Issue #13930: Adds ability for 2to3 to write its output to a different

directory tree instead of overwriting the input files.  Adds three command
line options: -o/--output-dir, -W/--write-unchanged-files and --add-suffix.

Feature backports into stable release branches for 2to3 are allowed by
a special exemption:
 http://mail.python.org/pipermail/python-dev/2011-December/115089.html

1 files changed, 34 insertions, 2 deletions

diff --git a/Lib/lib2to3/tests/test_refactor.py b/Lib/lib2to3/tests/test_refactor.py
index 54edeb413e..4b87ed6544 100644
--- a/Lib/lib2to3/tests/test_refactor.py
+++ b/Lib/lib2to3/tests/test_refactor.py
@@ -53,6 +53,12 @@ class TestRefactoringTool(unittest.TestCase):
         self.assertTrue(rt.driver.grammar is
                         pygram.python_grammar_no_print_statement)
 
+    def test_write_unchanged_files_option(self):
+        rt = self.rt()
+        self.assertFalse(rt.write_unchanged_files)
+        rt = self.rt({"write_unchanged_files" : True})
+        self.assertTrue(rt.write_unchanged_files)
+
     def test_fixer_loading_helpers(self):
         contents = ["explicit", "first", "last", "parrot", "preorder"]
         non_prefixed = refactor.get_all_fix_names("myfixes")
@@ -176,7 +182,9 @@ from __future__ import print_function"""
                     "<stdin>", False]
         self.assertEqual(results, expected)
 
-    def check_file_refactoring(self, test_file, fixers=_2TO3_FIXERS):
+    def check_file_refactoring(self, test_file, fixers=_2TO3_FIXERS,
+                               options=None, mock_log_debug=None,
+                               actually_write=True):
         tmpdir = tempfile.mkdtemp(prefix="2to3-test_refactor")
         self.addCleanup(shutil.rmtree, tmpdir)
         # make a copy of the tested file that we can write to
@@ -189,11 +197,15 @@ from __future__ import print_function"""
                 return fp.read()
 
         old_contents = read_file()
-        rt = self.rt(fixers=fixers)
+        rt = self.rt(fixers=fixers, options=options)
+        if mock_log_debug:
+            rt.log_debug = mock_log_debug
 
         rt.refactor_file(test_file)
         self.assertEqual(old_contents, read_file())
 
+        if not actually_write:
+            return
         rt.refactor_file(test_file, True)
         new_contents = read_file()
         self.assertNotEqual(old_contents, new_contents)
@@ -203,6 +215,26 @@ from __future__ import print_function"""
         test_file = os.path.join(FIXER_DIR, "parrot_example.py")
         self.check_file_refactoring(test_file, _DEFAULT_FIXERS)
 
+    def test_refactor_file_write_unchanged_file(self):
+        test_file = os.path.join(FIXER_DIR, "parrot_example.py")
+        debug_messages = []
+        def recording_log_debug(msg, *args):
+            debug_messages.append(msg % args)
+        self.check_file_refactoring(test_file, fixers=(),
+                                    options={"write_unchanged_files": True},
+                                    mock_log_debug=recording_log_debug,
+                                    actually_write=False)
+        # Testing that it logged this message when write=False was passed is
+        # sufficient to see that it did not bail early after "No changes".
+        message_regex = r"Not writing changes to .*%s%s" % (
+                os.sep, os.path.basename(test_file))
+        for message in debug_messages:
+            if "Not writing changes" in message:
+                self.assertRegexpMatches(message, message_regex)
+                break
+        else:
+            self.fail("%r not matched in %r" % (message_regex, debug_messages))
+
     def test_refactor_dir(self):
         def check(structure, expected):
             def mock_refactor_file(self, f, *args):