def METHOD_NAME(self, appconfiguration_connection_string, appconfiguration_keyvault_secret_url):
    client = self.create_client(
        appconfiguration_connection_string, keyvault_secret_url=appconfiguration_keyvault_secret_url
    )
    min_backoff = 30000  # 30 Seconds in milliseconds
    # When attempts is < 1 then it acts as if it was 1
    attempts = 0
    client._refresh_timer.attempts = attempts
    backoff = client._refresh_timer._calculate_backoff()
    assert backoff == min_backoff
    attempts = -1
    client._refresh_timer.attempts = attempts
    backoff = client._refresh_timer._calculate_backoff()
    assert backoff == min_backoff