使用Mockito模拟异常

文章目录

使用Mockito模拟异常，以MyDictionary类为例进行介绍

class MyDictionary {

    private Map<String, String> wordMap;MyDictionary(){
        wordMap = new HashMap<>();}

    public voidadd(final String word, final String meaning){
        wordMap.put(word, meaning);}

    String getMeaning(final String word){return wordMap.get(word);}}

1 Mock对象模拟异常

1.1方法返回类型非void

如果方法的返回类型非void,那么可以使用when().thenThrow()来模拟异常：

    @Test(expected = NullPointerException.class)
    public voidwhenConfigNonVoidRetunMethodToThrowEx_thenExIsThrown(){
        MyDictionary dictMock =mock(MyDictionary.class);when(dictMock.getMeaning(anyString())).thenThrow(NullPointerException.class);

        dictMock.getMeaning("word");}

1.2方法返回类型是void

如果方法返回类型是void，则使用doThrow来模拟异常

@Test(expected = IllegalStateException.class)
public voidwhenConfigVoidRetunMethodToThrowEx_thenExIsThrown(){
    MyDictionary dictMock =mock(MyDictionary.class);doThrow(IllegalStateException.class).when(dictMock).add(anyString(),anyString());
 
    dictMock.add("word","meaning");}

1.3模拟异常对象

我们不仅可以在thenThrow()或者doThrow() 中模拟异常类，还可以模拟异常对象。

    @Test(expected = NullPointerException.class)
    public voidwhenConfigNonVoidRetunMethodToThrowExWithNewExObj_thenExIsThrown(){
        MyDictionary dictMock =mock(MyDictionary.class);when(dictMock.getMeaning(anyString())).thenThrow(new NullPointerException("Error occurred"));

        dictMock.getMeaning("word");}

    @Test(expected = IllegalStateException.class)
    public voidwhenConfigVoidRetunMethodToThrowExWithNewExObj_thenExIsThrown(){
        MyDictionary dictMock =mock(MyDictionary.class);doThrow(new IllegalStateException("Error occurred")).when(dictMock).add(anyString(),anyString());

        dictMock.add("word","meaning");}

2 Spy对象模拟异常

Spy对象模拟异常的方式与Mock对象相同，如下：

@Test(expected = NullPointerException.class)
public voidgivenSpy_whenConfigNonVoidRetunMethodToThrowEx_thenExIsThrown(){
    MyDictionary dict = new MyDictionary();
    MyDictionary spy = Mockito.spy(dict);when(spy.getMeaning(anyString())).thenThrow(NullPointerException.class);
 
    spy.getMeaning("word");}