135 lines
4.3 KiB
Python
135 lines
4.3 KiB
Python
"""Tests for calc.parser — covers D1 through D5."""
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import unittest
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from .lexer import tokenize
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from .parser import parse, ParseError, Num, BinOp, Unary
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def p(src):
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return parse(tokenize(src))
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class TestPrecedence(unittest.TestCase):
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"""D1 — * and / bind tighter than + and -."""
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def test_add_mul(self):
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# 1+2*3 → BinOp('+', Num(1), BinOp('*', Num(2), Num(3)))
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self.assertEqual(p("1+2*3"), BinOp('+', Num(1), BinOp('*', Num(2), Num(3))))
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def test_mul_add(self):
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# 2*3+1 → BinOp('+', BinOp('*', Num(2), Num(3)), Num(1))
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self.assertEqual(p("2*3+1"), BinOp('+', BinOp('*', Num(2), Num(3)), Num(1)))
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def test_sub_div(self):
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# 10-4/2 → BinOp('-', Num(10), BinOp('/', Num(4), Num(2)))
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self.assertEqual(p("10-4/2"), BinOp('-', Num(10), BinOp('/', Num(4), Num(2))))
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def test_single_number(self):
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self.assertEqual(p("42"), Num(42))
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def test_single_float(self):
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self.assertEqual(p("3.5"), Num(3.5))
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class TestLeftAssociativity(unittest.TestCase):
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"""D2 — same-precedence operators associate left."""
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def test_sub_left(self):
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# 8-3-2 → BinOp('-', BinOp('-', Num(8), Num(3)), Num(2))
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self.assertEqual(p("8-3-2"), BinOp('-', BinOp('-', Num(8), Num(3)), Num(2)))
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def test_div_left(self):
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# 8/4/2 → BinOp('/', BinOp('/', Num(8), Num(4)), Num(2))
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self.assertEqual(p("8/4/2"), BinOp('/', BinOp('/', Num(8), Num(4)), Num(2)))
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def test_add_left(self):
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# 1+2+3 → BinOp('+', BinOp('+', Num(1), Num(2)), Num(3))
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self.assertEqual(p("1+2+3"), BinOp('+', BinOp('+', Num(1), Num(2)), Num(3)))
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def test_mul_left(self):
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# 2*3*4 → BinOp('*', BinOp('*', Num(2), Num(3)), Num(4))
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self.assertEqual(p("2*3*4"), BinOp('*', BinOp('*', Num(2), Num(3)), Num(4)))
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class TestParentheses(unittest.TestCase):
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"""D3 — parentheses override precedence."""
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def test_paren_overrides_mul(self):
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# (1+2)*3 → BinOp('*', BinOp('+', Num(1), Num(2)), Num(3))
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self.assertEqual(p("(1+2)*3"), BinOp('*', BinOp('+', Num(1), Num(2)), Num(3)))
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def test_paren_overrides_div(self):
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# 6/(1+2) → BinOp('/', Num(6), BinOp('+', Num(1), Num(2)))
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self.assertEqual(p("6/(1+2)"), BinOp('/', Num(6), BinOp('+', Num(1), Num(2))))
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def test_nested_parens(self):
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# ((2+3)) → BinOp('+', Num(2), Num(3))
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self.assertEqual(p("((2+3))"), BinOp('+', Num(2), Num(3)))
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def test_paren_single(self):
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self.assertEqual(p("(5)"), Num(5))
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class TestUnaryMinus(unittest.TestCase):
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"""D4 — unary minus."""
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def test_leading(self):
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self.assertEqual(p("-5"), Unary('-', Num(5)))
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def test_paren_group(self):
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# -(1+2) → Unary('-', BinOp('+', Num(1), Num(2)))
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self.assertEqual(p("-(1+2)"), Unary('-', BinOp('+', Num(1), Num(2))))
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def test_after_mul(self):
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# 3 * -2 → BinOp('*', Num(3), Unary('-', Num(2)))
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self.assertEqual(p("3 * -2"), BinOp('*', Num(3), Unary('-', Num(2))))
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def test_double_unary(self):
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# --5 → Unary('-', Unary('-', Num(5)))
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self.assertEqual(p("--5"), Unary('-', Unary('-', Num(5))))
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def test_unary_in_add(self):
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# 1 + -2 → BinOp('+', Num(1), Unary('-', Num(2)))
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self.assertEqual(p("1 + -2"), BinOp('+', Num(1), Unary('-', Num(2))))
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class TestErrors(unittest.TestCase):
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"""D5 — malformed input raises ParseError."""
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def test_trailing_op(self):
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with self.assertRaises(ParseError):
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p("1 +")
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def test_unclosed_paren(self):
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with self.assertRaises(ParseError):
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p("(1")
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def test_two_numbers(self):
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with self.assertRaises(ParseError):
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p("1 2")
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def test_close_then_open(self):
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with self.assertRaises(ParseError):
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p(")(")
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def test_empty(self):
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with self.assertRaises(ParseError):
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p("")
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def test_only_op(self):
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with self.assertRaises(ParseError):
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p("+")
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def test_mismatched_parens(self):
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with self.assertRaises(ParseError):
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p("(1+2")
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def test_parse_error_not_other(self):
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for src in ("1 +", "(1", "1 2", ")(", ""):
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with self.subTest(src=src):
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with self.assertRaises(ParseError):
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p(src)
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if __name__ == '__main__':
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unittest.main()
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