parser_test.py

import unittest
from tokens import Token, TokenType
from parse import Parser
from nodes import *

class TestParser(unittest.TestCase):
    def test_empty(self):
        tokens = []
        node = Parser(tokens).parse()
        self.assertEqual(node, None)

    def test_numbers(self):
        tokens = [
            Token(TokenType.NUMBER, 27),
            Token(TokenType.PLUS),
            Token(TokenType.NUMBER, 14)
        ]
        node = Parser(tokens).parse()
        self.assertEqual(node, AddNode(NumberNode(27), NumberNode(14)))

        tokens = [
            Token(TokenType.NUMBER, 27),
            Token(TokenType.MINUS),
            Token(TokenType.NUMBER, 14)
        ]

        node = Parser(tokens).parse()
        self.assertEqual(node, SubtractNode(NumberNode(27), NumberNode(14)))

        tokens = [
            Token(TokenType.NUMBER, 27),
            Token(TokenType.MULTIPLY),
            Token(TokenType.NUMBER, 14)
        ]

        node = Parser(tokens).parse()
        self.assertEqual(node, MultiplyNode(NumberNode(27), NumberNode(14)))

        tokens = [
            Token(TokenType.NUMBER, 27),
            Token(TokenType.DIVIDE),
            Token(TokenType.NUMBER, 14)
        ]

        node = Parser(tokens).parse()
        self.assertEqual(node, DivideNode(NumberNode(27), NumberNode(14)))

    def test_full_expression(self):
        tokens = [
            Token(TokenType.NUMBER, 27),
            Token(TokenType.PLUS),
            Token(TokenType.LPAR),
            Token(TokenType.NUMBER, 43),
            Token(TokenType.DIVIDE),
            Token(TokenType.NUMBER, 36),
            Token(TokenType.MINUS),
            Token(TokenType.NUMBER, 48),
            Token(TokenType.RPAR),
            Token(TokenType.MULTIPLY),
            Token(TokenType.NUMBER, 51)
        ] 
        node = Parser(tokens).parse()
        self.assertEqual(node, AddNode(
                NumberNode(27),
                MultiplyNode(
                    SubtractNode(
                        DivideNode(
                            NumberNode(43),
                            NumberNode(36),
                        ),
                        NumberNode(48),
                    ),
                    NumberNode(51),
                )
            )
        )