Question

我正在测试一个搜索MongoDB数据库中项目的应用程序。该应用程序可以运行，但是当我运行测试时出现错误。这是测试类：

@Test
public void WhenTrovaImpegnoThenInvokeMongoCollectionFindOne(){
    String data = "01-11-2018";
    doReturn(mongoCollection).when(collection).getMongoCollection();
    doReturn(impegno).when(mongoCollection).find("{data:#}", data).as(Impegno.class);
    collection.trovaImpegno(data);
    verify(mongoCollection, times(1)).findOne("{data:#}", data).as(Impegno.class);
}

我嘲笑了一个MongoCollection对象并监视了受测类：

@Spy
AgendaCollection collection;

@Mock
MongoCollection mongoCollection;

经过测试的方法

public Impegno trovaImpegno(String data){
    Impegno imp = new Impegno();
    imp = getMongoCollection().findOne("{data:#}", data).as(Impegno.class);
    return imp;
}

当我运行应用程序时，在数据库中发现Impegno对象，并且所有对象都能正常工作，但是在测试过程中出现此错误：

WhenTrovaImpegnoThenInvokeMongoCollectionFindOne(agenda.AgendaCollectionTest)  Time elapsed: 0.013 sec  <<< ERROR!
org.mockito.exceptions.misusing.WrongTypeOfReturnValue: 
String cannot be returned by find()
find() should return Find
***
If you're unsure why you're getting above error read on.
Due to the nature of the syntax above problem might occur because:
1. This exception *might* occur in wrongly written multi-threaded tests.
   Please refer to Mockito FAQ on limitations of concurrency testing.
2. A spy is stubbed using when(spy.foo()).then() syntax. It is safer to stub spies - 
   - with doReturn|Throw() family of methods. More in javadocs for Mockito.spy() method.

我没有尝试过：

doReturn(impegno).when(mongoCollection).find();

但是我得到了NullPointerException

Answer 1

我这样解决了这个问题：

@Test
public void WhenTrovaImpegnoThenInvokeMongoCollectionFindOne() throws NullPointerException{
 String data = "01-11-2018";
 FindOne findResult = mock(FindOne.class);
doReturn(mongoCollection).when(collection).getMongoCollection();
doReturn(findResult).when(mongoCollection).findOne("{data:#}", data);
collection.trovaImpegno(data);
verify(mongoCollection).findOne("{data:#}", data);
}

谢谢大家的帮助！

Answer 2

似乎用于存根mongoCollection的find方法的变量'impegno'在应表示Find类型时具有String类型。错误说明非常清楚。

如果我正确理解了这个测试用例，它应该看起来像这样：

@Test
public void WhenTrovaImpegnoThenInvokeMongoCollectionFindOne(){
    String data = "01-11-2018";
    Find findResult = mock(Find.class);
    doReturn(mongoCollection).when(collection).getMongoCollection();
    doReturn(findResult).when(mongoCollection).find(eq("{data:#}"), eq(data));
    doReturn(impegno).when(findResult).as(eq(Impegno.class));
    collection.trovaImpegno(data);
    verify(mongoCollection).findOne(eq("{data:#}"), eq(data));
    verify(findResult).as(eq(Impegno.class));
}

使用Mockito进行测试失败，但是应用程序可以工作

2 个答案: