Merge pull request matplotlib#29908 from QuLogic/legend-placeholders

TST: Use text placeholders for empty legends

Author: tacaswell

lib/matplotlib/tests/baseline_images/test_axes/stem.png

@@ -4606,14 +4606,12 @@ def test_hist_stacked_weighted():
 
 
 @image_comparison(['stem.png'], style='mpl20', remove_text=True)
-def test_stem():
+def test_stem(text_placeholders):
     x = np.linspace(0.1, 2 * np.pi, 100)
 
     fig, ax = plt.subplots()
-    # Label is a single space to force a legend to be drawn, but to avoid any
-    # text being drawn
     ax.stem(x, np.cos(x),
-            linefmt='C2-.', markerfmt='k+', basefmt='C1-.', label=' ')
+            linefmt='C2-.', markerfmt='k+', basefmt='C1-.', label='stem')
     ax.legend()
 
 

lib/matplotlib/tests/baseline_images/test_backend_pdf/hatching_legend.pdf

@@ -296,14 +296,16 @@ def test_pdfpages_fspath():
         pdf.savefig(plt.figure())
 
 
-@image_comparison(['hatching_legend.pdf'])
-def test_hatching_legend():
+@image_comparison(['hatching_legend.pdf'], style='mpl20')
+def test_hatching_legend(text_placeholders):
     """Test for correct hatching on patches in legend"""
     fig = plt.figure(figsize=(1, 2))
 
     a = Rectangle([0, 0], 0, 0, facecolor="green", hatch="XXXX")
     b = Rectangle([0, 0], 0, 0, facecolor="blue", hatch="XXXX")
 
+    # Verify that hatches in PDFs work after empty labels. See
+    # https://github.com/matplotlib/matplotlib/issues/4469
     fig.legend([a, b, a, b], ["", "", "", ""])
 
 

lib/matplotlib/tests/baseline_images/test_bbox_tight/bbox_inches_tight.pdf

@@ -11,17 +11,18 @@
 from mpl_toolkits.axes_grid1.inset_locator import inset_axes
 
 
-@image_comparison(['bbox_inches_tight'], remove_text=True,
+@image_comparison(['bbox_inches_tight'], remove_text=True, style='mpl20',
                   savefig_kwarg={'bbox_inches': 'tight'})
-def test_bbox_inches_tight():
+def test_bbox_inches_tight(text_placeholders):
     #: Test that a figure saved using bbox_inches='tight' is clipped correctly
     data = [[66386, 174296, 75131, 577908, 32015],
             [58230, 381139, 78045, 99308, 160454],
             [89135, 80552, 152558, 497981, 603535],
             [78415, 81858, 150656, 193263, 69638],
             [139361, 331509, 343164, 781380, 52269]]
 
-    col_labels = row_labels = [''] * 5
+    col_labels = ('Freeze', 'Wind', 'Flood', 'Quake', 'Hail')
+    row_labels = [f'{x} year' for x in (100, 50, 20, 10, 5)]
 
     rows = len(data)
     ind = np.arange(len(col_labels)) + 0.3  # the x locations for the groups
@@ -31,13 +32,13 @@ def test_bbox_inches_tight():
     # the bottom values for stacked bar chart
     fig, ax = plt.subplots(1, 1)
     for row in range(rows):
-        ax.bar(ind, data[row], width, bottom=yoff, align='edge', color='b')
+        ax.bar(ind, data[row], width, bottom=yoff, align='edge')
         yoff = yoff + data[row]
-        cell_text.append([''])
+        cell_text.append([f'{x / 1000:1.1f}' for x in yoff])
     plt.xticks([])
     plt.xlim(0, 5)
-    plt.legend([''] * 5, loc=(1.2, 0.2))
-    fig.legend([''] * 5, bbox_to_anchor=(0, 0.2), loc='lower left')
+    plt.legend(['1', '2', '3', '4', '5'], loc=(1.2, 0.2))
+    fig.legend(['a', 'b', 'c', 'd', 'e'], bbox_to_anchor=(0, 0.2), loc='lower left')
     # Add a table at the bottom of the axes
     cell_text.reverse()
     plt.table(cellText=cell_text, rowLabels=row_labels, colLabels=col_labels,

lib/matplotlib/tests/baseline_images/test_bbox_tight/bbox_inches_tight.png

@@ -332,13 +332,13 @@ def test_marker_as_markerstyle():
 
 
 @image_comparison(['striped_line.png'], remove_text=True, style='mpl20')
-def test_striped_lines():
+def test_striped_lines(text_placeholders):
     rng = np.random.default_rng(19680801)
     _, ax = plt.subplots()
     ax.plot(rng.uniform(size=12), color='orange', gapcolor='blue',
-            linestyle='--', lw=5, label=' ')
+            linestyle='--', lw=5, label='blue in orange')
     ax.plot(rng.uniform(size=12), color='red', gapcolor='black',
-            linestyle=(0, (2, 5, 4, 2)), lw=5, label=' ', alpha=0.5)
+            linestyle=(0, (2, 5, 4, 2)), lw=5, label='black in red', alpha=0.5)
     ax.legend(handlelength=5)
 
 

lib/matplotlib/tests/baseline_images/test_bbox_tight/bbox_inches_tight.svg

@@ -135,9 +135,8 @@ def test_collection():
                        'edgecolor': 'blue'})
 
 
-@image_comparison(['tickedstroke'], remove_text=True, extensions=['png'],
-                  tol=0.22)  # Increased tolerance due to fixed clipping.
-def test_tickedstroke():
+@image_comparison(['tickedstroke.png'], remove_text=True, style='mpl20')
+def test_tickedstroke(text_placeholders):
     fig, (ax1, ax2, ax3) = plt.subplots(1, 3, figsize=(12, 4))
     path = Path.unit_circle()
     patch = patches.PathPatch(path, facecolor='none', lw=2, path_effects=[
@@ -149,13 +148,13 @@ def test_tickedstroke():
     ax1.set_xlim(-2, 2)
     ax1.set_ylim(-2, 2)
 
-    ax2.plot([0, 1], [0, 1], label=' ',
+    ax2.plot([0, 1], [0, 1], label='C0',
              path_effects=[path_effects.withTickedStroke(spacing=7,
                                                          angle=135)])
     nx = 101
     x = np.linspace(0.0, 1.0, nx)
     y = 0.3 * np.sin(x * 8) + 0.4
-    ax2.plot(x, y, label=' ', path_effects=[path_effects.withTickedStroke()])
+    ax2.plot(x, y, label='C1', path_effects=[path_effects.withTickedStroke()])
 
     ax2.legend()