diff_tree: Add want_unchanged to changes_with_renames.

Change-Id: I6f2abb3f232dc6abe69a26e4db7188d9edf23d6e

NEWS

@@ -78,6 +78,8 @@
   * Optionally create RenameDetectors without passing in tree SHAs.
     (Dave Borowitz)
 
+  * Optionally include unchanged entries in RenameDetectors. (Dave Borowitz)
+
  TEST CHANGES
 
   * If setuptools is installed, "python setup.py test" will now run the testsuite.

dulwich/diff_tree.py

@@ -397,6 +397,7 @@ class RenameDetector(object):
         self._rewrite_threshold = rewrite_threshold
         self._max_files = max_files
         self._find_copies_harder = find_copies_harder
+        self._want_unchanged = False
 
     def _reset(self):
         self._adds = []
@@ -412,8 +413,9 @@ class RenameDetector(object):
         return _similarity_score(old_obj, new_obj) < self._rewrite_threshold
 
     def _collect_changes(self, tree1_id, tree2_id):
+        want_unchanged = self._find_copies_harder or self._want_unchanged
         for change in tree_changes(self._store, tree1_id, tree2_id,
-                                   want_unchanged=self._find_copies_harder):
+                                   want_unchanged=want_unchanged):
             if change.type == CHANGE_ADD:
                 self._adds.append(change)
             elif change.type == CHANGE_DELETE:
@@ -554,11 +556,14 @@ class RenameDetector(object):
         return result
 
     def _prune_unchanged(self):
+        if self._want_unchanged:
+            return
         self._deletes = [d for d in self._deletes if d.type != CHANGE_UNCHANGED]
 
-    def changes_with_renames(self, tree1_id, tree2_id):
+    def changes_with_renames(self, tree1_id, tree2_id, want_unchanged=False):
         """Iterate TreeChanges between two tree SHAs, with rename detection."""
         self._reset()
+        self._want_unchanged = want_unchanged
         self._collect_changes(tree1_id, tree2_id)
         self._find_exact_renames()
         self._find_content_renames()

dulwich/tests/test_diff_tree.py

@@ -490,9 +490,10 @@ class RenameDetectionTest(DiffTestCase):
             self.assertEqual(expected_entries,
                              sorted(perm, key=_tree_change_key))
 
-    def detect_renames(self, tree1, tree2, **kwargs):
+    def detect_renames(self, tree1, tree2, want_unchanged=False, **kwargs):
         detector = RenameDetector(self.store, **kwargs)
-        return detector.changes_with_renames(tree1.id, tree2.id)
+        return detector.changes_with_renames(tree1.id, tree2.id,
+                                             want_unchanged=want_unchanged)
 
     def test_no_renames(self):
         blob1 = make_object(Blob, data='a\nb\nc\nd\n')
@@ -784,3 +785,21 @@ class RenameDetectionTest(DiffTestCase):
                          detector.changes_with_renames(tree1.id, tree2.id))
         self.assertEqual(changes,
                          detector.changes_with_renames(tree1.id, tree2.id))
+
+    def test_want_unchanged(self):
+        blob_a1 = make_object(Blob, data='a\nb\nc\nd\n')
+        blob_b = make_object(Blob, data='b')
+        blob_c2 = make_object(Blob, data='a\nb\nc\ne\n')
+        tree1 = self.commit_tree([('a', blob_a1), ('b', blob_b)])
+        tree2 = self.commit_tree([('c', blob_c2), ('b', blob_b)])
+        detector = RenameDetector(self.store)
+        self.assertEqual(
+          [TreeChange(CHANGE_RENAME, ('a', F, blob_a1.id),
+                      ('c', F, blob_c2.id))],
+          self.detect_renames(tree1, tree2))
+        self.assertEqual(
+          [TreeChange(CHANGE_RENAME, ('a', F, blob_a1.id),
+                      ('c', F, blob_c2.id)),
+           TreeChange(CHANGE_UNCHANGED, ('b', F, blob_b.id),
+                      ('b', F, blob_b.id))],
+          self.detect_renames(tree1, tree2, want_unchanged=True))