def test_expr_with_addition(self):
lexer = Lexer('3 + 2')
parser = Parser(lexer)
result = parser.expr()
expected = BinOp(left=Num(Token('INTEGER', 3)),
op=Token('ADD', '+'),
right=Num(Token('INTEGER', 2)))
assert result == expected
def test_expr_with_subtraction(self):
lexer = Lexer('3 - 2')
parser = Parser(lexer)
result = parser.expr()
expected = BinOp(left=Num(Token('INTEGER', 3)),
op=Token('SUBTRACT', '-'),
right=Num(Token('INTEGER', 2)))
assert result == expected
