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bpo-34850: Emit a warning for "is" and "is not" with a literal. (GH-9642)

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Serhiy Storchaka 2019-01-18 07:47:48 +02:00 • committed by GitHub
parent e55cf024ca
commit 3bcbedc9f1
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5 changed files with 95 additions and 11 deletions
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36
Lib/test/test_grammar.py
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@ -1226,11 +1226,33 @@ class GrammarTests(unittest.TestCase):
if 1 > 1: pass
if 1 <= 1: pass
if 1 >= 1: pass
if 1 is 1: pass
if 1 is not 1: pass
if x is x: pass
if x is not x: pass
if 1 in (): pass
if 1 not in (): pass
if 1 < 1 > 1 == 1 >= 1 <= 1 != 1 in 1 not in 1 is 1 is not 1: pass
if 1 < 1 > 1 == 1 >= 1 <= 1 != 1 in 1 not in x is x is not x: pass
def test_comparison_is_literal(self):
def check(test, msg='"is" with a literal'):
with self.assertWarnsRegex(SyntaxWarning, msg):
compile(test, '<testcase>', 'exec')
with warnings.catch_warnings():
warnings.filterwarnings('error', category=SyntaxWarning)
with self.assertRaisesRegex(SyntaxError, msg):
compile(test, '<testcase>', 'exec')
check('x is 1')
check('x is "thing"')
check('1 is x')
check('x is y is 1')
check('x is not 1', '"is not" with a literal')
with warnings.catch_warnings():
warnings.filterwarnings('error', category=SyntaxWarning)
compile('x is None', '<testcase>', 'exec')
compile('x is False', '<testcase>', 'exec')
compile('x is True', '<testcase>', 'exec')
compile('x is ...', '<testcase>', 'exec')
def test_binary_mask_ops(self):
x = 1 & 1
@ -1520,9 +1542,11 @@ class GrammarTests(unittest.TestCase):
self.assertEqual(16 // (4 // 2), 8)
self.assertEqual((16 // 4) // 2, 2)
self.assertEqual(16 // 4 // 2, 2)
self.assertTrue(False is (2 is 3))
self.assertFalse((False is 2) is 3)
self.assertFalse(False is 2 is 3)
x = 2
y = 3
self.assertTrue(False is (x is y))
self.assertFalse((False is x) is y)
self.assertFalse(False is x is y)
def test_matrix_mul(self):
# This is not intended to be a comprehensive test, rather just to be few