bpo-10544: Disallow "yield" in comprehensions and generator expressions. (GH-4564)

2 files changed, 5 insertions, 11 deletions

diff --git a/Lib/test/support/__init__.py b/Lib/test/support/__init__.py
index 22868d4..6c9e31a 100644
--- a/Lib/test/support/__init__.py
+++ b/Lib/test/support/__init__.py
@@ -1061,8 +1061,8 @@ def make_bad_fd():
         file.close()
         unlink(TESTFN)
 
-def check_syntax_error(testcase, statement, *, lineno=None, offset=None):
-    with testcase.assertRaises(SyntaxError) as cm:
+def check_syntax_error(testcase, statement, errtext='', *, lineno=None, offset=None):
+    with testcase.assertRaisesRegex(SyntaxError, errtext) as cm:
         compile(statement, '<test string>', 'exec')
     err = cm.exception
     testcase.assertIsNotNone(err.lineno)
diff --git a/Lib/test/test_grammar.py b/Lib/test/test_grammar.py
index 88c22b8..d89bfdc 100644
--- a/Lib/test/test_grammar.py
+++ b/Lib/test/test_grammar.py
@@ -251,6 +251,8 @@ class CNS:
 
 class GrammarTests(unittest.TestCase):
 
+    check_syntax_error = check_syntax_error
+
     # single_input: NEWLINE | simple_stmt | compound_stmt NEWLINE
     # XXX can't test in a script -- this rule is only used when interactive
 
@@ -920,15 +922,7 @@ class GrammarTests(unittest.TestCase):
         def g(): [x for x in [(yield 1)]]
         def g(): [x for x in [(yield from ())]]
 
-        def check(code, warntext):
-            with self.assertWarnsRegex(DeprecationWarning, warntext):
-                compile(code, '<test string>', 'exec')
-            import warnings
-            with warnings.catch_warnings():
-                warnings.filterwarnings('error', category=DeprecationWarning)
-                with self.assertRaisesRegex(SyntaxError, warntext):
-                    compile(code, '<test string>', 'exec')
-
+        check = self.check_syntax_error
         check("def g(): [(yield x) for x in ()]",
               "'yield' inside list comprehension")
         check("def g(): [x for x in () if not (yield x)]",