gh-109485: Further improve test_future_stmt tests

Lib/test/test_future_stmt/test_future.py

@@ -10,6 +10,8 @@
 import re
 import sys
 
+TOP_LEVEL_MSG = 'from __future__ imports must occur at the beginning of the file'
+
 rx = re.compile(r'\((\S+).py, line (\d+)')
 
 def get_error_location(msg):
@@ -18,21 +20,48 @@ def get_error_location(msg):
 
 class FutureTest(unittest.TestCase):
 
- def check_syntax_error(self, err, basename, lineno, offset=1):
- self.assertIn('%s.py, line %d' % (basename, lineno), str(err))
- self.assertEqual(os.path.basename(err.filename), basename + '.py')
+ def check_syntax_error(self, err, basename,
+ *,
+ lineno,
+ message=TOP_LEVEL_MSG, offset=1):
+ if basename != '<string>':
+ basename += '.py'
+
+ self.assertEqual(f'{message} ({basename}, line {lineno})', str(err))
+ self.assertEqual(os.path.basename(err.filename), basename)
  self.assertEqual(err.lineno, lineno)
  self.assertEqual(err.offset, offset)
 
- def test_future1(self):
- with import_helper.CleanImport('test.test_future_stmt.future_test1'):
- from test.test_future_stmt import future_test1
- self.assertEqual(future_test1.result, 6)
+ def assertSyntaxError(self, code,
+ *,
+ lineno=1,
+ message=TOP_LEVEL_MSG, offset=1,
+ parametrize_docstring=True):
+ code = dedent(code.lstrip('\n'))
+ for add_docstring in ([False, True] if parametrize_docstring else [False]):
+ with self.subTest(code=code, add_docstring=add_docstring):
+ if add_docstring:
+ code = '"""Docstring"""\n' + code
+ lineno += 1
+ with self.assertRaises(SyntaxError) as cm:
+ exec(code)
+ self.check_syntax_error(cm.exception, "<string>",
+ lineno=lineno,
+ message=message,
+ offset=offset)
+
+ def test_import_nested_scope_twice(self):
+ # Import the name nested_scopes twice to trigger SF bug #407394
+ with import_helper.CleanImport(
+ 'test.test_future_stmt.import_nested_scope_twice',
+ ):
+ from test.test_future_stmt import import_nested_scope_twice
+ self.assertEqual(import_nested_scope_twice.result, 6)
 
- def test_future2(self):
- with import_helper.CleanImport('test.test_future_stmt.future_test2'):
- from test.test_future_stmt import future_test2
-self.assertEqual(future_test2.result, 6)
+ def test_nested_scope(self):
+ with import_helper.CleanImport('test.test_future_stmt.nested_scope'):
+ from test.test_future_stmt import nested_scope
+ self.assertEqual(nested_scope.result, 6)
 
  def test_future_single_import(self):
  with import_helper.CleanImport(
@@ -52,45 +81,80 @@ def test_future_multiple_features(self):
  ):
  from test.test_future_stmt import test_future_multiple_features
 
- def test_badfuture3(self):
- with self.assertRaises(SyntaxError) as cm:
- from test.test_future_stmt import badsyntax_future3
- self.check_syntax_error(cm.exception, "badsyntax_future3", 3)
+ def test_unknown_future_flag(self):
+ code = """
+ from __future__ import nested_scopes
+ from __future__ import rested_snopes # typo error here: nested => rested
+ """
+ self.assertSyntaxError(
+ code, lineno=2,
+ message='future feature rested_snopes is not defined',
+ )
 
- def test_badfuture4(self):
- with self.assertRaises(SyntaxError) as cm:
- from test.test_future_stmt import badsyntax_future4
- self.check_syntax_error(cm.exception, "badsyntax_future4", 3)
+ def test_future_import_not_on_top(self):
+ code = """
+ import some_module
+ from __future__ import annotations
+ """
+ self.assertSyntaxError(code, lineno=2)
 
- def test_badfuture5(self):
- with self.assertRaises(SyntaxError) as cm:
- from test.test_future_stmt import badsyntax_future5
- self.check_syntax_error(cm.exception, "badsyntax_future5", 4)
+ code = """
+ import __future__
+ from __future__ import annotations
+ """
+ self.assertSyntaxError(code, lineno=2)
 
- def test_badfuture6(self):
- with self.assertRaises(SyntaxError) as cm:
- from test.test_future_stmt import badsyntax_future6
- self.check_syntax_error(cm.exception, "badsyntax_future6", 3)
+ code = """
+ from __future__ import absolute_import
+ "spam, bar, blah"
+ from __future__ import print_function
+ """
+ self.assertSyntaxError(code, lineno=3)
 
- def test_badfuture7(self):
- with self.assertRaises(SyntaxError) as cm:
- from test.test_future_stmt import badsyntax_future7
- self.check_syntax_error(cm.exception, "badsyntax_future7", 3, 54)
+ def test_future_import_with_extra_string(self):
+ code = """
+ '''Docstring'''
+ "this isn't a doc string"
+ from __future__ import nested_scopes
+ """
+ self.assertSyntaxError(code, lineno=3, parametrize_docstring=False)
 
- def test_badfuture8(self):
- with self.assertRaises(SyntaxError) as cm:
- from test.test_future_stmt import badsyntax_future8
- self.check_syntax_error(cm.exception, "badsyntax_future8", 3)
+ def test_multiple_import_statements_on_same_line(self):
+ # With `\`:
+ code = """
+ from __future__ import nested_scopes; import string; from __future__ import \
+ nested_scopes
+ """
+ self.assertSyntaxError(code, offset=54)
 
- def test_badfuture9(self):
- with self.assertRaises(SyntaxError) as cm:
- from test.test_future_stmt import badsyntax_future9
- self.check_syntax_error(cm.exception, "badsyntax_future9", 3)
+ # Without `\`:
+ code = """
+ from __future__ import nested_scopes; import string; from __future__ import nested_scopes
+ """
+ self.assertSyntaxError(code, offset=54)
+
+ def test_future_import_star(self):
+ code = """
+ from __future__ import *
+ """
+ self.assertSyntaxError(code, message='future feature * is not defined')
+
+ def test_future_import_braces(self):
+ code = """
+ from __future__ import braces
+ """
+ # Congrats, you found an easter egg!
+ self.assertSyntaxError(code, message='not a chance')
+
+ code = """
+ from __future__ import nested_scopes, braces
+ """
+ self.assertSyntaxError(code, message='not a chance')
 
- def test_badfuture10(self):
+ def test_module_with_future_import_not_on_top(self):
  with self.assertRaises(SyntaxError) as cm:
- from test.test_future_stmt import badsyntax_future10
- self.check_syntax_error(cm.exception, "badsyntax_future10", 3)
+ from test.test_future_stmt import badsyntax_future
+ self.check_syntax_error(cm.exception, "badsyntax_future", lineno=3)
 
  def test_ensure_flags_dont_clash(self):
  # bpo-39562: test that future flags and compiler flags doesn't clash