def test_can_lookup_variable_from_the_environment(self):
env = Environment()
env.set("a", 2.0)
env.set("b", 3.0)
parse_tree = [ OperatorFactory.make_operator("*"), Symbol("a"), Symbol("b") ]
result = Evaluator.evaluate(parse_tree, env)
self.assertEqual(result, 6.0)
def test_getting_and_setting_variable(self):
env = Environment()
value = 2.3
env.set("a", value)
self.assertEqual(value, env.get("a"))
