126 lines
3.9 KiB
Python
126 lines
3.9 KiB
Python
"""Tests for calc/parser.py — covers D1–D5 from the parse phase plan."""
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import unittest
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from calc.lexer import tokenize
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from calc.parser import parse, ParseError, Num, BinOp, Unary
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def p(src: str):
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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_mul_over_add(self):
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# 1+2*3 => BinOp('+', Num(1), BinOp('*', Num(2), Num(3)))
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tree = p("1+2*3")
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self.assertEqual(tree, BinOp('+', Num(1), BinOp('*', Num(2), Num(3))))
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def test_div_over_sub(self):
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# 10-6/2 => BinOp('-', Num(10), BinOp('/', Num(6), Num(2)))
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tree = p("10-6/2")
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self.assertEqual(tree, BinOp('-', Num(10), BinOp('/', Num(6), Num(2))))
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def test_mul_then_add(self):
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# 2*3+4 => BinOp('+', BinOp('*', Num(2), Num(3)), Num(4))
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tree = p("2*3+4")
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self.assertEqual(tree, BinOp('+', BinOp('*', Num(2), Num(3)), Num(4)))
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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_assoc(self):
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# 8-3-2 => BinOp('-', BinOp('-', Num(8), Num(3)), Num(2))
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tree = p("8-3-2")
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self.assertEqual(tree, BinOp('-', BinOp('-', Num(8), Num(3)), Num(2)))
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def test_div_left_assoc(self):
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# 8/4/2 => BinOp('/', BinOp('/', Num(8), Num(4)), Num(2))
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tree = p("8/4/2")
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self.assertEqual(tree, BinOp('/', BinOp('/', Num(8), Num(4)), Num(2)))
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def test_add_left_assoc(self):
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# 1+2+3 => BinOp('+', BinOp('+', Num(1), Num(2)), Num(3))
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tree = p("1+2+3")
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self.assertEqual(tree, BinOp('+', BinOp('+', Num(1), Num(2)), Num(3)))
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class TestParentheses(unittest.TestCase):
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"""D3 — parens override precedence"""
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def test_paren_forces_add_under_mul(self):
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# (1+2)*3 => BinOp('*', BinOp('+', Num(1), Num(2)), Num(3))
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tree = p("(1+2)*3")
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self.assertEqual(tree, BinOp('*', BinOp('+', Num(1), Num(2)), Num(3)))
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def test_nested_parens(self):
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# ((2+3)) => BinOp('+', Num(2), Num(3))
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tree = p("((2+3))")
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self.assertEqual(tree, BinOp('+', Num(2), Num(3)))
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def test_paren_inside_expr(self):
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# 1*(2+3)*4 => BinOp('*', BinOp('*', Num(1), BinOp('+', Num(2), Num(3))), Num(4))
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tree = p("1*(2+3)*4")
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self.assertEqual(
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tree,
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BinOp('*', BinOp('*', Num(1), BinOp('+', Num(2), Num(3))), Num(4))
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)
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class TestUnaryMinus(unittest.TestCase):
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"""D4 — unary minus"""
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def test_leading_unary(self):
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# -5 => Unary('-', Num(5))
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tree = p("-5")
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self.assertEqual(tree, Unary('-', Num(5)))
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def test_unary_grouped(self):
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# -(1+2) => Unary('-', BinOp('+', Num(1), Num(2)))
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tree = p("-(1+2)")
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self.assertEqual(tree, Unary('-', BinOp('+', Num(1), Num(2))))
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def test_mul_unary(self):
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# 3 * -2 => BinOp('*', Num(3), Unary('-', Num(2)))
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tree = p("3 * -2")
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self.assertEqual(tree, 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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tree = p("--5")
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self.assertEqual(tree, Unary('-', Unary('-', Num(5))))
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class TestErrors(unittest.TestCase):
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"""D5 — malformed input raises ParseError"""
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def test_trailing_operator(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_extra_number(self):
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with self.assertRaises(ParseError):
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p("1 2")
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def test_close_before_open(self):
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with self.assertRaises(ParseError):
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p(")(")
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def test_empty_string(self):
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with self.assertRaises(ParseError):
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p("")
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def test_only_operator(self):
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with self.assertRaises(ParseError):
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p("+")
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if __name__ == "__main__":
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unittest.main()
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