"mvn test"没有执行@Mock注解的方法

Question

我有一个测试 class 看起来像这样：

import org.junit.Before;
import org.junit.Test;
import org.mockito.Mock;
import org.mockito.Mockito;
import org.mockito.MockitoAnnotations;

public class SomeTest {
    @Mock
    Object someObj;

    @Before
    public void before() {
        MockitoAnnotations.openMocks(this);
    }

    @Test
    public void testNullPointer() {
        Mockito.when(someObj.toString()).thenReturn("1");
    }
}

当我在这个项目的根目录下运行mvn clean test时，说testcase触发了NullPointerException，stack tree显示someObj为null。
我正在使用 org.mockito::mockito-core::4.0.0 和 junit::junit::4.13.0.
似乎没有执行 before() 方法。任何想法为什么？提前谢谢。

Answer 1

您的 class 上缺少注释：

@RunWith(MockitoJUnitRunner.class)
public class SomeServiceTest {
    ...
}

Answer 2

当运行这个测试时，你会在堆栈跟踪上方得到这个错误：

testNullPointer(org.example.SomeTest)  Time elapsed: 0.368 sec  <<< ERROR!
org.mockito.exceptions.misusing.MissingMethodInvocationException:
when() requires an argument which has to be 'a method call on a mock'.
For example:
    when(mock.getArticles()).thenReturn(articles);

Also, this error might show up because:
1. you stub either of: final/private/equals()/hashCode() methods.
   Those methods *cannot* be stubbed/verified.
   Mocking methods declared on non-public parent classes is not supported.
2. inside when() you don't call method on mock but on some other object.

这里有趣的部分是第一个项目符号 - 您不能对 hashCode 方法进行存根。如果你用一些可以存根的方法替换它，测试就会通过。例如：

Mockito.when(someObj.toString()).thenReturn("yay!");

"mvn test"没有执行@Mock注解的方法

"mvn test" did not execute @Mock annotated method

java

junit

unit-testing

mockito

maven