@Test
public void shouldReturnWithProperValueWilma() {

    when(client.sendGetterRequest(OPERATION_MODE_STATUS_URL)).thenReturn(Optional.of(JSON_STRING_WILMA_MODE));
    OperationMode result = operationConfiguration.getOperationMode();
    assertTrue(result == OperationMode.WILMA, "The operation mode should be WILMA.");
    verify(client, never()).sendSetterRequest(anyString());
}