Update tests

Author: wf-r

packages/python/plotly/plotly/tests/test_core/test_update_objects/test_update_traces.py

@@ -430,6 +430,10 @@ def select_traces_fixture():
 
 def test_select_traces_integer(select_traces_fixture):
     fig = select_traces_fixture
+    # check that selecting first trace does indeed only select the first
+    tr = list(fig.select_traces(selector=0))
+    assert len(tr) == 1
+    assert tr[0].y[1] == 0
     # check we can index last trace selected
     tr = list(fig.select_traces(selector=-1))[0]
     assert tr.y[1] == 20