def test_pushpop():
table = SymbolTable()
t1 = Symbol("t1", Int(0, 1))
t2_1 = Symbol("t2", Int(0, 2))
t3 = Symbol("t3", Int(0, 3))
t2_2 = Symbol("t2", Int(0, 4))
t4_1 = Symbol("t4", FuncPointer(0, 5))
t4_2 = Symbol("t4", FuncPointer(0, 6))
t5 = Symbol("t5", FuncPointer(0, 7))
table.add(t1)
table.add(t2_1)
assert table == {"t1": t1, "t2": t2_1}
table = table.push()
assert table == {"t1": t1, "t2": t2_1}
table.update({"t3": t3, "t2": t2_2})
assert table == {"t1": t1, "t3": t3, "t2": t2_2}
table = table.push()
assert table == {"t1": t1, "t3": t3, "t2": t2_2}
table.update({"t4": t4_1})
assert table == {"t1": t1, "t3": t3, "t2": t2_2, "t4": t4_1}
table = table.push()
assert table == {"t1": t1, "t3": t3, "t2": t2_2, "t4": t4_1}
table.update({"t4": t4_2, "t5": t5})
assert table == {"t1": t1, "t3": t3, "t2": t2_2, "t4": t4_2, "t5": t5}
table = table.pop()
assert table == {"t1": t1, "t3": t3, "t2": t2_2, "t4": t4_1}
table = table.pop()
assert table == {"t1": t1, "t3": t3, "t2": t2_2}
table = table.pop()
assert table == {"t1": t1, "t2": t2_1}
assert_raises(Exception, table.pop)
