Merge pull request #501 from GavinHuttley/develop

ENH: better support for appended traces to Drawable

src/cogent3/draw/drawable.py

@@ -162,9 +162,9 @@ def bound_to(self, obj):
     def figure(self):
         if not self.traces and hasattr(self, "_build_fig"):
             self._build_fig()
-            traces = self.traces
-        else:
-            traces = [{}]
+
+        traces = self.traces if self.traces else [{}]
+
         xtitle = self.xtitle if not self.xtitle else dict(text=self.xtitle)
         ytitle = self.ytitle if not self.ytitle else dict(text=self.ytitle)
         self.layout.xaxis.title = xtitle

tests/test_draw/test_draw_integration.py

@@ -47,6 +47,24 @@ def _check_drawable_styles(self, method, styles, **kwargs):
             self._check_drawable_attrs(obj.drawable.figure, style)
 
 
+class CustomDrawable(BaseDrawablesTests):
+    """custom applications of Drawable"""
+
+    def test_no_trace(self):
+        """should still produce a valid figure"""
+        d = Drawable()
+        f = d.figure
+        self.assertEqual(f.data, [{}])
+
+    def test_one_trace(self):
+        """should still produce a valid figure"""
+        d = Drawable()
+        trace = dict(type="scatter", x=[0, 1], y=[0, 1])
+        d.add_trace(trace)
+        f = d.figure
+        self.assertEqual(f.data, [trace])
+
+
 class AlignmentDrawablesTests(BaseDrawablesTests):
     """methods on SequenceCollection produce Drawables"""