class_docstr: Tests the S3Driver
  
  This was largely ported over from test_lookup_tables.py from the old implementation.
class_docstr_tok: ["Tests","the","S3Driver","This","was","largely","ported","over","from","test_lookup_tables.py","from","the","old","implementation","."]
docstr: LookupTables - DriverCache - set_blank with Time Machine - At ttl
docstr_tok: ["LookupTables","-","DriverCache","-","set_blank","with","Time","Machine","-","At","ttl"]
code: def test_set_blank(self):
      """LookupTables - DriverCache - set_blank with Time Machine - At ttl"""
      self._cache._clock.time_machine(
          datetime(year=2000, month=1, day=1)
      )
  
      assert_false(self._cache.has("key"))
      self._cache.set_blank("key", 1)
      assert_true(self._cache.has("key"))
      assert_equal(self._cache.get("key", "default"), "default")
  
file_path: streamalert/tests/unit/streamalert/shared/lookup_tables/test_cache.py
imports: from datetime import datetime
  from nose.tools import assert_equal, assert_false, assert_true
  from streamalert.shared.lookup_tables.cache import DriverCache
label_desc: Use image node_id 7 for calling the TestDriverCache obj's underlying member method code with example usage: obj.test_set_blank() without return types