Add test for callable

CharlesHe16 · CharlesHe16 · commit 4fa79f18207f · 2020-12-30T13:51:27.000-08:00
diff --git a/lib/matplotlib/tests/test_sankey.py b/lib/matplotlib/tests/test_sankey.py
@@ -10,3 +10,13 @@ def test_sankey():
 def test_label():
     s = Sankey(flows=[0.25], labels=['First'], orientations=[-1])
     assert s.diagrams[0].texts[0].get_text() == 'First\n0.25'
+
+
+def test_format_using_callable():
+    # test using callable by slightly incrementing above label example
+
+    def show_three_decimal_places(value):
+        return f'{value:.3f}'
+
+    s = Sankey(flows=[0.25], labels=['First'], orientations=[-1], format=show_three_decimal_places)
+    assert s.diagrams[0].texts[0].get_text() == 'First\n0.250'
