common.py: Integrate centralized and reusable testing functionality

- Bugfix for incorrectly managing file-adds in diff. Updated test.

svn/common.py

@@ -450,7 +450,9 @@ def diff(self, old, new, rel_path=None):
         hunks = {}
 
         def _process_hunk(file_hunk_raw):
+            # hunks_info will be `None` for file-adds.
             filepath, hunks_info = self._split_file_hunk(file_hunk_raw)
+
             hunks[filepath] = hunks_info
 
         while True:
@@ -484,6 +486,14 @@ def _split_file_hunk(self, file_hunk):
         # ===================================================================
         filepath = lines[0][len(_FILE_HUNK_PREFIX):]
 
+        # File was added. We have the file-hunk header but no actual hunks.
+        if len(lines) == 3:
+            assert \
+                lines[2] == '', \
+                "Empty diff expects third line to be empty:\n{}".format(lines)
+
+            return filepath, None
+
         assert \
             lines[2].startswith(_HUNK_HEADER_LEFT_PREFIX), \
             "Could not find 'left' header prefix: [{}]".format(lines[2])

svn/utility.py

@@ -1,9 +1,19 @@
+import os
+
+import svn.common
 import svn.local
 import svn.remote
-
+import svn.constants
 
 def get_client(url_or_path, *args, **kwargs):
     if url_or_path[0] == '/':
         return svn.local.LocalClient(url_or_path, *args, **kwargs)
     else:
         return svn.remote.RemoteClient(url_or_path, *args, **kwargs)
+
+def get_common_for_cwd():
+    path = os.getcwd()
+    uri = 'file://{}'.format(path)
+
+    cc = svn.common.CommonClient(uri, svn.constants.LT_URL)
+    return cc