Add failing regression test for opaque whiteout handling in flattener

Author: JoshRosen

BUILD.bazel

@@ -120,3 +120,14 @@ sh_test(
         ":pusher.par",
     ],
 )
+
+
+py_test(
+    name = "client_v2_2_unit_tests",
+    size = "large",
+    srcs = [
+        "client_v2_2_unit_tests.py",
+        ":containerregistry",
+    ],
+    main = "client_v2_2_unit_tests.py",
+)

client_v2_2_unit_tests.py

@@ -0,0 +1,118 @@
+# Copyright 2018 Google Inc. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from collections import OrderedDict
+import io
+import tarfile
+import unittest
+
+from containerregistry.client.v2_2 import docker_image as v2_2_image
+
+
+class MockImage(object):
+  def __init__(self):
+    self._fs_layers = OrderedDict()
+
+  def add_layer(self, filenames):
+    buf = io.BytesIO()
+    with tarfile.open(mode='w:', fileobj=buf) as tf:
+      for name in filenames:
+        tarinfo = tarfile.TarInfo(name)
+        if name.endswith("/"):
+          tarinfo.type = tarfile.DIRTYPE
+        tf.addfile(tarinfo)
+    buf.seek(0)
+    new_layer_id = str(len(self._fs_layers))
+    self._fs_layers[new_layer_id] = buf.getvalue()
+
+  def diff_ids(self):
+    return reversed(self._fs_layers.keys())
+
+  def uncompressed_layer(self, layer_id):
+    return self._fs_layers[layer_id]
+
+
+class TestExtract(unittest.TestCase):
+
+  def _test_flatten(self, layer_filenames, expected_output_filenames):
+    img = MockImage()
+    for filenames in layer_filenames:
+      img.add_layer(filenames)
+    buf = io.BytesIO()
+    with tarfile.open(mode='w:', fileobj=buf) as tar:
+      v2_2_image.extract(img, tar)
+    buf.seek(0)
+    output_filenames = []
+    with tarfile.open(mode='r', fileobj=buf) as tar:
+      for tarinfo in tar:
+        if tarinfo.isdir():
+          output_filenames.append(tarinfo.name + "/")
+        else:
+          output_filenames.append(tarinfo.name)
+    self.assertEqual(output_filenames, expected_output_filenames)
+
+  def test_single_layer(self):
+    self._test_flatten(
+      [["/directory/", "/file"]],
+      ["/directory/", "/file"]
+    )
+
+  def test_purely_additive_layers(self):
+    self._test_flatten(
+      [
+        ["dir/", "dir/file1", "file"],
+        ["dir/file2", "file2"]
+      ],
+      ["dir/file2", "file2", "dir/", "dir/file1", "file"]
+    )
+
+  def test_single_file_whiteout(self):
+    self._test_flatten(
+      [
+        ["/foo"],
+        ["/.wh.foo"]
+      ],
+      []
+    )
+
+  def test_parent_directory_whiteout(self):
+    self._test_flatten(
+      [
+        ["/x/a/", "/x/b/", "/x/b/1"],
+        ["/x/.wh.b"]
+      ],
+      ["/x/a/"]
+    )
+
+  def test_opaque_whiteout(self):
+    # Examples from https://github.com/opencontainers/image-spec/blob/master/layer.md#whiteouts
+    self._test_flatten(
+      [
+        ["a/", "a/b/", "a/b/c/", "a/b/c/bar"],
+        ["a/", "a/.wh..wh..opq", "a/b/", "a/b/c/", "a/b/c/foo"],
+      ],
+      ["a/", "a/b/", "a/b/c/", "a/b/c/foo"],
+    )
+
+    self._test_flatten(
+      [
+        ["a/", "a/b/", "a/b/c/", "a/b/c/bar"],
+        ["a/", "a/b/", "a/b/c/", "a/b/c/foo",  "a/.wh..wh..opq"],
+      ],
+      ["a/", "a/b/", "a/b/c/", "a/b/c/foo"],
+    )
+
+
+if __name__ == "__main__":
+  unittest.main(verbosity=2)