def test_build_tree(self):
r = Rule('hey')
c = ConditionNode([Dummy(True)])
self.assertIs(r._build_tree(c), c)
x = lambda: None
x._evaluate = x
self.assertIs(r._build_tree(x), x)
# Tested None indirectly in the constructor
y = r._build_tree('')
self.assertEqual(y.connector, AND)
self.assertEqual(y.children, [])
self.assertTrue(isinstance(y, ConditionNode))
