Junit 使用PowerMock的模拟方法中的NPE

我希望使用PowerMock模拟方法调用的输出。我的班级是这样的：

    public class TestEasyMock {

    private static TestEasyMock TEST_INSTANCE = new TestEasyMock();

    public static TestEasyMock getInstance() {
        return TEST_INSTANCE;
    }

    private Cache<String, String> first = CacheBuilder.newBuilder().
            maximumSize(8192).expireAfterWrite(30, TimeUnit.MINUTES).build();
    private Set<String> second = new TreeSet<String>();

    public String testMethod (String testParam) {
        return first.getIfPresent(testParam);
   }
}

知道为什么会这样吗

---

谢谢

当您使用PowerMock.createStrictPartialMockforAllMethodsCept（TestEasyMock.class，“testMethod”），您指定testMethod不应被模拟。请参阅PowerMock API文档中的

1）确切的堆栈跟踪是什么？2）

TestUtils.replaceString（“可替换”）是如何实现的适合？
@RunWith(PowerMockRunner.class)
@PrepareForTest({TestEasyMock.class})
public class EasyMockTest {
    @Test
    public void firstTest (){

    suppress(constructor(TestEasyMock.class));
        TestEasyMock testObject = PowerMock.createStrictPartialMockForAllMethodsExcept(TestEasyMock.class, "testMethod");
        EasyMock.expect(testObject.testMethod("blabla")).andReturn("blaTwice");
        EasyMock.replay(testObject);

        String result = TestUtils.replaceString("replaceable");
        assertEquals("replaceable(blaTwice)", result);

    }
}