I have a third party class called Person, one method is to return a string:
public class Person<T> {
public String getName(Object<T> obj) {
// some code here
return "some string"
}
And another third party class called SomeClass, one method is to return a Person object:
public class SomeClass {
public <T> Person<T> createPerson(Object obj) {
// some code here
return new Person<T>(....)
}
}
My class that uses the above two classes to create a person first, then get person's name. I can't make changes to MyClass because it has been system tested successfully:
public class MyClass {
public String myMethod() {
Person<T> person = someClass.createPerson(obj);
return person.getName(...);
// NullPointerException when junit because "person" object is null
}
}
Now I am working on junit to test MyClass to satisfy the code coverage requirements. For some reason, it always gave me NullPointer exception when person.getName() is called by junit.
public class MyClassTest {
#MockBean
private SomeClass someClass;
#Autowired
private MyClass myClass;
#Test
public void test(){
Person<Student> studentPerson =
(Person<Student>)Mockito.mock(Person.class);
Mockito.when(someClass.createPerson(ArgumentMatchers.any()))
.thenReturn(studentPerson);
Mockito.when(studentPerson.getName(ArgumentMatchers.any()))
.thenReturn("some data");
// call real method
myClass.myMethod(); // failed with NullPointerException
I am not sure why studentPerson is not mocked correctly which caused a NullPointerException becacuse it's Null. Can someone please help? Thanks.
I have seen there are similar question already exist in SO , I tried all the solution , but couldn't fix my problem , as I am new to tdd
I have a class like this
public class AppUpdatesPresenter {
public void stopService() {
ServiceManager.on().stopService();
}
}
I have the test class like this
#RunWith(MockitoJUnitRunner.class)
public class AppUpdatesPresenterTest {
#Mock
AppUpdatesPresenter appUpdatesPresenter;
#Mock
ServiceManager serviceManager;
#Mock
Context context;
#Test
public void test_Stop_Service() throws Exception {
appUpdatesPresenter.stopService();
verify(serviceManager,times(1)).stopService();
}
}
When I tried to test that , if I call stopService() method , then ServiceManager.on().stopService(); called at least once .
But I am getting the following error
Wanted but not invoked:
serviceManager.stopService();
-> at io.example.myapp.ui.app_updates.AppUpdatesPresenterTest.test_Stop_Service(AppUpdatesPresenterTest.java:103)
Actually, there were zero interactions with this mock.
Not sure whats gone wrong .
When you call appUpdatesPresenter.stopService();, nothing happened as you didn't tell it what should be happened.
To make your test pass, you need stubbing the appUpdatesPresenter.
#Test
public void test_Stop_Service() throws Exception {
doAnswer { serviceManager.stopService(); }.when(appUpdatesPresenter).stopService()
appUpdatesPresenter.stopService();
verify(serviceManager).stopService();
}
Btw, the above test is meaningless as you stub all the things.
To make the test case meaningful, you should inject the ServiceManager instead of coupling it with AppUpdatePresenter.
public class AppUpdatesPresenter {
private final ServiceManager serviceManager;
public AppUpdatesPresenter(ServiceManager serviceManager) {
this.serviceManager = serviceManager;
}
public void stopService() {
sm.stopService();
}
}
Then make the AppUpdatesPresenter under test.
#InjectMock AppUpdatesPresenter appUpdatesPresenter;
Now the test case doesn't rely on canned interaction but real implementation of your code.
#Test
public void test_Stop_Service() throws Exception {
appUpdatesPresenter.stopService();
verify(serviceManager).stopService();
}
I have a method whose JUnit test case I have to write. It just calls the main processing method of the project and does nothing else. Also, the main processing method also has return type as void.
How shall I test such a "method1"?
public void method1() {
obj1.mainProcessingMethod():
}
Given a class:
public class A {
private Obj obj1;
public void method1() {
obj1.mainProcessingMethod();
}
public void setObj1(Obj obj1) {
this.obj1 = obj1;
}
}
In test for this class, the only thing to test would be verification whether method obj1.mainProcessingMethod() was invoked exactly once.
You can achieve this with Mockito.
import org.junit.Test;
import org.mockito.Mockito;
public class ATest {
private Obj obj1 = Mockito.mock(Obj.class);
private A a = new A();
#Test
public void testMethod1() {
a.setObj1(obj1);
a.method1();
Mockito.verify(obj1).mainProcessingMethod();
}
}
Here you create a mock object for class Obj, inject it into instance of A, and later use mock object to check which method invocations it recorded.
Inside the test you need to verify that the method mainProcessingMethod(): is called on the object obj1.
you can use something like
Mockito.verify(yourMockObject);
I’m using Mockito 1.9.5. How do I mock what is coming back from a protected method? I have this protected method …
protected JSONObject myMethod(final String param1, final String param2)
{
…
}
However, when I attempt to do this in JUnit:
final MyService mymock = Mockito.mock(MyService.class, Mockito.CALLS_REAL_METHODS);
final String pararm1 = “param1”;
Mockito.doReturn(myData).when(mymock).myMethod(param1, param2);
On the last line, I get a compilation error “The method ‘myMethod’ is not visible.” How do I use Mockito to mock protected methods? I’m open to upgrading my version if that’s the answer.
This is not an issue with Mockito, but with plain old java. From where you are calling the method, you don't have visibility. That is why it is a compile-time issue instead of a run-time issue.
A couple options:
declare your test in the same package as the mocked class
change the visibilty of the method if you can
create a local (inner) class that extends the mocked class, then mock this local class. Since the class would be local, you would have visibility to the method.
Responding to the request for a code sample of option 3 from John B's answer:
public class MyClass {
protected String protectedMethod() {
return "Can't touch this";
}
public String publicMethod() {
return protectedMethod();
}
}
#RunWith(MockitoJUnitRunner.class)
public class MyClassTest {
class MyClassMock extends MyClass {
#Override
public String protectedMethod() {
return "You can see me now!";
}
}
#Mock
MyClassMock myClass = mock(MyClassMock.class);
#Test
public void myClassPublicMethodTest() {
when(myClass.publicMethod()).thenCallRealMethod();
when(myClass.protectedMethod()).thenReturn("jk!");
}
}
You can use Spring's ReflectionTestUtils to use your class as it is and without needing of change it just for tests or wrap it in another class.
public class MyService {
protected JSONObject myProtectedMethod(final String param1, final String param2) {
return new JSONObject();
}
public JSONObject myPublicMethod(final String param1) {
return new JSONObject();
}
}
And then in Test
#RunWith(MockitoJUnitRunner.class)
public class MyServiceTest {
#Mock
private MyService myService;
#Before
public void setUp() {
MockitoAnnotations.initMocks(this);
when(myService.myPublicMethod(anyString())).thenReturn(mock(JSONObject.class));
when(ReflectionTestUtils.invokeMethod(myService, "myProtectedMethod", anyString(), anyString())).thenReturn(mock(JSONObject.class));
}
}
Something like following worked for me, using doReturn() and Junit5's ReflectionSupport.
[Note: I tested on Mockito 3.12.4]
ReflectionSupport.invokeMethod(
mymock.getClass()
// .getSuperclass() // Uncomment this, if the protected method defined in the parent class.
.getDeclaredMethod("myMethod", String.class, String.class),
doReturn(myData).when(mymock),
param1,
param2);
John B is right, this is because the method you're trying to test is protected, it's not a problem with Mockito.
Another option on top of the ones he has listed would be to use reflection to gain access to the method. This will allow you to avoid changing the method you are testing, and avoid changing the pattern you use to write tests, and where you store these tests. I've had to do this myself for some tests where I was not allowed to change the existing code base which included a large number of private methods that needed to be unit tested.
These links explain Reflection and how to use it very well, so I will link to them rather than copy:
What is reflection and whit is it useful
How to test a class that has private methods, fields, or inner classes
WhiteBox.invokeMethod() can be handy.
public class Test extend TargetClass{
#Override
protected Object method(...) {
return [ValueYouWant];
}
}
In Spring, you can set it high high-priority like this:
#TestConfiguration
public class Config {
#Profile({"..."})
#Bean("...")
#Primary // <------ high-priority
public TargetClass TargetClass(){
return new TargetClass() {
#Override
protected WPayResponse validate(...) {
return null;
}
};
}
}
It is the same to override the origin bean.
I have two test functions and for each I want to have different #Before methods. How to achieve this ?
Although it seems to be convenient to organize all the test under the same class, for your case I think the best option is to separate the tests into different classes, each one with his corresponding setUp.
An alternative (I prefer the previous option) could be call the setUp directly in your test method, like the example as follows:
public class FooTest {
public void setUpMethod1() {
// do setUp things
}
public void setUpMethod2() {
// do setUp things
}
#Test
public void testMethod1() {
setUpMethod1();
// Test
}
#Test
public void testMethod2() {
setUpMethod2();
// Test
}
}
Only as a curiosity (IMO not recomended for your case), you can override the default junit RunListener with your own implementation. Method testStarted is executed before every test and you have access to class and methodName to be able to identify the running test. Dummy sample:
public class MyRunListener extends RunListener {
#Override
public void testStarted(Description description) throws Exception {
//...
Class testClass = description.getClass();
String methodName = description.getMethodName();
//...
}
}
Hope it helps.