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Code Issues Releases Activity

gh-100746: Improve test_named_expressions.py (#116713)

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Nikita Sobolev 2024-03-13 21:12:40 +03:00 committed by GitHub
parent 7f418fb111
commit 25684e7131
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1 changed files with 68 additions and 2 deletions
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Lib/test/test_named_expressions.py
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@ -298,6 +298,72 @@ class NamedExpressionInvalidTest(unittest.TestCase):
with self.assertRaisesRegex(SyntaxError, msg):
exec(f"lambda: {code}", {}) # Function scope
def test_named_expression_invalid_rebinding_dict_comprehension_iteration_variable(self):
cases = [
("Key reuse", 'i', "{(i := 0): 1 for i in range(5)}"),
("Value reuse", 'i', "{1: (i := 0) for i in range(5)}"),
("Both reuse", 'i', "{(i := 0): (i := 0) for i in range(5)}"),
("Nested reuse", 'j', "{{(j := 0): 1 for i in range(5)} for j in range(5)}"),
("Reuse inner loop target", 'j', "{(j := 0): 1 for i in range(5) for j in range(5)}"),
("Unpacking key reuse", 'i', "{(i := 0): 1 for i, j in {(0, 1)}}"),
("Unpacking value reuse", 'i', "{1: (i := 0) for i, j in {(0, 1)}}"),
("Reuse in loop condition", 'i', "{i+1: 1 for i in range(5) if (i := 0)}"),
("Unreachable reuse", 'i', "{(False or (i:=0)): 1 for i in range(5)}"),
("Unreachable nested reuse", 'i',
"{i: j for i in range(5) for j in range(5) if True or (i:=10)}"),
# Regression tests from https://github.com/python/cpython/issues/87447
("Complex expression: a", "a",
"{(a := 1): 1 for a, (*b, c[d+e::f(g)], h.i) in j}"),
("Complex expression: b", "b",
"{(b := 1): 1 for a, (*b, c[d+e::f(g)], h.i) in j}"),
]
for case, target, code in cases:
msg = f"assignment expression cannot rebind comprehension iteration variable '{target}'"
with self.subTest(case=case):
with self.assertRaisesRegex(SyntaxError, msg):
exec(code, {}) # Module scope
with self.assertRaisesRegex(SyntaxError, msg):
exec(code, {}, {}) # Class scope
with self.assertRaisesRegex(SyntaxError, msg):
exec(f"lambda: {code}", {}) # Function scope
def test_named_expression_invalid_rebinding_dict_comprehension_inner_loop(self):
cases = [
("Inner reuse", 'j', "{i: 1 for i in range(5) if (j := 0) for j in range(5)}"),
("Inner unpacking reuse", 'j', "{i: 1 for i in range(5) if (j := 0) for j, k in {(0, 1)}}"),
]
for case, target, code in cases:
msg = f"comprehension inner loop cannot rebind assignment expression target '{target}'"
with self.subTest(case=case):
with self.assertRaisesRegex(SyntaxError, msg):
exec(code, {}) # Module scope
with self.assertRaisesRegex(SyntaxError, msg):
exec(code, {}, {}) # Class scope
with self.assertRaisesRegex(SyntaxError, msg):
exec(f"lambda: {code}", {}) # Function scope
def test_named_expression_invalid_dict_comprehension_iterable_expression(self):
cases = [
("Top level", "{i: 1 for i in (i := range(5))}"),
("Inside tuple", "{i: 1 for i in (2, 3, i := range(5))}"),
("Inside list", "{i: 1 for i in [2, 3, i := range(5)]}"),
("Different name", "{i: 1 for i in (j := range(5))}"),
("Lambda expression", "{i: 1 for i in (lambda:(j := range(5)))()}"),
("Inner loop", "{i: 1 for i in range(5) for j in (i := range(5))}"),
("Nested comprehension", "{i: 1 for i in {j: 2 for j in (k := range(5))}}"),
("Nested comprehension condition", "{i: 1 for i in {j: 2 for j in range(5) if (j := True)}}"),
("Nested comprehension body", "{i: 1 for i in {(j := True) for j in range(5)}}"),
]
msg = "assignment expression cannot be used in a comprehension iterable expression"
for case, code in cases:
with self.subTest(case=case):
with self.assertRaisesRegex(SyntaxError, msg):
exec(code, {}) # Module scope
with self.assertRaisesRegex(SyntaxError, msg):
exec(code, {}, {}) # Class scope
with self.assertRaisesRegex(SyntaxError, msg):
exec(f"lambda: {code}", {}) # Function scope
def test_named_expression_invalid_mangled_class_variables(self):
code = """class Foo:
def bar(self):
@ -361,7 +427,7 @@ class NamedExpressionAssignmentTest(unittest.TestCase):
def test_named_expression_assignment_10(self):
if (match := 10) == 10:
pass
self.assertEqual(match, 10)
else: self.fail("variable was not assigned using named expression")
def test_named_expression_assignment_11(self):
@ -403,7 +469,7 @@ class NamedExpressionAssignmentTest(unittest.TestCase):
def test_named_expression_assignment_15(self):
while a := False:
pass # This will not run
self.fail("While body executed") # This will not run
self.assertEqual(a, False)