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

2 files changed, 130 insertions, 4 deletions

diff --git a/Lib/lib2to3/tests/test_main.py b/Lib/lib2to3/tests/test_main.py
index 754d5dd..407afa1 100644
--- a/Lib/lib2to3/tests/test_main.py
+++ b/Lib/lib2to3/tests/test_main.py
@@ -1,18 +1,30 @@
 # -*- coding: utf-8 -*-
-import sys
 import codecs
-import logging
 import io
+import logging
+import os
+import shutil
+import sys
+import tempfile
 import unittest
 
 from lib2to3 import main
 
 
+TEST_DATA_DIR = os.path.join(os.path.dirname(__file__), "data")
+PY2_TEST_MODULE = os.path.join(TEST_DATA_DIR, "py2_test_grammar.py")
+
+
 class TestMain(unittest.TestCase):
 
+    def setUp(self):
+        self.temp_dir = None  # tearDown() will rmtree this directory if set.
+
     def tearDown(self):
         # Clean up logging configuration down by main.
         del logging.root.handlers[:]
+        if self.temp_dir:
+            shutil.rmtree(self.temp_dir)
 
     def run_2to3_capture(self, args, in_capture, out_capture, err_capture):
         save_stdin = sys.stdin
@@ -39,3 +51,85 @@ class TestMain(unittest.TestCase):
         self.assertTrue("-print 'nothing'" in output)
         self.assertTrue("WARNING: couldn't encode <stdin>'s diff for "
                         "your terminal" in err.getvalue())
+
+    def setup_test_source_trees(self):
+        """Setup a test source tree and output destination tree."""
+        self.temp_dir = tempfile.mkdtemp()  # tearDown() cleans this up.
+        self.py2_src_dir = os.path.join(self.temp_dir, "python2_project")
+        self.py3_dest_dir = os.path.join(self.temp_dir, "python3_project")
+        os.mkdir(self.py2_src_dir)
+        os.mkdir(self.py3_dest_dir)
+        # Turn it into a package with a few files.
+        self.setup_files = []
+        open(os.path.join(self.py2_src_dir, "__init__.py"), "w").close()
+        self.setup_files.append("__init__.py")
+        shutil.copy(PY2_TEST_MODULE, self.py2_src_dir)
+        self.setup_files.append(os.path.basename(PY2_TEST_MODULE))
+        self.trivial_py2_file = os.path.join(self.py2_src_dir, "trivial.py")
+        self.init_py2_file = os.path.join(self.py2_src_dir, "__init__.py")
+        with open(self.trivial_py2_file, "w") as trivial:
+            trivial.write("print 'I need a simple conversion.'")
+        self.setup_files.append("trivial.py")
+
+    def test_filename_changing_on_output_single_dir(self):
+        """2to3 a single directory with a new output dir and suffix."""
+        self.setup_test_source_trees()
+        out = io.StringIO()
+        err = io.StringIO()
+        suffix = "TEST"
+        ret = self.run_2to3_capture(
+                ["-n", "--add-suffix", suffix, "--write-unchanged-files",
+                 "--no-diffs", "--output-dir",
+                 self.py3_dest_dir, self.py2_src_dir],
+                io.StringIO(""), out, err)
+        self.assertEqual(ret, 0)
+        stderr = err.getvalue()
+        self.assertIn(" implies -w.", stderr)
+        self.assertIn(
+                "Output in %r will mirror the input directory %r layout" % (
+                        self.py3_dest_dir, self.py2_src_dir), stderr)
+        self.assertEqual(set(name+suffix for name in self.setup_files),
+                         set(os.listdir(self.py3_dest_dir)))
+        for name in self.setup_files:
+            self.assertIn("Writing converted %s to %s" % (
+                    os.path.join(self.py2_src_dir, name),
+                    os.path.join(self.py3_dest_dir, name+suffix)), stderr)
+        self.assertRegexpMatches(stderr, r"No changes to .*/__init__\.py")
+        self.assertNotRegex(stderr, r"No changes to .*/trivial\.py")
+
+    def test_filename_changing_on_output_two_files(self):
+        """2to3 two files in one directory with a new output dir."""
+        self.setup_test_source_trees()
+        err = io.StringIO()
+        py2_files = [self.trivial_py2_file, self.init_py2_file]
+        expected_files = set(os.path.basename(name) for name in py2_files)
+        ret = self.run_2to3_capture(
+                ["-n", "-w", "--write-unchanged-files",
+                 "--no-diffs", "--output-dir", self.py3_dest_dir] + py2_files,
+                io.StringIO(""), io.StringIO(), err)
+        self.assertEqual(ret, 0)
+        stderr = err.getvalue()
+        self.assertIn(
+                "Output in %r will mirror the input directory %r layout" % (
+                        self.py3_dest_dir, self.py2_src_dir), stderr)
+        self.assertEqual(expected_files, set(os.listdir(self.py3_dest_dir)))
+
+    def test_filename_changing_on_output_single_file(self):
+        """2to3 a single file with a new output dir."""
+        self.setup_test_source_trees()
+        err = io.StringIO()
+        ret = self.run_2to3_capture(
+                ["-n", "-w", "--no-diffs", "--output-dir", self.py3_dest_dir,
+                 self.trivial_py2_file],
+                io.StringIO(""), io.StringIO(), err)
+        self.assertEqual(ret, 0)
+        stderr = err.getvalue()
+        self.assertIn(
+                "Output in %r will mirror the input directory %r layout" % (
+                        self.py3_dest_dir, self.py2_src_dir), stderr)
+        self.assertEqual(set([os.path.basename(self.trivial_py2_file)]),
+                         set(os.listdir(self.py3_dest_dir)))
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/Lib/lib2to3/tests/test_refactor.py b/Lib/lib2to3/tests/test_refactor.py
index 54edeb4..4b87ed6 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):