Add unit test for align_titles

Author: trananso

lib/matplotlib/tests/baseline_images/test_figure/figure_align_titles_constrained.png

@@ -66,6 +66,32 @@ def test_align_labels():
     fig.align_labels()
 
 
+@image_comparison(['figure_align_titles_tight.png',
+                   'figure_align_titles_constrained.png'],
+                  tol=0 if platform.machine() == 'x86_64' else 0.01,
+                  style='mpl20')
+def test_align_titles():
+    for layout in ['tight', 'constrained']:
+        fig, axs = plt.subplots(1, 2, layout=layout, width_ratios=[2, 1])
+
+        ax = axs[0]
+        ax.plot(np.arange(0, 1e6, 1000))
+        ax.set_title('Title0 left', loc='left')
+        ax.set_title('Title0 center', loc='center')
+        ax.set_title('Title0 right', loc='right')
+
+        ax = axs[1]
+        ax.plot(np.arange(0, 1e4, 100))
+        ax.set_title('Title1')
+        ax.set_xlabel('Xlabel0')
+        ax.xaxis.set_label_position("top")
+        ax.xaxis.tick_top()
+        for tick in ax.get_xticklabels():
+            tick.set_rotation(90)
+
+        fig.align_titles()
+
+
 def test_align_labels_stray_axes():
     fig, axs = plt.subplots(2, 2)
     for nn, ax in enumerate(axs.flat):