'Create a stub XBlock backed by in-memory storage.'

def setUp(self):

    self.runtime = mock.MagicMock(Runtime)
    self.field_data = KvsFieldData(kvs=DictKeyValueStore())
    self.scope_ids = ScopeIds('Bob', 'mutablestubxblock', '123', 'import')
    self.xblock = StubXBlockWithMutableFields(self.runtime, self.field_data, self.scope_ids)
    self.fake_children_locations = [BlockUsageLocator(CourseLocator('org', 'course', 'run'), 'mutablestubxblock', 'child1'), BlockUsageLocator(CourseLocator('org', 'course', 'run'), 'mutablestubxblock', 'child2')]
    super(UpdateLocationTest, self).setUp()
