Code review fixes

image/docker/interfaces.py

@@ -30,12 +30,14 @@ class ManifestInterface(object):
 
   @abstractproperty
   def layers(self):
-    """ Returns the layers of this manifest, from base to leaf or None if none. """
+    """ Returns the layers of this manifest, from base to leaf or None if this kind of manifest
+        does not support layers. """
     pass
 
   @abstractproperty
   def leaf_layer_v1_image_id(self):
-    """ Returns the Docker V1 image ID for the leaf (top) layer, if any, or None if none. """
+    """ Returns the Docker V1 image ID for the leaf (top) layer, if any, or None if
+        not applicable. """
     pass
 
   @abstractproperty
@@ -53,14 +55,15 @@ class ManifestInterface(object):
 
   @abstractmethod
   def child_manifests(self, lookup_manifest_fn):
-    """ Returns an iterator of all manifests that live under this manifest, if any or None if none.
-        The lookup_manifest_fn is a function that, when given a blob content SHA, returns the
-        contents of that blob in storage if any or None if none.
+    """ Returns an iterator of all manifests that live under this manifest, if any or None if not
+        applicable. The lookup_manifest_fn is a function that, when given a blob content SHA,
+        returns the contents of that blob in storage if any or None if none.
     """
 
   @abstractmethod
   def get_manifest_labels(self, lookup_config_fn):
-    """ Returns a dictionary of all the labels defined inside this manifest or None if none. """
+    """ Returns a dictionary of all the labels defined inside this manifest or None if this kind
+        of manifest does not support labels. """
     pass
 
   @abstractmethod

image/docker/schema1.py

@@ -317,7 +317,7 @@ class DockerSchema1Manifest(ManifestInterface):
                                            self._architecture)
     for layer in reversed(self.layers):
       builder.add_layer(str(layer.digest), layer.raw_v1_metadata)
- 
+
     return builder.build()
 
   def _generate_layers(self):

image/docker/schema2/test/test_manifest.py

@@ -73,8 +73,6 @@ def test_valid_manifest():
   assert manifest.leaf_layer.compressed_size == 73109
 
   blob_digests = list(manifest.blob_digests)
-  assert len(blob_digests) == len(manifest.layers) + 1
-
   expected = [str(layer.digest) for layer in manifest.layers] + [manifest.config.digest]
   assert blob_digests == expected