fix: Ensure a member in tests.base.collector.TDataCollector initialized
fix: Ensure a member in tests.base.collector.TDataCollector initialized

Ensure a member, internal datasets, in instances of
tests.base.collector.TDataCollector initialized when its method
'each_data' is called to a avoid errors when unittest.TestCase.__init__
is called in children classes inherits TDataCollector together with
unittest.TestCase.

ssato/python-anyconfig,ssato/python-anyconfig