Tests for MemberData.retrieve and _CollectionBase.map finished.

Also fixed Bundle such that it has an empty structured array backend on
init.

Closes #8 and #17.

mdsynthesis/core/aggregators.py

@@ -896,9 +896,9 @@ def dict2multiindex(agg):
 
         # get indexer from *by* keyword
         if by == 'uuid':
-            def get_index(member): member.uuid
+            def get_index(member): return member.uuid
         elif by == 'name':
-            def get_index(member): member.name
+            def get_index(member): return member.name
             names = [member.name for member in self._members]
             if len(set(names)) != len(names):
                 self._members._logger.warning(

mdsynthesis/core/bundle.py

@@ -253,7 +253,13 @@ class _BundleBackend():
     def __init__(self):
         # our table will be a structured array matching the schema of the
         # GroupFile _Members Table
-        self.table = None
+        self.table = np.array(
+                [],
+                dtype={'names': ['uuid', 'containertype', 'abspath'],
+                       'formats': ['a{}'.format(persistence.uuidlength),
+                                   'a{}'.format(persistence.namelength),
+                                   'a{}'.format(persistence.pathlength)]
+                       }).reshape(1, -1)
 
     def _member2record(self, uuid, containertype, basedir):
         """Return a record array from a member's information.
@@ -284,7 +290,7 @@ def add_member(self, uuid, containertype, basedir):
                 basedir of the new member in the filesystem
 
         """
-        if self.table is None:
+        if self.table.shape == (1, 0):
             self.table = self._member2record(uuid, containertype, basedir)
         else:
             # check if uuid already present
@@ -311,7 +317,7 @@ def del_member(self, *uuid, **kwargs):
         purge = kwargs.pop('all', False)
 
         if purge:
-            self.table = None
+            self.__init__()
         else:
             # remove redundant uuids from given list if present
             uuids = set([str(uid) for uid in uuid])