使用mockito的单元测试java可选

Question

我想测试一个返回可选客户机的方法。

public Optional<String> doSomething(String place) {
    Optional<Client> client = Optional.empty();
    try {
        client = Optional.ofNullable(clientHelper.get(place));
    } catch (Ex ex) {
        log.warn("Exception occured:", ex);
    }
    return client.isPresent() ? Optional.ofNullable(client.get().getPlaceDetails(place)) : Optional.empty();
}

  @Test
public void testClientHelper(){
    ClientHelper clientHelper =  Mockito.mock(ClientHelper.class);
    Optional<Client> client = Optional.empty();
    Mockito.when(Optional.ofNullable(clientHelper.get("IN"))).thenReturn(client);
    assertEquals( doSomething("IN"), Optional.empty())
}

org.mockito.exceptions.misusing.WrongTypeOfReturnValue: 
Optional cannot be returned by get()
get() should return Client

我一直在跟踪这个链接Mockito错误，方法返回可选的

Answer 1

这里的问题是调用when时使用的内容不是mock。您将传递给它一个可选。

如果我理解您在这里试图做什么，那么clientHelper将通过doSomething方法传递给对象，您希望模拟它以进行测试。如果是这样的话，它更典型地看起来是这样的：

interface ClientHelper {
    Client get(String place) throws Ex;
}

class ClassUnderTest {
    private final ClientHelper clientHelper;

    public ClassUnderTest(ClientHelper helper) {
        this.clientHelper = helper;
    }

    public Optional<String> doSomething(String place) {
        try {
            return Optional.ofNullable(clientHelper.get(place).getPlaceDetails(place));
        } catch (Ex ex) {
            log.warn("Exception: " + ex);
            return Optional.empty();
        }
    }
}

@Test
void testFullHelper() {
    Client client = mock(Client.class);
    when(client.getPlaceDetails("IN")).thenReturn("Details");
    ClientHelper helper = mock(ClientHelper.class);
    when(helper.get("IN")).thenReturn(client);
    ClassUnderTest obj = new ClassUnderTest(helper);
    assertEquals("Details", obj.doSomething("IN"));
}