From 5a26bb9511bcfa8c2fc375fda7233aa0f33dbf81 Mon Sep 17 00:00:00 2001
From: "Nathan G. Wiseman" <55075327+NGWi@users.noreply.github.com>
Date: Tue, 12 Nov 2024 17:49:06 -0500
Subject: [PATCH 01/19] Raise warning if both c and facecolors are used in
 scatter plot. In the future we may implement c as edgecolors in that case or
 cause plot to fail.

---
 lib/matplotlib/axes/_axes.py | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
index f6a4ebfdc7c6..5af7b1997465 100644
--- a/lib/matplotlib/axes/_axes.py
+++ b/lib/matplotlib/axes/_axes.py
@@ -4613,10 +4613,20 @@ def _parse_scatter_color_args(c, edgecolors, kwargs, xsize,
                 edgecolors = kwcolor
             if facecolors is None:
                 facecolors = kwcolor
-
+         
+ 
         if edgecolors is None and not mpl.rcParams['_internal.classic_mode']:
             edgecolors = mpl.rcParams['scatter.edgecolors']
 
+        # Raise a warning if both `c` and `facecolor` are set (issue #24404).
+        if c is not None and facecolors is not None:
+            _api.warn_external(
+                "You passed both c and facecolor/facecolors for the markers. "
+                "Matplotlib is ignoring the facecolor "
+                "in favor of what you specified in c. "
+                "This behavior may change in the future."
+            )
+
         c_was_none = c is None
         if c is None:
             c = (facecolors if facecolors is not None

From f1966c2eb416f553d86d30cc5ac6d8598c2ac77b Mon Sep 17 00:00:00 2001
From: "Nathan G. Wiseman" <55075327+NGWi@users.noreply.github.com>
Date: Tue, 12 Nov 2024 18:26:16 -0500
Subject: [PATCH 02/19] Corrected flake8 formatting warnings.

---
 lib/matplotlib/axes/_axes.py | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
index 5af7b1997465..5ac0cba034ee 100644
--- a/lib/matplotlib/axes/_axes.py
+++ b/lib/matplotlib/axes/_axes.py
@@ -4613,8 +4613,7 @@ def _parse_scatter_color_args(c, edgecolors, kwargs, xsize,
                 edgecolors = kwcolor
             if facecolors is None:
                 facecolors = kwcolor
-         
- 
+
         if edgecolors is None and not mpl.rcParams['_internal.classic_mode']:
             edgecolors = mpl.rcParams['scatter.edgecolors']
 

From 53a082516f02b9d564a45d81d85b720d9b7b41b1 Mon Sep 17 00:00:00 2001
From: "Nathan G. Wiseman" <55075327+NGWi@users.noreply.github.com>
Date: Tue, 12 Nov 2024 20:38:42 -0500
Subject: [PATCH 03/19] Removed offending whitespace and extra line.

To pass flake8 formatting check
---
 lib/matplotlib/axes/_axes.py | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
index 5af7b1997465..5ac0cba034ee 100644
--- a/lib/matplotlib/axes/_axes.py
+++ b/lib/matplotlib/axes/_axes.py
@@ -4613,8 +4613,7 @@ def _parse_scatter_color_args(c, edgecolors, kwargs, xsize,
                 edgecolors = kwcolor
             if facecolors is None:
                 facecolors = kwcolor
-         
- 
+
         if edgecolors is None and not mpl.rcParams['_internal.classic_mode']:
             edgecolors = mpl.rcParams['scatter.edgecolors']
 

From 80318093766a8822a983cffc71576f43d9f74312 Mon Sep 17 00:00:00 2001
From: "Nathan G. Wiseman" <55075327+NGWi@users.noreply.github.com>
Date: Wed, 13 Nov 2024 11:11:58 -0500
Subject: [PATCH 04/19] Corrected old test that qualified for the new warning.

---
 lib/matplotlib/tests/test_legend.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/lib/matplotlib/tests/test_legend.py b/lib/matplotlib/tests/test_legend.py
index 61892378bd03..feb5ef0226f4 100644
--- a/lib/matplotlib/tests/test_legend.py
+++ b/lib/matplotlib/tests/test_legend.py
@@ -974,7 +974,6 @@ def test_legend_pathcollection_labelcolor_markfacecolor_cmap():
         np.arange(10),
         np.arange(10),
         label='#1',
-        c=np.arange(10),
         facecolor=facecolors
     )
 

From 8ae213cd15a9791b350fa9b1d9a0b68e90ed6d6d Mon Sep 17 00:00:00 2001
From: "Nathan G. Wiseman" <55075327+NGWi@users.noreply.github.com>
Date: Mon, 18 Nov 2024 11:58:08 -0500
Subject: [PATCH 05/19] Made message more concise, and straightened old test,
 to fulfill @timhoffm's points.

---
 lib/matplotlib/axes/_axes.py        | 3 +--
 lib/matplotlib/tests/test_legend.py | 4 ++--
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
index 5ac0cba034ee..73c351719328 100644
--- a/lib/matplotlib/axes/_axes.py
+++ b/lib/matplotlib/axes/_axes.py
@@ -4621,8 +4621,7 @@ def _parse_scatter_color_args(c, edgecolors, kwargs, xsize,
         if c is not None and facecolors is not None:
             _api.warn_external(
                 "You passed both c and facecolor/facecolors for the markers. "
-                "Matplotlib is ignoring the facecolor "
-                "in favor of what you specified in c. "
+                "c has precedence over facecolor/facecolors. "
                 "This behavior may change in the future."
             )
 
diff --git a/lib/matplotlib/tests/test_legend.py b/lib/matplotlib/tests/test_legend.py
index feb5ef0226f4..c8963422fdd5 100644
--- a/lib/matplotlib/tests/test_legend.py
+++ b/lib/matplotlib/tests/test_legend.py
@@ -969,12 +969,12 @@ def test_legend_pathcollection_labelcolor_markfacecolor_cmap():
     # test the labelcolor for labelcolor='markerfacecolor' on PathCollection
     # with colormaps
     fig, ax = plt.subplots()
-    facecolors = mpl.cm.viridis(np.random.rand(10))
+    colormap = mpl.cm.viridis(np.random.rand(10))
     ax.scatter(
         np.arange(10),
         np.arange(10),
         label='#1',
-        facecolor=facecolors
+        c=colormap
     )
 
     leg = ax.legend(labelcolor='markerfacecolor')

From 49f03f723ebb18a6e498a80abdfc006a97ba840b Mon Sep 17 00:00:00 2001
From: "Nathan G. Wiseman" <55075327+NGWi@users.noreply.github.com>
Date: Mon, 18 Nov 2024 14:04:16 -0500
Subject: [PATCH 06/19] Added test.

---
 lib/matplotlib/tests/test_axes.py | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
index e3a59a1751ab..9aa1c35b14d3 100644
--- a/lib/matplotlib/tests/test_axes.py
+++ b/lib/matplotlib/tests/test_axes.py
@@ -2765,6 +2765,24 @@ def test_scatter_color_warning(self, kwargs):
         plt.scatter([], [], c=[], **kwargs)
         plt.scatter([1, 2], [3, 4], c=[4, 5], **kwargs)
 
+    @pytest.mark.parametrize('colors', 
+        [
+            ('red', 'blue'),                        # simple string colors
+            (['red', 'blue'], ['green', 'yellow']),      # array of colors
+            ([[1, 0, 0], [0, 1, 0]], [[0, 0, 1], [1, 1, 0]])  # RGB values
+        ])
+    def test_scatter_c_facecolor_warning(self, colors):
+        warn_match = (
+            "You passed both c and facecolor/facecolors for the markers. "
+            "c has precedence over facecolor/facecolors. This behavior may "
+            "change in the future."
+        )
+        fig, ax = plt.subplots()
+        x = [0, 1] if len(colors[0]) == 2 else [0]
+        y = x
+        with pytest.warns(UserWarning, match=warn_match):
+            ax.scatter(x, y, c=colors[0], facecolors=colors[1])
+        
     def test_scatter_unfilled(self):
         coll = plt.scatter([0, 1, 2], [1, 3, 2], c=['0.1', '0.3', '0.5'],
                            marker=mmarkers.MarkerStyle('o', fillstyle='none'),

From 8234066c28c254e2bc043e6fb96c4ef5a6f1dc4f Mon Sep 17 00:00:00 2001
From: "Nathan G. Wiseman" <55075327+NGWi@users.noreply.github.com>
Date: Mon, 18 Nov 2024 14:12:44 -0500
Subject: [PATCH 07/19] Corrected flake8 linting objections.

---
 lib/matplotlib/tests/test_axes.py | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
index 9aa1c35b14d3..b6cb81a70e3e 100644
--- a/lib/matplotlib/tests/test_axes.py
+++ b/lib/matplotlib/tests/test_axes.py
@@ -2765,12 +2765,12 @@ def test_scatter_color_warning(self, kwargs):
         plt.scatter([], [], c=[], **kwargs)
         plt.scatter([1, 2], [3, 4], c=[4, 5], **kwargs)
 
-    @pytest.mark.parametrize('colors', 
-        [
-            ('red', 'blue'),                        # simple string colors
-            (['red', 'blue'], ['green', 'yellow']),      # array of colors
-            ([[1, 0, 0], [0, 1, 0]], [[0, 0, 1], [1, 1, 0]])  # RGB values
-        ])
+    @pytest.mark.parametrize('colors',
+                                [
+                                    ('red', 'blue'),
+                                    (['red', 'blue'], ['green', 'yellow']),
+                                    ([[1, 0, 0], [0, 1, 0]], [[0, 0, 1], [1, 1, 0]])
+                                ])
     def test_scatter_c_facecolor_warning(self, colors):
         warn_match = (
             "You passed both c and facecolor/facecolors for the markers. "
@@ -2782,7 +2782,7 @@ def test_scatter_c_facecolor_warning(self, colors):
         y = x
         with pytest.warns(UserWarning, match=warn_match):
             ax.scatter(x, y, c=colors[0], facecolors=colors[1])
-        
+
     def test_scatter_unfilled(self):
         coll = plt.scatter([0, 1, 2], [1, 3, 2], c=['0.1', '0.3', '0.5'],
                            marker=mmarkers.MarkerStyle('o', fillstyle='none'),

From 38c092a8faa029842484264b4b490f24a1a74723 Mon Sep 17 00:00:00 2001
From: "Nathan G. Wiseman" <55075327+NGWi@users.noreply.github.com>
Date: Mon, 18 Nov 2024 16:12:17 -0500
Subject: [PATCH 08/19] Added direct test of _parse method to attempt to make
 Codecov happy.

---
 lib/matplotlib/tests/test_axes.py | 67 ++++++++++++++++++++++---------
 1 file changed, 49 insertions(+), 18 deletions(-)

diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
index b6cb81a70e3e..d9637554ea18 100644
--- a/lib/matplotlib/tests/test_axes.py
+++ b/lib/matplotlib/tests/test_axes.py
@@ -2765,24 +2765,6 @@ def test_scatter_color_warning(self, kwargs):
         plt.scatter([], [], c=[], **kwargs)
         plt.scatter([1, 2], [3, 4], c=[4, 5], **kwargs)
 
-    @pytest.mark.parametrize('colors',
-                                [
-                                    ('red', 'blue'),
-                                    (['red', 'blue'], ['green', 'yellow']),
-                                    ([[1, 0, 0], [0, 1, 0]], [[0, 0, 1], [1, 1, 0]])
-                                ])
-    def test_scatter_c_facecolor_warning(self, colors):
-        warn_match = (
-            "You passed both c and facecolor/facecolors for the markers. "
-            "c has precedence over facecolor/facecolors. This behavior may "
-            "change in the future."
-        )
-        fig, ax = plt.subplots()
-        x = [0, 1] if len(colors[0]) == 2 else [0]
-        y = x
-        with pytest.warns(UserWarning, match=warn_match):
-            ax.scatter(x, y, c=colors[0], facecolors=colors[1])
-
     def test_scatter_unfilled(self):
         coll = plt.scatter([0, 1, 2], [1, 3, 2], c=['0.1', '0.3', '0.5'],
                            marker=mmarkers.MarkerStyle('o', fillstyle='none'),
@@ -3066,6 +3048,55 @@ def get_next_color():
             c, None, kwargs={}, xsize=2, get_next_color_func=get_next_color)
 
 
+# Warning message tested in the next two tests.
+WARN_MSG = (
+    "You passed both c and facecolor/facecolors for the markers. "
+    "c has precedence over facecolor/facecolors. This behavior may "
+    "change in the future."
+)
+# Test cases shared between direct and integration tests
+COLOR_TEST_CASES = [
+    ('red', 'blue'),
+    (['red', 'blue'], ['green', 'yellow']),
+    ([[1, 0, 0], [0, 1, 0]], [[0, 0, 1], [1, 1, 0]])
+]
+
+
+@pytest.mark.parametrize('c, facecolor', COLOR_TEST_CASES)
+def test_parse_c_facecolor_warning_direct(c, facecolor):
+    """Test the internal _parse_scatter_color_args method directly."""
+    def get_next_color():
+        return 'blue'
+
+    # Test with facecolors (plural)
+    with pytest.warns(UserWarning, match=WARN_MSG):
+        mpl.axes.Axes._parse_scatter_color_args(
+            c=c, edgecolors=None, kwargs={'facecolors': facecolor},
+            xsize=2, get_next_color_func=get_next_color)
+
+    # Test with facecolor (singular)
+    with pytest.warns(UserWarning, match=WARN_MSG):
+        mpl.axes.Axes._parse_scatter_color_args(
+            c=c, edgecolors=None, kwargs={'facecolor': facecolor},
+            xsize=2, get_next_color_func=get_next_color)
+
+
+@pytest.mark.parametrize('c, facecolor', COLOR_TEST_CASES)
+def test_scatter_c_facecolor_warning_integration(c, facecolor):
+    """Test the warning through the actual scatter plot creation."""
+    fig, ax = plt.subplots()
+    x = [0, 1] if isinstance(c, (list, tuple)) else [0]
+    y = x
+
+    # Test with facecolors (plural)
+    with pytest.warns(UserWarning, match=WARN_MSG):
+        ax.scatter(x, y, c=c, facecolors=facecolor)
+
+    # Test with facecolor (singular)
+    with pytest.warns(UserWarning, match=WARN_MSG):
+        ax.scatter(x, y, c=c, facecolor=facecolor)
+
+
 def test_as_mpl_axes_api():
     # tests the _as_mpl_axes api
     class Polar:

From e6e49aa3d200da802c23297075cfc20dae2bb510 Mon Sep 17 00:00:00 2001
From: "Nathan G. Wiseman" <55075327+NGWi@users.noreply.github.com>
Date: Tue, 3 Dec 2024 17:10:05 -0500
Subject: [PATCH 09/19] Added pragma tags for code coverage to ignore unused
 but untested simplified return.

---
 lib/matplotlib/tests/test_axes.py | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
index d9637554ea18..ae2192ae2715 100644
--- a/lib/matplotlib/tests/test_axes.py
+++ b/lib/matplotlib/tests/test_axes.py
@@ -2906,7 +2906,7 @@ def test_scatter_different_shapes(self, fig_test, fig_ref):
     @pytest.mark.parametrize('c_case, re_key', params_test_scatter_c)
     def test_scatter_c(self, c_case, re_key):
         def get_next_color():
-            return 'blue'  # currently unused
+            return 'blue'  # currently unused   # pragma: no cover
 
         xsize = 4
         # Additional checking of *c* (introduced in #11383).
@@ -3000,7 +3000,7 @@ def _params(c=None, xsize=2, *, edgecolors=None, **kwargs):
      ])
 def test_parse_scatter_color_args(params, expected_result):
     def get_next_color():
-        return 'blue'  # currently unused
+        return 'blue'  # currently unused   # pragma: no cover
 
     c, colors, _edgecolors = mpl.axes.Axes._parse_scatter_color_args(
         *params, get_next_color_func=get_next_color)
@@ -3027,7 +3027,7 @@ def get_next_color():
      ])
 def test_parse_scatter_color_args_edgecolors(kwargs, expected_edgecolors):
     def get_next_color():
-        return 'blue'  # currently unused
+        return 'blue'  # currently unused   # pragma: no cover
 
     c = kwargs.pop('c', None)
     edgecolors = kwargs.pop('edgecolors', None)
@@ -3039,7 +3039,7 @@ def get_next_color():
 
 def test_parse_scatter_color_args_error():
     def get_next_color():
-        return 'blue'  # currently unused
+        return 'blue'  # currently unused   # pragma: no cover
 
     with pytest.raises(ValueError,
                        match="RGBA values should be within 0-1 range"):
@@ -3066,7 +3066,7 @@ def get_next_color():
 def test_parse_c_facecolor_warning_direct(c, facecolor):
     """Test the internal _parse_scatter_color_args method directly."""
     def get_next_color():
-        return 'blue'
+        return 'blue'  # currently unused   # pragma: no cover
 
     # Test with facecolors (plural)
     with pytest.warns(UserWarning, match=WARN_MSG):

From 39e18997a2d680fb8f2e260f4e5325f166b3a0f5 Mon Sep 17 00:00:00 2001
From: "Nathan G. Wiseman" <55075327+NGWi@users.noreply.github.com>
Date: Tue, 12 Nov 2024 17:49:06 -0500
Subject: [PATCH 10/19] Raise warning if both c and facecolors are used in
 scatter plot. In the future we may implement c as edgecolors in that case or
 cause plot to fail.

---
 lib/matplotlib/axes/_axes.py | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
index 9bfcc446f6a6..23510d4b2d15 100644
--- a/lib/matplotlib/axes/_axes.py
+++ b/lib/matplotlib/axes/_axes.py
@@ -4666,10 +4666,20 @@ def _parse_scatter_color_args(c, edgecolors, kwargs, xsize,
                 edgecolors = kwcolor
             if facecolors is None:
                 facecolors = kwcolor
-
+         
+ 
         if edgecolors is None and not mpl.rcParams['_internal.classic_mode']:
             edgecolors = mpl.rcParams['scatter.edgecolors']
 
+        # Raise a warning if both `c` and `facecolor` are set (issue #24404).
+        if c is not None and facecolors is not None:
+            _api.warn_external(
+                "You passed both c and facecolor/facecolors for the markers. "
+                "Matplotlib is ignoring the facecolor "
+                "in favor of what you specified in c. "
+                "This behavior may change in the future."
+            )
+
         c_was_none = c is None
         if c is None:
             c = (facecolors if facecolors is not None

From 06c8a76eb27942c8f83bc401bc934a9a0eb783e1 Mon Sep 17 00:00:00 2001
From: "Nathan G. Wiseman" <55075327+NGWi@users.noreply.github.com>
Date: Tue, 12 Nov 2024 18:26:16 -0500
Subject: [PATCH 11/19] Corrected flake8 formatting warnings.

---
 lib/matplotlib/axes/_axes.py | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
index 23510d4b2d15..6fc458babb09 100644
--- a/lib/matplotlib/axes/_axes.py
+++ b/lib/matplotlib/axes/_axes.py
@@ -4666,8 +4666,7 @@ def _parse_scatter_color_args(c, edgecolors, kwargs, xsize,
                 edgecolors = kwcolor
             if facecolors is None:
                 facecolors = kwcolor
-         
- 
+
         if edgecolors is None and not mpl.rcParams['_internal.classic_mode']:
             edgecolors = mpl.rcParams['scatter.edgecolors']
 

From 72138c6ce0f45b053e54eea8ff89e2e0983c780a Mon Sep 17 00:00:00 2001
From: "Nathan G. Wiseman" <55075327+NGWi@users.noreply.github.com>
Date: Wed, 13 Nov 2024 11:11:58 -0500
Subject: [PATCH 12/19] Corrected old test that qualified for the new warning.

---
 lib/matplotlib/tests/test_legend.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/lib/matplotlib/tests/test_legend.py b/lib/matplotlib/tests/test_legend.py
index 61892378bd03..feb5ef0226f4 100644
--- a/lib/matplotlib/tests/test_legend.py
+++ b/lib/matplotlib/tests/test_legend.py
@@ -974,7 +974,6 @@ def test_legend_pathcollection_labelcolor_markfacecolor_cmap():
         np.arange(10),
         np.arange(10),
         label='#1',
-        c=np.arange(10),
         facecolor=facecolors
     )
 

From 319b92b002920f4a4440dc2cd06c32d59b470e80 Mon Sep 17 00:00:00 2001
From: "Nathan G. Wiseman" <55075327+NGWi@users.noreply.github.com>
Date: Mon, 18 Nov 2024 11:58:08 -0500
Subject: [PATCH 13/19] Made message more concise, and straightened old test,
 to fulfill @timhoffm's points.

---
 lib/matplotlib/axes/_axes.py        | 3 +--
 lib/matplotlib/tests/test_legend.py | 4 ++--
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
index 6fc458babb09..72af2674c676 100644
--- a/lib/matplotlib/axes/_axes.py
+++ b/lib/matplotlib/axes/_axes.py
@@ -4674,8 +4674,7 @@ def _parse_scatter_color_args(c, edgecolors, kwargs, xsize,
         if c is not None and facecolors is not None:
             _api.warn_external(
                 "You passed both c and facecolor/facecolors for the markers. "
-                "Matplotlib is ignoring the facecolor "
-                "in favor of what you specified in c. "
+                "c has precedence over facecolor/facecolors. "
                 "This behavior may change in the future."
             )
 
diff --git a/lib/matplotlib/tests/test_legend.py b/lib/matplotlib/tests/test_legend.py
index feb5ef0226f4..c8963422fdd5 100644
--- a/lib/matplotlib/tests/test_legend.py
+++ b/lib/matplotlib/tests/test_legend.py
@@ -969,12 +969,12 @@ def test_legend_pathcollection_labelcolor_markfacecolor_cmap():
     # test the labelcolor for labelcolor='markerfacecolor' on PathCollection
     # with colormaps
     fig, ax = plt.subplots()
-    facecolors = mpl.cm.viridis(np.random.rand(10))
+    colormap = mpl.cm.viridis(np.random.rand(10))
     ax.scatter(
         np.arange(10),
         np.arange(10),
         label='#1',
-        facecolor=facecolors
+        c=colormap
     )
 
     leg = ax.legend(labelcolor='markerfacecolor')

From e348dfc52b43040cc704160f17022a667cab05a6 Mon Sep 17 00:00:00 2001
From: "Nathan G. Wiseman" <55075327+NGWi@users.noreply.github.com>
Date: Mon, 18 Nov 2024 14:04:16 -0500
Subject: [PATCH 14/19] Added test.

---
 lib/matplotlib/tests/test_axes.py | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
index a237713cafe7..d2bc0f33ebb8 100644
--- a/lib/matplotlib/tests/test_axes.py
+++ b/lib/matplotlib/tests/test_axes.py
@@ -2779,6 +2779,24 @@ def test_scatter_color_warning(self, kwargs):
         plt.scatter([], [], c=[], **kwargs)
         plt.scatter([1, 2], [3, 4], c=[4, 5], **kwargs)
 
+    @pytest.mark.parametrize('colors', 
+        [
+            ('red', 'blue'),                        # simple string colors
+            (['red', 'blue'], ['green', 'yellow']),      # array of colors
+            ([[1, 0, 0], [0, 1, 0]], [[0, 0, 1], [1, 1, 0]])  # RGB values
+        ])
+    def test_scatter_c_facecolor_warning(self, colors):
+        warn_match = (
+            "You passed both c and facecolor/facecolors for the markers. "
+            "c has precedence over facecolor/facecolors. This behavior may "
+            "change in the future."
+        )
+        fig, ax = plt.subplots()
+        x = [0, 1] if len(colors[0]) == 2 else [0]
+        y = x
+        with pytest.warns(UserWarning, match=warn_match):
+            ax.scatter(x, y, c=colors[0], facecolors=colors[1])
+        
     def test_scatter_unfilled(self):
         coll = plt.scatter([0, 1, 2], [1, 3, 2], c=['0.1', '0.3', '0.5'],
                            marker=mmarkers.MarkerStyle('o', fillstyle='none'),

From fcf6ce2589474fb2be1d35c444e5af1d8d5e8957 Mon Sep 17 00:00:00 2001
From: "Nathan G. Wiseman" <55075327+NGWi@users.noreply.github.com>
Date: Mon, 18 Nov 2024 14:12:44 -0500
Subject: [PATCH 15/19] Corrected flake8 linting objections.

---
 lib/matplotlib/tests/test_axes.py | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
index d2bc0f33ebb8..f4025c103fab 100644
--- a/lib/matplotlib/tests/test_axes.py
+++ b/lib/matplotlib/tests/test_axes.py
@@ -2779,12 +2779,12 @@ def test_scatter_color_warning(self, kwargs):
         plt.scatter([], [], c=[], **kwargs)
         plt.scatter([1, 2], [3, 4], c=[4, 5], **kwargs)
 
-    @pytest.mark.parametrize('colors', 
-        [
-            ('red', 'blue'),                        # simple string colors
-            (['red', 'blue'], ['green', 'yellow']),      # array of colors
-            ([[1, 0, 0], [0, 1, 0]], [[0, 0, 1], [1, 1, 0]])  # RGB values
-        ])
+    @pytest.mark.parametrize('colors',
+                                [
+                                    ('red', 'blue'),
+                                    (['red', 'blue'], ['green', 'yellow']),
+                                    ([[1, 0, 0], [0, 1, 0]], [[0, 0, 1], [1, 1, 0]])
+                                ])
     def test_scatter_c_facecolor_warning(self, colors):
         warn_match = (
             "You passed both c and facecolor/facecolors for the markers. "
@@ -2796,7 +2796,7 @@ def test_scatter_c_facecolor_warning(self, colors):
         y = x
         with pytest.warns(UserWarning, match=warn_match):
             ax.scatter(x, y, c=colors[0], facecolors=colors[1])
-        
+
     def test_scatter_unfilled(self):
         coll = plt.scatter([0, 1, 2], [1, 3, 2], c=['0.1', '0.3', '0.5'],
                            marker=mmarkers.MarkerStyle('o', fillstyle='none'),

From 96019754b07f48c3ff3058007bc3a1a7637740ae Mon Sep 17 00:00:00 2001
From: "Nathan G. Wiseman" <55075327+NGWi@users.noreply.github.com>
Date: Mon, 18 Nov 2024 16:12:17 -0500
Subject: [PATCH 16/19] Added direct test of _parse method to attempt to make
 Codecov happy.

---
 lib/matplotlib/tests/test_axes.py | 67 ++++++++++++++++++++++---------
 1 file changed, 49 insertions(+), 18 deletions(-)

diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
index f4025c103fab..296dafd6b00d 100644
--- a/lib/matplotlib/tests/test_axes.py
+++ b/lib/matplotlib/tests/test_axes.py
@@ -2779,24 +2779,6 @@ def test_scatter_color_warning(self, kwargs):
         plt.scatter([], [], c=[], **kwargs)
         plt.scatter([1, 2], [3, 4], c=[4, 5], **kwargs)
 
-    @pytest.mark.parametrize('colors',
-                                [
-                                    ('red', 'blue'),
-                                    (['red', 'blue'], ['green', 'yellow']),
-                                    ([[1, 0, 0], [0, 1, 0]], [[0, 0, 1], [1, 1, 0]])
-                                ])
-    def test_scatter_c_facecolor_warning(self, colors):
-        warn_match = (
-            "You passed both c and facecolor/facecolors for the markers. "
-            "c has precedence over facecolor/facecolors. This behavior may "
-            "change in the future."
-        )
-        fig, ax = plt.subplots()
-        x = [0, 1] if len(colors[0]) == 2 else [0]
-        y = x
-        with pytest.warns(UserWarning, match=warn_match):
-            ax.scatter(x, y, c=colors[0], facecolors=colors[1])
-
     def test_scatter_unfilled(self):
         coll = plt.scatter([0, 1, 2], [1, 3, 2], c=['0.1', '0.3', '0.5'],
                            marker=mmarkers.MarkerStyle('o', fillstyle='none'),
@@ -3080,6 +3062,55 @@ def get_next_color():
             c, None, kwargs={}, xsize=2, get_next_color_func=get_next_color)
 
 
+# Warning message tested in the next two tests.
+WARN_MSG = (
+    "You passed both c and facecolor/facecolors for the markers. "
+    "c has precedence over facecolor/facecolors. This behavior may "
+    "change in the future."
+)
+# Test cases shared between direct and integration tests
+COLOR_TEST_CASES = [
+    ('red', 'blue'),
+    (['red', 'blue'], ['green', 'yellow']),
+    ([[1, 0, 0], [0, 1, 0]], [[0, 0, 1], [1, 1, 0]])
+]
+
+
+@pytest.mark.parametrize('c, facecolor', COLOR_TEST_CASES)
+def test_parse_c_facecolor_warning_direct(c, facecolor):
+    """Test the internal _parse_scatter_color_args method directly."""
+    def get_next_color():
+        return 'blue'
+
+    # Test with facecolors (plural)
+    with pytest.warns(UserWarning, match=WARN_MSG):
+        mpl.axes.Axes._parse_scatter_color_args(
+            c=c, edgecolors=None, kwargs={'facecolors': facecolor},
+            xsize=2, get_next_color_func=get_next_color)
+
+    # Test with facecolor (singular)
+    with pytest.warns(UserWarning, match=WARN_MSG):
+        mpl.axes.Axes._parse_scatter_color_args(
+            c=c, edgecolors=None, kwargs={'facecolor': facecolor},
+            xsize=2, get_next_color_func=get_next_color)
+
+
+@pytest.mark.parametrize('c, facecolor', COLOR_TEST_CASES)
+def test_scatter_c_facecolor_warning_integration(c, facecolor):
+    """Test the warning through the actual scatter plot creation."""
+    fig, ax = plt.subplots()
+    x = [0, 1] if isinstance(c, (list, tuple)) else [0]
+    y = x
+
+    # Test with facecolors (plural)
+    with pytest.warns(UserWarning, match=WARN_MSG):
+        ax.scatter(x, y, c=c, facecolors=facecolor)
+
+    # Test with facecolor (singular)
+    with pytest.warns(UserWarning, match=WARN_MSG):
+        ax.scatter(x, y, c=c, facecolor=facecolor)
+
+
 def test_as_mpl_axes_api():
     # tests the _as_mpl_axes api
     class Polar:

From a18364c78bd6b93b33a99bcf7c5f7dcbf1a18ab4 Mon Sep 17 00:00:00 2001
From: "Nathan G. Wiseman" <55075327+NGWi@users.noreply.github.com>
Date: Tue, 3 Dec 2024 17:10:05 -0500
Subject: [PATCH 17/19] Added pragma tags for code coverage to ignore unused
 but untested simplified return.

---
 lib/matplotlib/tests/test_axes.py | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
index 296dafd6b00d..faebce873ae2 100644
--- a/lib/matplotlib/tests/test_axes.py
+++ b/lib/matplotlib/tests/test_axes.py
@@ -2920,7 +2920,7 @@ def test_scatter_different_shapes(self, fig_test, fig_ref):
     @pytest.mark.parametrize('c_case, re_key', params_test_scatter_c)
     def test_scatter_c(self, c_case, re_key):
         def get_next_color():
-            return 'blue'  # currently unused
+            return 'blue'  # currently unused   # pragma: no cover
 
         xsize = 4
         # Additional checking of *c* (introduced in #11383).
@@ -3014,7 +3014,7 @@ def _params(c=None, xsize=2, *, edgecolors=None, **kwargs):
      ])
 def test_parse_scatter_color_args(params, expected_result):
     def get_next_color():
-        return 'blue'  # currently unused
+        return 'blue'  # currently unused   # pragma: no cover
 
     c, colors, _edgecolors = mpl.axes.Axes._parse_scatter_color_args(
         *params, get_next_color_func=get_next_color)
@@ -3041,7 +3041,7 @@ def get_next_color():
      ])
 def test_parse_scatter_color_args_edgecolors(kwargs, expected_edgecolors):
     def get_next_color():
-        return 'blue'  # currently unused
+        return 'blue'  # currently unused   # pragma: no cover
 
     c = kwargs.pop('c', None)
     edgecolors = kwargs.pop('edgecolors', None)
@@ -3053,7 +3053,7 @@ def get_next_color():
 
 def test_parse_scatter_color_args_error():
     def get_next_color():
-        return 'blue'  # currently unused
+        return 'blue'  # currently unused   # pragma: no cover
 
     with pytest.raises(ValueError,
                        match="RGBA values should be within 0-1 range"):
@@ -3080,7 +3080,7 @@ def get_next_color():
 def test_parse_c_facecolor_warning_direct(c, facecolor):
     """Test the internal _parse_scatter_color_args method directly."""
     def get_next_color():
-        return 'blue'
+        return 'blue'  # currently unused   # pragma: no cover
 
     # Test with facecolors (plural)
     with pytest.warns(UserWarning, match=WARN_MSG):

From 7c01a7b2dc4ff837dffbcb703ad632e7889bc02f Mon Sep 17 00:00:00 2001
From: "Nathan G. Wiseman" <55075327+NGWi@users.noreply.github.com>
Date: Wed, 4 Dec 2024 10:11:02 -0500
Subject: [PATCH 18/19] Tim's suggestion for naming test's list of colors.

Co-authored-by: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com>
---
 lib/matplotlib/tests/test_legend.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/matplotlib/tests/test_legend.py b/lib/matplotlib/tests/test_legend.py
index c8963422fdd5..460a93f4828f 100644
--- a/lib/matplotlib/tests/test_legend.py
+++ b/lib/matplotlib/tests/test_legend.py
@@ -969,7 +969,7 @@ def test_legend_pathcollection_labelcolor_markfacecolor_cmap():
     # test the labelcolor for labelcolor='markerfacecolor' on PathCollection
     # with colormaps
     fig, ax = plt.subplots()
-    colormap = mpl.cm.viridis(np.random.rand(10))
+    colors = mpl.cm.viridis(np.random.rand(10))
     ax.scatter(
         np.arange(10),
         np.arange(10),

From fd3d9db791b14432dc0f6477c706de3e3f93dee9 Mon Sep 17 00:00:00 2001
From: "Nathan G. Wiseman" <55075327+NGWi@users.noreply.github.com>
Date: Wed, 4 Dec 2024 10:24:12 -0500
Subject: [PATCH 19/19] Corrected call to changed variable name.

---
 lib/matplotlib/tests/test_legend.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/matplotlib/tests/test_legend.py b/lib/matplotlib/tests/test_legend.py
index 460a93f4828f..8e12772ef5ab 100644
--- a/lib/matplotlib/tests/test_legend.py
+++ b/lib/matplotlib/tests/test_legend.py
@@ -974,7 +974,7 @@ def test_legend_pathcollection_labelcolor_markfacecolor_cmap():
         np.arange(10),
         np.arange(10),
         label='#1',
-        c=colormap
+        c=colors
     )
 
     leg = ax.legend(labelcolor='markerfacecolor')