Merge pull request matplotlib#30057 from QuLogic/auto-backport-of-pr-29895-on-v3.10.x

Backport PR matplotlib#29895 on branch v3.10.x (The 'lines.markeredgecolor' now doesn't interfere on the color of errorbar caps)"

Author: dstansby

lib/matplotlib/axes/_axes.py

@@ -3780,7 +3780,7 @@ def _upcast_err(err):
                     'zorder', 'rasterized'):
             if key in kwargs:
                 eb_cap_style[key] = kwargs[key]
-        eb_cap_style['color'] = ecolor
+        eb_cap_style["markeredgecolor"] = ecolor
 
         barcols = []
         caplines = {'x': [], 'y': []}

lib/matplotlib/tests/test_axes.py

@@ -9618,3 +9618,29 @@ def test_axes_set_position_external_bbox_unchanged(fig_test, fig_ref):
     ax_test.set_position([0.25, 0.25, 0.5, 0.5])
     assert (bbox.x0, bbox.y0, bbox.width, bbox.height) == (0.0, 0.0, 1.0, 1.0)
     ax_ref = fig_ref.add_axes([0.25, 0.25, 0.5, 0.5])
+
+
+def test_caps_color():
+    # Creates a simple plot with error bars and a specified ecolor
+    x = np.linspace(0, 10, 10)
+    mpl.rcParams['lines.markeredgecolor'] = 'green'
+    ecolor = 'red'
+
+    fig, ax = plt.subplots()
+    errorbars = ax.errorbar(x, np.sin(x), yerr=0.1, ecolor=ecolor)
+
+    # Tests if the caps have the specified color
+    for cap in errorbars[2]:
+        assert mcolors.same_color(cap.get_edgecolor(), ecolor)
+
+
+def test_caps_no_ecolor():
+    # Creates a simple plot with error bars without specifying ecolor
+    x = np.linspace(0, 10, 10)
+    mpl.rcParams['lines.markeredgecolor'] = 'green'
+    fig, ax = plt.subplots()
+    errorbars = ax.errorbar(x, np.sin(x), yerr=0.1)
+
+    # Tests if the caps have the default color (blue)
+    for cap in errorbars[2]:
+        assert mcolors.same_color(cap.get_edgecolor(), "blue")