Mock appearance/disappearance to force changes in interface , via setting local cache.
        :param tst_name:
        :param tst_type:
        :return:

def mock(self, tst_name, tst_type):
        """
        Mock appearance/disappearance to force changes in interface , via setting local cache.
        :param tst_name:
        :param tst_type:
        :return:
        """
        print(" -> Mock {tst_name} appear".format(**locals()))
        # Service appears
        self.available[tst_name] = tst_type
        yield
        # Service disappear
        self.available.pop(tst_name)
        print(" -> Mock {tst_name} disappear".format(**locals()))