mirror of
https://github.com/python/cpython.git
synced 2025-07-23 03:05:38 +00:00
6ca030765d
- drop TargetScopeError in favour of raising SyntaxError directly
as per the updated PEP 572
- comprehension iteration variables are explicitly local, but
named expression targets in comprehensions are nonlocal or
global. Raise SyntaxError as specified in PEP 572
- named expression targets in the outermost iterable of a
comprehension have an ambiguous target scope. Avoid resolving
that question now by raising SyntaxError. PEP 572
originally required this only for cases where the bound name
conflicts with the iteration variable in the comprehension,
but CPython can't easily restrict the exception to that case
(as it doesn't know the target variable names when visiting
the outermost iterator expression)
(cherry picked from commit 5dbe0f59b7)
474 lines
15 KiB
Python
474 lines
15 KiB
Python
import os
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import unittest
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class NamedExpressionInvalidTest(unittest.TestCase):
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def test_named_expression_invalid_01(self):
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code = """x := 0"""
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with self.assertRaisesRegex(SyntaxError, "invalid syntax"):
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exec(code, {}, {})
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def test_named_expression_invalid_02(self):
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code = """x = y := 0"""
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with self.assertRaisesRegex(SyntaxError, "invalid syntax"):
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exec(code, {}, {})
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def test_named_expression_invalid_03(self):
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code = """y := f(x)"""
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with self.assertRaisesRegex(SyntaxError, "invalid syntax"):
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exec(code, {}, {})
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def test_named_expression_invalid_04(self):
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code = """y0 = y1 := f(x)"""
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with self.assertRaisesRegex(SyntaxError, "invalid syntax"):
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exec(code, {}, {})
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def test_named_expression_invalid_06(self):
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code = """((a, b) := (1, 2))"""
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with self.assertRaisesRegex(SyntaxError, "cannot use named assignment with tuple"):
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exec(code, {}, {})
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def test_named_expression_invalid_07(self):
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code = """def spam(a = b := 42): pass"""
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with self.assertRaisesRegex(SyntaxError, "invalid syntax"):
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exec(code, {}, {})
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def test_named_expression_invalid_08(self):
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code = """def spam(a: b := 42 = 5): pass"""
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with self.assertRaisesRegex(SyntaxError, "invalid syntax"):
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exec(code, {}, {})
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def test_named_expression_invalid_09(self):
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code = """spam(a=b := 'c')"""
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with self.assertRaisesRegex(SyntaxError, "invalid syntax"):
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exec(code, {}, {})
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def test_named_expression_invalid_10(self):
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code = """spam(x = y := f(x))"""
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with self.assertRaisesRegex(SyntaxError, "invalid syntax"):
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exec(code, {}, {})
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def test_named_expression_invalid_11(self):
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code = """spam(a=1, b := 2)"""
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with self.assertRaisesRegex(SyntaxError,
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"positional argument follows keyword argument"):
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exec(code, {}, {})
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def test_named_expression_invalid_12(self):
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code = """spam(a=1, (b := 2))"""
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with self.assertRaisesRegex(SyntaxError,
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"positional argument follows keyword argument"):
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exec(code, {}, {})
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def test_named_expression_invalid_13(self):
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code = """spam(a=1, (b := 2))"""
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with self.assertRaisesRegex(SyntaxError,
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"positional argument follows keyword argument"):
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exec(code, {}, {})
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def test_named_expression_invalid_14(self):
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code = """(x := lambda: y := 1)"""
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with self.assertRaisesRegex(SyntaxError, "invalid syntax"):
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exec(code, {}, {})
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def test_named_expression_invalid_15(self):
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code = """(lambda: x := 1)"""
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with self.assertRaisesRegex(SyntaxError,
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"cannot use named assignment with lambda"):
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exec(code, {}, {})
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def test_named_expression_invalid_16(self):
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code = "[i + 1 for i in i := [1,2]]"
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with self.assertRaisesRegex(SyntaxError, "invalid syntax"):
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exec(code, {}, {})
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def test_named_expression_invalid_17(self):
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code = "[i := 0, j := 1 for i, j in [(1, 2), (3, 4)]]"
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with self.assertRaisesRegex(SyntaxError, "invalid syntax"):
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exec(code, {}, {})
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def test_named_expression_invalid_in_class_body(self):
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code = """class Foo():
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[(42, 1 + ((( j := i )))) for i in range(5)]
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"""
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with self.assertRaisesRegex(SyntaxError,
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"assignment expression within a comprehension cannot be used in a class body"):
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exec(code, {}, {})
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def test_named_expression_invalid_rebinding_comprehension_iteration_variable(self):
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cases = [
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("Local reuse", 'i', "[i := 0 for i in range(5)]"),
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("Nested reuse", 'j', "[[(j := 0) for i in range(5)] for j in range(5)]"),
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("Reuse inner loop target", 'j', "[(j := 0) for i in range(5) for j in range(5)]"),
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("Unpacking reuse", 'i', "[i := 0 for i, j in [(0, 1)]]"),
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("Reuse in loop condition", 'i', "[i+1 for i in range(5) if (i := 0)]"),
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("Unreachable reuse", 'i', "[False or (i:=0) for i in range(5)]"),
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("Unreachable nested reuse", 'i',
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"[(i, j) for i in range(5) for j in range(5) if True or (i:=10)]"),
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]
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for case, target, code in cases:
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msg = f"assignment expression cannot rebind comprehension iteration variable '{target}'"
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with self.subTest(case=case):
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with self.assertRaisesRegex(SyntaxError, msg):
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exec(code, {}, {})
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def test_named_expression_invalid_rebinding_comprehension_inner_loop(self):
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cases = [
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("Inner reuse", 'j', "[i for i in range(5) if (j := 0) for j in range(5)]"),
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("Inner unpacking reuse", 'j', "[i for i in range(5) if (j := 0) for j, k in [(0, 1)]]"),
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]
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for case, target, code in cases:
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msg = f"comprehension inner loop cannot rebind assignment expression target '{target}'"
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with self.subTest(case=case):
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with self.assertRaisesRegex(SyntaxError, msg):
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exec(code, {}) # Module scope
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with self.assertRaisesRegex(SyntaxError, msg):
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exec(code, {}, {}) # Class scope
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with self.assertRaisesRegex(SyntaxError, msg):
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exec(f"lambda: {code}", {}) # Function scope
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def test_named_expression_invalid_comprehension_iterable_expression(self):
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cases = [
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("Top level", "[i for i in (i := range(5))]"),
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("Inside tuple", "[i for i in (2, 3, i := range(5))]"),
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("Inside list", "[i for i in [2, 3, i := range(5)]]"),
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("Different name", "[i for i in (j := range(5))]"),
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("Lambda expression", "[i for i in (lambda:(j := range(5)))()]"),
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("Inner loop", "[i for i in range(5) for j in (i := range(5))]"),
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("Nested comprehension", "[i for i in [j for j in (k := range(5))]]"),
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("Nested comprehension condition", "[i for i in [j for j in range(5) if (j := True)]]"),
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("Nested comprehension body", "[i for i in [(j := True) for j in range(5)]]"),
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]
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msg = "assignment expression cannot be used in a comprehension iterable expression"
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for case, code in cases:
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with self.subTest(case=case):
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with self.assertRaisesRegex(SyntaxError, msg):
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exec(code, {}) # Module scope
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with self.assertRaisesRegex(SyntaxError, msg):
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exec(code, {}, {}) # Class scope
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with self.assertRaisesRegex(SyntaxError, msg):
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exec(f"lambda: {code}", {}) # Function scope
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class NamedExpressionAssignmentTest(unittest.TestCase):
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def test_named_expression_assignment_01(self):
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(a := 10)
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self.assertEqual(a, 10)
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def test_named_expression_assignment_02(self):
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a = 20
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(a := a)
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self.assertEqual(a, 20)
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def test_named_expression_assignment_03(self):
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(total := 1 + 2)
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self.assertEqual(total, 3)
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def test_named_expression_assignment_04(self):
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(info := (1, 2, 3))
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self.assertEqual(info, (1, 2, 3))
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def test_named_expression_assignment_05(self):
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(x := 1, 2)
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self.assertEqual(x, 1)
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def test_named_expression_assignment_06(self):
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(z := (y := (x := 0)))
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self.assertEqual(x, 0)
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self.assertEqual(y, 0)
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self.assertEqual(z, 0)
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def test_named_expression_assignment_07(self):
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(loc := (1, 2))
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self.assertEqual(loc, (1, 2))
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def test_named_expression_assignment_08(self):
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if spam := "eggs":
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self.assertEqual(spam, "eggs")
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else: self.fail("variable was not assigned using named expression")
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def test_named_expression_assignment_09(self):
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if True and (spam := True):
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self.assertTrue(spam)
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else: self.fail("variable was not assigned using named expression")
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def test_named_expression_assignment_10(self):
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if (match := 10) == 10:
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pass
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else: self.fail("variable was not assigned using named expression")
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def test_named_expression_assignment_11(self):
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def spam(a):
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return a
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input_data = [1, 2, 3]
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res = [(x, y, x/y) for x in input_data if (y := spam(x)) > 0]
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self.assertEqual(res, [(1, 1, 1.0), (2, 2, 1.0), (3, 3, 1.0)])
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def test_named_expression_assignment_12(self):
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def spam(a):
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return a
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res = [[y := spam(x), x/y] for x in range(1, 5)]
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self.assertEqual(res, [[1, 1.0], [2, 1.0], [3, 1.0], [4, 1.0]])
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def test_named_expression_assignment_13(self):
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length = len(lines := [1, 2])
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self.assertEqual(length, 2)
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self.assertEqual(lines, [1,2])
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def test_named_expression_assignment_14(self):
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"""
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Where all variables are positive integers, and a is at least as large
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as the n'th root of x, this algorithm returns the floor of the n'th
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root of x (and roughly doubling the number of accurate bits per
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iteration):
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"""
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a = 9
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n = 2
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x = 3
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while a > (d := x // a**(n-1)):
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a = ((n-1)*a + d) // n
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self.assertEqual(a, 1)
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def test_named_expression_assignment_15(self):
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while a := False:
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pass # This will not run
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self.assertEqual(a, False)
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def test_named_expression_assignment_16(self):
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a, b = 1, 2
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fib = {(c := a): (a := b) + (b := a + c) - b for __ in range(6)}
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self.assertEqual(fib, {1: 2, 2: 3, 3: 5, 5: 8, 8: 13, 13: 21})
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class NamedExpressionScopeTest(unittest.TestCase):
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def test_named_expression_scope_01(self):
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code = """def spam():
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(a := 5)
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print(a)"""
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with self.assertRaisesRegex(NameError, "name 'a' is not defined"):
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exec(code, {}, {})
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def test_named_expression_scope_02(self):
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total = 0
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partial_sums = [total := total + v for v in range(5)]
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self.assertEqual(partial_sums, [0, 1, 3, 6, 10])
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self.assertEqual(total, 10)
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def test_named_expression_scope_03(self):
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containsOne = any((lastNum := num) == 1 for num in [1, 2, 3])
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self.assertTrue(containsOne)
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self.assertEqual(lastNum, 1)
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def test_named_expression_scope_04(self):
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def spam(a):
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return a
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res = [[y := spam(x), x/y] for x in range(1, 5)]
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self.assertEqual(y, 4)
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def test_named_expression_scope_05(self):
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def spam(a):
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return a
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input_data = [1, 2, 3]
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res = [(x, y, x/y) for x in input_data if (y := spam(x)) > 0]
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self.assertEqual(res, [(1, 1, 1.0), (2, 2, 1.0), (3, 3, 1.0)])
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self.assertEqual(y, 3)
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def test_named_expression_scope_06(self):
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res = [[spam := i for i in range(3)] for j in range(2)]
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self.assertEqual(res, [[0, 1, 2], [0, 1, 2]])
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self.assertEqual(spam, 2)
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def test_named_expression_scope_07(self):
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len(lines := [1, 2])
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self.assertEqual(lines, [1, 2])
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def test_named_expression_scope_08(self):
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def spam(a):
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return a
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def eggs(b):
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return b * 2
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res = [spam(a := eggs(b := h)) for h in range(2)]
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self.assertEqual(res, [0, 2])
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self.assertEqual(a, 2)
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self.assertEqual(b, 1)
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def test_named_expression_scope_09(self):
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def spam(a):
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return a
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def eggs(b):
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return b * 2
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res = [spam(a := eggs(a := h)) for h in range(2)]
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self.assertEqual(res, [0, 2])
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self.assertEqual(a, 2)
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def test_named_expression_scope_10(self):
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res = [b := [a := 1 for i in range(2)] for j in range(2)]
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self.assertEqual(res, [[1, 1], [1, 1]])
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self.assertEqual(a, 1)
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self.assertEqual(b, [1, 1])
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def test_named_expression_scope_11(self):
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res = [j := i for i in range(5)]
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self.assertEqual(res, [0, 1, 2, 3, 4])
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self.assertEqual(j, 4)
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def test_named_expression_scope_17(self):
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b = 0
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res = [b := i + b for i in range(5)]
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self.assertEqual(res, [0, 1, 3, 6, 10])
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self.assertEqual(b, 10)
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def test_named_expression_scope_18(self):
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def spam(a):
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return a
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res = spam(b := 2)
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self.assertEqual(res, 2)
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self.assertEqual(b, 2)
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def test_named_expression_scope_19(self):
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def spam(a):
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return a
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res = spam((b := 2))
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self.assertEqual(res, 2)
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self.assertEqual(b, 2)
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def test_named_expression_scope_20(self):
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def spam(a):
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return a
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res = spam(a=(b := 2))
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self.assertEqual(res, 2)
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self.assertEqual(b, 2)
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def test_named_expression_scope_21(self):
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def spam(a, b):
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return a + b
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res = spam(c := 2, b=1)
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self.assertEqual(res, 3)
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self.assertEqual(c, 2)
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def test_named_expression_scope_22(self):
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def spam(a, b):
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return a + b
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res = spam((c := 2), b=1)
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self.assertEqual(res, 3)
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self.assertEqual(c, 2)
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def test_named_expression_scope_23(self):
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def spam(a, b):
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return a + b
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res = spam(b=(c := 2), a=1)
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self.assertEqual(res, 3)
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self.assertEqual(c, 2)
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def test_named_expression_scope_24(self):
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a = 10
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def spam():
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nonlocal a
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(a := 20)
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spam()
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self.assertEqual(a, 20)
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def test_named_expression_scope_25(self):
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ns = {}
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code = """a = 10
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def spam():
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global a
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(a := 20)
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spam()"""
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exec(code, ns, {})
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self.assertEqual(ns["a"], 20)
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def test_named_expression_variable_reuse_in_comprehensions(self):
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# The compiler is expected to raise syntax error for comprehension
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# iteration variables, but should be fine with rebinding of other
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# names (e.g. globals, nonlocals, other assignment expressions)
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# The cases are all defined to produce the same expected result
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# Each comprehension is checked at both function scope and module scope
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rebinding = "[x := i for i in range(3) if (x := i) or not x]"
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filter_ref = "[x := i for i in range(3) if x or not x]"
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body_ref = "[x for i in range(3) if (x := i) or not x]"
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nested_ref = "[j for i in range(3) if x or not x for j in range(3) if (x := i)][:-3]"
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cases = [
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("Rebind global", f"x = 1; result = {rebinding}"),
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("Rebind nonlocal", f"result, x = (lambda x=1: ({rebinding}, x))()"),
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("Filter global", f"x = 1; result = {filter_ref}"),
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("Filter nonlocal", f"result, x = (lambda x=1: ({filter_ref}, x))()"),
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("Body global", f"x = 1; result = {body_ref}"),
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("Body nonlocal", f"result, x = (lambda x=1: ({body_ref}, x))()"),
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("Nested global", f"x = 1; result = {nested_ref}"),
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("Nested nonlocal", f"result, x = (lambda x=1: ({nested_ref}, x))()"),
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]
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for case, code in cases:
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with self.subTest(case=case):
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ns = {}
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exec(code, ns)
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self.assertEqual(ns["x"], 2)
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self.assertEqual(ns["result"], [0, 1, 2])
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if __name__ == "__main__":
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unittest.main()
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