Add some basic tests for the changes lib

test/test_changes.py

@@ -0,0 +1,66 @@
+import unittest
+import tarfile
+
+from StringIO import StringIO
+from util.streamlayerformat import AUFS_WHITEOUT
+from util.changes import files_and_dirs_from_tar
+
+class TestChanges(unittest.TestCase):
+  def create_layer(self, **kwargs):
+    output = StringIO()
+    with tarfile.open(fileobj=output, mode='w:gz') as tar:
+      for current_contents in kwargs:
+        current_filename = kwargs[current_contents]
+
+        if current_contents == '_':
+          # This is a deleted file.
+          if current_filename.endswith('/'):
+            current_filename = current_filename[:-1]
+
+          parts = current_filename.split('/')
+          if len(parts) > 1:
+            current_filename = '/'.join(parts[:-1]) + '/' + AUFS_WHITEOUT + parts[-1]
+          else:
+            current_filename = AUFS_WHITEOUT + parts[-1]
+
+          current_contents = ''
+
+        info = tarfile.TarInfo(name=current_filename)
+        info.size = len(current_contents)
+        tar.addfile(info, fileobj=StringIO(current_contents))
+
+    return output.getvalue()
+
+
+  def test_single_layer(self):
+    tar_layer = self.create_layer(
+      foo = 'some_file',
+      bar = 'another_file',
+      meh = 'third_file')
+
+    deleted_prefixes = set()
+    result = list(files_and_dirs_from_tar(StringIO(tar_layer), deleted_prefixes))
+
+    self.assertIn('/some_file', result)
+    self.assertIn('/another_file', result)
+    self.assertIn('/third_file', result)
+
+    self.assertFalse(deleted_prefixes)
+
+
+  def test_delete_file(self):
+    tar_layer = self.create_layer(
+      foo = 'some_file',
+      _ = 'another_file',
+      meh = 'third_file')
+
+    deleted_prefixes = set()
+    result = list(files_and_dirs_from_tar(StringIO(tar_layer), deleted_prefixes))
+
+    self.assertIn('/some_file', result)
+    self.assertIn('/third_file', result)
+
+    self.assertIn('another_file', deleted_prefixes)
+
+if __name__ == '__main__':
+  unittest.main()