Round dashboards: shape and ring, the ring drawn and turned in every look, Knob preset and face guide in the editor

backend/tests/flow/test_dashboards.py

@@ -445,6 +445,27 @@ def test_a_dashboard_is_cut_into_a_sane_number_of_columns():
             DashboardDef(name="house", columns=columns)
 
 
+def test_a_round_dashboard_is_square_and_rings_one_of_its_own_widgets():
+    dial = WidgetDef(id="dial", type="slider", layout={"lg": Placement(x=1)})
+    stat = WidgetDef(id="stat", type="stat")
+
+    knob = DashboardDef(
+        name="knob",
+        shape="round",
+        canvas_width=360,
+        canvas_height=200,
+        ring="dial",
+        widgets=[dial, stat],
+    )
+
+    assert knob.canvas_height == 360
+    # Drawn along the edge, so the outline of the grid leaves it out.
+    assert [shape.type for shape in knob.footprint] == ["stat"]
+    for shape, ring in (("rect", "dial"), ("round", "gone"), ("round", "stat")):
+        with pytest.raises(ValueError):
+            DashboardDef(name="knob", shape=shape, ring=ring, widgets=[dial, stat])
+
+
 def test_a_setting_refuses_a_message_it_cannot_carry():
     """The same rule a widget binding is held to, from the document alone."""
     DashboardDef(