a shortcut for classic testing style.
+    from matplotlib.style import _base_library, library
+    _base_library['_classic_test'] = library['_classic_test'] = RcParams(
+            _base_library['classic'] | _base_library['_classic_test_patch'])
+
 
 def _replacer(data, value):
     """

diff --git a/lib/matplotlib/testing/decorators.py b/lib/matplotlib/testing/decorators.py
@@ -14,7 +14,7 @@
 import matplotlib.style
 import matplotlib.units
 import matplotlib.testing
-from matplotlib import _pylab_helpers, cbook, ft2font, pyplot as plt, ticker
+from matplotlib import _api, _pylab_helpers, cbook, ft2font, pyplot as plt, ticker
 from matplotlib.figure import Figure
 from .compare import comparable_formats, compare_images, make_test_filename
 from .exceptions import ImageComparisonFailure
@@ -263,8 +263,7 @@ def wrapper(*args, extension, request, **kwargs):
 def image_comparison(baseline_images, extensions=None, tol=0,
                      freetype_version=None, remove_text=False,
                      savefig_kwarg=None,
-                     # Default of mpl_test_settings fixture and cleanup too.
-                     style=("classic", "_classic_test_patch")):
+                     style=None):
     """
     Compare images generated by the test with those specified in
     *baseline_images*, which must correspond, else an `.ImageComparisonFailure`
@@ -316,9 +315,13 @@ def image_comparison(baseline_images, extensions=None, tol=0,
         Optional arguments that are passed to the savefig method.
 
     style : str, dict, or list
-        The optional style(s) to apply to the image test. The test itself
-        can also apply additional styles if desired. Defaults to ``["classic",
-        "_classic_test_patch"]``.
+        The style(s) to apply to the image test. The test itself can also apply
+        additional styles if desired.
+
+        .. versionchanged:: 3.11
+            This defaults to ``['classic', '_classic_test_patch']``, but will be
+            changing to ``'mpl20'`` as of Matplotlib 3.13. A warning is raised if not
+            explicitly passed.
     """
 
     if baseline_images is not None:
@@ -342,6 +345,12 @@ def image_comparison(baseline_images, extensions=None, tol=0,
         extensions = ['png', 'pdf', 'svg']
     if savefig_kwarg is None:
         savefig_kwarg = dict()  # default no kwargs to savefig
+    if style is None:
+        _api.warn_external(
+            'The default for the style parameter of image_comparsion() will be '
+            'changing to "mpl20" in Matplotlib 3.13; explicitly pass style to continue '
+            'working as before and suppress this warning.')
+        style = ('classic', '_classic_test_patch')
     if sys.maxsize <= 2**32:
         tol += 0.06
     return _pytest_image_comparison(

diff --git a/lib/matplotlib/testing/decorators.pyi b/lib/matplotlib/testing/decorators.pyi
@@ -17,7 +17,7 @@ def image_comparison(
     freetype_version: tuple[str, str] | str | None = ...,
     remove_text: bool = ...,
     savefig_kwarg: dict[str, Any] | None = ...,
-    style: RcStyleType = ...,
+    style: RcStyleType | None = ...,
 ) -> Callable[[Callable[_P, _R]], Callable[_P, _R]]: ...
 def check_figures_equal(
     *, extensions: Sequence[str] = ..., tol: float = ...

diff --git a/lib/matplotlib/tests/test_agg.py b/lib/matplotlib/tests/test_agg.py
@@ -92,7 +92,7 @@ def test_long_path():
     fig.savefig(buff, format='png')
 
 
-@image_comparison(['agg_filter.png'], remove_text=True)
+@image_comparison(['agg_filter.png'], remove_text=True, style='_classic_test')
 def test_agg_filter():
     def smooth1d(x, window_len):
         # copied from https://scipy-cookbook.readthedocs.io/

diff --git a/lib/matplotlib/tests/test_arrow_patches.py b/lib/matplotlib/tests/test_arrow_patches.py
@@ -11,7 +11,7 @@ def draw_arrow(ax, t, r):
                                 fc="b", ec='k'))
 
 
-@image_comparison(['fancyarrow_test_image.png'],
+@image_comparison(['fancyarrow_test_image.png'], style='_classic_test',
                   tol=0 if platform.machine() == 'x86_64' else 0.012)
 def test_fancyarrow():
     # Added 0 to test division by zero error described in issue 3930
@@ -110,8 +110,8 @@ def __prepare_fancyarrow_dpi_cor_test():
 
 
 @image_comparison(['fancyarrow_dpi_cor_100dpi.png'], remove_text=True,
-                  tol=0 if platform.machine() == 'x86_64' else 0.02,
-                  savefig_kwarg=dict(dpi=100))
+                  savefig_kwarg=dict(dpi=100), style='_classic_test',
+                  tol=0 if platform.machine() == 'x86_64' else 0.02)
 def test_fancyarrow_dpi_cor_100dpi():
     """
     Check the export of a FancyArrowPatch @ 100 DPI. FancyArrowPatch is
@@ -125,8 +125,8 @@ def test_fancyarrow_dpi_cor_100dpi():
 
 
 @image_comparison(['fancyarrow_dpi_cor_200dpi.png'], remove_text=True,
-                  tol=0 if platform.machine() == 'x86_64' else 0.02,
-                  savefig_kwarg=dict(dpi=200))
+                  savefig_kwarg=dict(dpi=200), style='_classic_test',
+                  tol=0 if platform.machine() == 'x86_64' else 0.02)
 def test_fancyarrow_dpi_cor_200dpi():
     """
     As test_fancyarrow_dpi_cor_100dpi, but exports @ 200 DPI. The relative size

diff --git a/lib/matplotlib/tests/test_artist.py b/lib/matplotlib/tests/test_artist.py
@@ -96,7 +96,7 @@ def test_collection_transform_of_none():
     assert isinstance(c.get_offset_transform(), mtransforms.IdentityTransform)
 
 
-@image_comparison(["clip_path_clipping"], remove_text=True)
+@image_comparison(["clip_path_clipping"], remove_text=True, style='_classic_test')
 def test_clipping():
     exterior = mpath.Path.unit_rectangle().deepcopy()
     exterior.vertices *= 4