def test_chain_draw():
if sys.version_info[0] >= 3:
raise SkipTest("Python 3 support not implemented")
chain = TreeChain('tree', FILE_PATHS)
hist = Hist(100, 0, 1)
chain.draw('a_x', hist=hist)
assert_equal(hist.Integral() > 0, True)
assert_equal(hist.GetEntries(), 300)
# check that Draw can be repeated
hist2 = Hist(100, 0, 1)
chain.draw('a_x', hist=hist2)
assert_equal(hist.Integral(), hist2.Integral())
# draw into a graph
graph = chain.draw("a_x:a_y")
assert_true(isinstance(graph, _GraphBase))
assert_equal(len(graph), chain.GetEntries())
assert_equal(len(graph), 300)
