Fix truncation of degree-one vertex labels

planarity/express/planarity.pyx

@@ -628,11 +628,12 @@ cdef class PGraph:
             xe = drawplanar_vertex_info['vertex_end']
             x = (xe+xb)/2
             node_labels[node] = (x, y)
-            vertex_bounds[node] = (xb, xe)
             patches += [FancyBboxPatch(
                 (xb, y - 0.25), xe - xb, 0.5,
                 boxstyle="round,pad=0.05",
             )]
+            # Include the padding, which supplies the width for degree-one vertices.
+            vertex_bounds[node] = patches[-1].get_extents().intervalx
 
         p = PatchCollection(
             patches,

tests/test_draw_labels.py

@@ -0,0 +1,46 @@
+"""Exercise label truncation against the rendered vertex rectangles."""
+
+import matplotlib
+
+matplotlib.use('Agg')
+
+import matplotlib.pyplot as plt
+import pytest
+
+import planarity
+
+
+@pytest.fixture(autouse=True)
+def isolated_figures():
+    with matplotlib.rc_context():
+        yield
+    plt.close('all')
+
+
+@pytest.fixture(params=['function', 'method'])
+def draw(request):
+    if request.param == 'function':
+        return planarity.draw
+    return lambda edges, **kwargs: planarity.PGraph(edges).draw(**kwargs)
+
+
+@pytest.mark.parametrize('figsize', [(6.4, 4.8), (8, 6)])
+@pytest.mark.parametrize('edges', [
+    [(0, 1), (1, 2), (2, 3)],
+    [(1, 2)],
+])
+def test_degree_one_labels_fit(draw, edges, figsize):
+    draw(edges, figsize=figsize)
+    expected = {str(node) for edge in edges for node in edge}
+    assert {text.get_text() for text in plt.gca().texts} == expected
+
+
+def test_long_degree_one_label_is_still_truncated(draw):
+    label = 'a_very_long_vertex_label_' * 20
+    draw([(label, 'b'), ('b', 'c'), ('c', 'd')])
+    labels = [text.get_text() for text in plt.gca().texts]
+    assert len(labels) == 4
+    truncated = [text for text in labels if text.endswith('...')]
+    assert len(truncated) == 1
+    assert len(truncated[0]) < len(label)
+    assert set(labels) - set(truncated) == {'b', 'c', 'd'}