I am facing an issue with Mockito junit testing. I am new to it and am a bit confused with the problem I am facing. Any help on this would be appreciated.
class Activity{
public void firstMethod(){
String str = secondMethod();
}
public String secondMethod(){
String str = null;
/* some Code */
return str;
}
}
Getting exception :
*org.mockito.exceptions.misusing.NotAMockException:
Argument passed to when() is not a mock!*
in the below code
class ActivityTest(){
Activity act;
#Before
public void setup(){
act = new Activity();
}
#Test
public void testFirstMethod(){
Mockito.doReturn(Mockito.anyString()).when(act).secondMethod();
act.firstMethod();
verify(act).secondMethod();
}
}
I am aware that activity is not a mock but I am not sure for a way around this as secondMethod() is a method in the same class. I need to write rule for secondMethod() as I have already done its Unit Testing. The definition of secondMethod() consists has external dependencies. Should I be mocking the external dependencies present in secondMethod() and writing rules for them rather than rule for secondMethod()?
I found this post:
Mockito Spy'ing on the object being unit tested
However separating the secondMethod() into a different class does not make sense. My method is related to this class. Creating a different class for testing does not seem right to me. Even mocking the actual class using spy() is not the most correct way as already explained in the post.
I don't think I should be creating a mock of the Activity class as that is the class I am testing. I would really appreciate help and insights into this.
As you noted, act is not a mock, and therefore you cannot record behavior on it. You could use Mockito.spy to, well, spy (or partially mock) the act object so that you only record the behavior of secondMethod and execute the actual code for firstMethod.
Note, however, that matchers can't be used in doReturn calls regardles of how you're mocking or spying your object. A return value must be a concrete object.
class ActivityTest() {
Activity act;
#Before
public void setup(){
act = Mockito.spy(new Activity()); // Here!
}
#Test
public void testFirstMethod(){
Mockito.doReturn("someString").when(act).secondMethod();
act.firstMethod();
verify(act).secondMethod();
}
}
A slightly more elegant syntax allows you to use annotations instead of explicitly calling Mockito.spy, but it's a matter of taste really:
#RunWith(MockitoJUnitRunner.class)
class ActivityTest() {
#Spy
Activity act = new Activity();
#Test
public void testFirstMethod(){
Mockito.doReturn("someString").when(act).secondMethod();
act.firstMethod();
verify(act).secondMethod();
}
}
There is no reason to mock anything in this example. Since there are no dependencies and both methods are public, you can test them directly.
public class ActivityTest() {
private Activity act = new Activity();
#Test
public void testSecondMethod(){
assertEquals("expected-value", act.secondMethod());
}
#Test
public void testFirstMethod() {
act.firstMethod();
// success if no exception occurs
}
}
Since firstMethod does not have any detectable effect on the Act instance, nor on any dependency (since there are none) you can simply call the method and be satisfied if no exception is thrown. One could also reason that such a method should not be tested at all.
I assume the example given is a simplification of a class where calling firstMethod actually does have side effects, who knows...
Here are some hints:
Mock the Activity.
Tweak the behavior of secondMethod with when / then / doReturn
Use doCallRealMethod when firstMethod is invoked.
Hope it helps.
Related
My question is about testing a class that implements many interfaces. For example, I have this class:
public class ServiceControllerImpl extends ServiceController implements IDataChanged, IEventChanged {
}
Now there are two ways for testing. The first is testing directly on the concrete class. That means the object type is the concrete class rather than the interface.
public class ServiceControllerImplTest {
ServiceControllerImpl instance;
#Before
public void setUp() {
instance = new ServiceControllerImpl();
// you can bring this instance anywhere
}
}
The second way is testing on the interface only. We must typecast this object to all interfaces it implements.
public class ServiceControllerImplTest {
ServiceController instance; // use interface here
IDataChanged dataChangeListener;
#Before
public void setUp() {
instance = new ServiceControllerImpl();
dataChangeListener = (IDataChanged) instance;
// instance and dataChangeListener "look like" two different object.
}
}
I prefer the second solution because maybe in future we can change the interface it implements to other objects, so using the concrete class might lead to failing tests in the future. I don't know the best practice for this problem.
Thanks :)
I prefer second solution because in reality, maybe in future we can change the interface it implements to other objects, so force using concreted class maybe leads to fail test in the future.
I guess it will lead to failed tests anyway, because you usually test that assertions are true or false. The question is: Do that tests apply to any IDataChanged or do these assertions only apply to the ServiceControllerImpl?
If the assertions only apply to the ServiceControllerImpl it doesn't matter if you use an IDataChanged instead of an ServiceControllerImpl, because you must edit the test when you use another IDataChanged object - different assertions. The test will fail if you use another object.
The way you setup unit tests Itself gives you an answer. A unit test usually tests one class in isolation. This means that you mock the environment. But mocking the environment means that you know the dependencies of the class you test and this are implementation details. So your test is written on an implemtation basis rather than only the interface.
It's possible to write tests that only test an abstract api - like an interface. But this usually means that your tests are abstract too. E.g.
public abstract class SetTest {
#Test
public void addAlreadyExistentObject(){
Set<String> setUnderTest = createSetUnderTest();
Assert.assertTrue(setUnderTest.isEmpty());
boolean setChanged = setUnderTest.add("Hello");
Assert.assertTrue(setChanged);
setChanged = setUnderTest.add("Hello");
Assert.assertFalse(setChanged);
Assert.assertEquals(setUnderTest.size(), 1);
}
protected abstract Set<String> createSetUnderTest();
}
You can then extend these abstract tests to test the api for concrete classes. E.g.
public class HashSetTest extends SetTest {
#Override
protected Set<String> createSetUnderTest() {
return new HashSet<String>();
}
}
In this case you can replace the implementation and the test must remain green.
But here is another example of an abstract api when replacing the object under test does not really make sense.
What about writing a test for all Runnables?
public class RunnableTest {
#Test
public void run(){
Runnable runnable = ...;
// What to test here?
// run is invoked without throwing any runtime exceptions?
runnable.run();
}
}
As you can see it does not make sense in some cases to write tests in a way so that you can easily replace the object under test.
If an api like the Set api defines a concrete state handling you can write abstract tests that test this.
JayC667 already correctly answered that it's best to refer to a class through its supertype(s) in tests of methods defined by those types. But I'd change the way you did that a bit to avoid casting:
public class ServiceControllerImplTest {
ServiceController controller;
IDataChanged dataChangeListener;
#Before
public void setUp() {
instance = new ServiceControllerImpl();
controller = instance;
dataChangeListener = instance;
}
}
I am writing an integration test using mockito.
The unit under test is connected to a mocked object (objA) through an interface. The functionality that I am trying to mimic happens when the mocked objected fires an event and the unit under test is listening to it.
The interface:
public interface MyInterfaceAPI{
void fireyMyEvent(String msg);
}
The unit under test:
public class UnitUnderTest{
ObjA objA;
public UnitUnderTest(ObjA objA_t) {
objA = objA_t;
objA.addMyListener(new addMyHandler());
}
class addMyHandler implements MyInterfaceAPI{
#Override
public void fireyMyEvent(String msg) {
System.out.println(msg);
};
};
};
The test:
public class MyTest {
#org.junit.Test
public void run() {
ObjA mockObjA = mock(ObjA .class);
UnitUnderTest spyController = Mockito.spy(new UnitUnderTest());
MyInterfaceAPI mo2uut= mock(MyInterfaceAPI.class);
mo2uut.fireyMyEvent("hello from test");
}
}
My question is in the test, how do I connect the mo2uut ('mocked object' to 'unit under test') to the addMyHandler class implementation of MyInterfaceAPI inside the UnitUnderTest?
I am clearly missing something, but I am not sure what.
You have 2 schools on unit testing: The London / Mockist school, and the Detroit school.
If you want to use mocks, you must use dependency injection, so you can replace the dependencies with mocks. I think most people following the Detroit school would agree on this too, just because using dependency injection "is a good thing" (tm).
What you can do is to pass an instance of ObjA to UnitUnderTest in the constructor; Or alternatively (if ObjA is a collection) add the method UnitUnderTest.addListener(), where you pass an instance of a handler. With these 2 approaches, you'll be injecting a handler.
About using powermock: Powermock is a beast better used on old projects that have very little unit testing and their dependencies are a mess. If you are coding this now, using power mock is wrong (in the spirit of fairness, this is a biased idea, but it's shared with many other people).
Edit
Now I get your question! And I think that you're trying to test too much in one unit test and that causes the problem. Again, the mockist school talks about testing interactions... that's the key point. So in the test for UnitUnderTest the only interaction is with ObjA to set the handler, and that's the end of the story.
You'll probably have another test for ObjA to ensure that all handlers are invoked.
Now the last bit is how to test the code of the handler. But before that, please appreciate how independent each test is, as you're testing the interactions (and any logic in the code), but not more than 1 thing.
About the handler... you might not like this, but you have to make that class accessible, either make it public or extract it to another public class. If you extract it, you can put in an internal package so it's clear that the class shouldn't be used by anyone else.
If you have an hour to spare, I would suggest you to watch this great presentation: The Deep Synergy Between Testability and Good Design by Michael Feathers where he goes into a similar example of what you have in your code and why it makes sense to separate it.
Use PowerMock's PowerMockito to intercept the call to the addMyHandler class injecting a mock of MyInterfaceAPI as explained in Ben Kiefer's tutorial on "PowerMockito: Constructor Mocking"
I have managed to make it working. Posting here the fixed code for people who see this in the future.
public interface MyInterfaceAPI{
void fireyMyEvent(String msg);
}
The unit under test:
public class UnitUnderTest{
private ObjA objA;
public MyInterfaceAPI interfaceHandler;
public UnitUnderTest(ObjA objA_t) {
objA = objA_t;
interfaceHandler = new addMyHandler();
objA.addMyListener(interfaceHandler);
}
class addMyHandler implements MyInterfaceAPI{
#Override
public void fireyMyEvent(String msg) {
System.out.println(msg);
};
};
};
The test:
public class MyTest {
#org.junit.Test
public void run() {
ObjA mockObjA = mock(ObjA .class);
UnitUnderTest spyController = Mockito.spy(new UnitUnderTest());
spyController.hnd.fireyMyEvent("hello from test");
}
}
I have got a problem with testing how many times concrete methods (IFunction in the Operation instance) is invoked.
According to:
http://easymock.org/user-guide.html#mocking-annotations
http://www.ibm.com/developerworks/library/j-easymock/
How to use EasyMock expect
I wrote something as:
class Operation{
public double[] calculateSth(IFunction function, int [] t){
for(int i=0 ; i<5 ; i+=1)
function(t, new int[]{1,2,3});
return new double[]{1,2,3};
}
}
interface IFunction{
double f(int[] a, int[]b);
}
class ConcreteF implements IFunction{
double f(int[]a, int[]b){
return 5;
}
}
And my test class:
#TestSubject
Operation op;
#Mock
IFunction function;
#Before
public void setUp() throws Sth{
op=new Operation();
function = EasyMock.createMock(IFunction.class);
}
#Test
public void howManyTimes(){
EasyMock.expect(function.f(EasyMock.notNull(), EasyMock.notNull())
)
.andReturn((double)EasyMock.anyDouble()).times(3);
EasyMock.replay(function);
op.calculateSth(function, new double[]{0,0,0});
//verify
EasyMock.verify(function);
}
Result:
java.lang.NullPointerException
at org.easymock.internal.Injector.injectMocks(Injector.java:80)
at org.easymock.EasyMockSupport.injectMocks(EasyMockSupport.java:624)
at org.easymock.EasyMockRunner.withBefores(EasyMockRunner.java:50)
It's my first time using easymock and i don't know how to fix it ;/
I'll answer this question without going into the details of whether the original method does anything useful (the code doesn't even compile anyway), let alone the test method.
#TestSubject Operation op;
This line is a suspect. I realize that you are instantiating it in the #Before annotated setUp method, but it looks like the Easymock tries to inject the mocks (the ones annotated with #Mock) before it does anything (and understandably so) and blows up since the reference is null at that point.
The annotation support introduced in v3.2 is also seen as a way to eliminate the need for setUp method. But you seem to be mixing both and using it wrongly. Choose one or the other - I'd recommend you to use the annotations.
Quoting the Easymock user guide (this user guide is as good as it can ever be, so be sure read this up before using the library),
#RunWith(EasyMockRunner.class)
public class ExampleTest {
#TestSubject
private ClassUnderTest classUnderTest = new ClassUnderTest(); // 2
#Mock
private Collaborator mock; // 1
#Test
public void testRemoveNonExistingDocument() {
replay(mock);
classUnderTest.removeDocument("Does not exist");
}
}
The mock is instantiated by the runner at step 1. It is then set by
the runner, to the listener field on step 2. The setUp method can be
removed since all the initialization was done by the runner.
public class First {
public First(){
}
public String doSecond(){
Second second = new Second();
return second.doJob();
}
}
class Second {
public String doJob(){
return "Do Something";
}
}
Here I want to test the method "doSecond()" of class "First". For the same, I want to mock the method "doJob" of class "Second".
I know that I can create a mocked instance of class "Second" using the code below.
Second sec = mock(Second.class);
when(sec.doJob()).thenReturn("Stubbed Second");
But I cannot relate this mocked instance with class "First" as of the current code.
Without refactoring the source code, is there any way by which i can achieve the requirement.
Please help.
Take a look at powermock's ability to intercept calls to new and return mocks instead
https://code.google.com/p/powermock/wiki/MockConstructor
This doesn't require changing any sourcecode.
here's the test code where we actually return a mock when First.doSecond() calls new Second()
#RunWith(PowerMockRunner.class)
#PrepareForTest(First.class)
public class TestFirst {
#Test
public void mockSecond() throws Exception{
Second mock = PowerMockito.mock(Second.class);
PowerMockito.whenNew(Second.class).withNoArguments().thenReturn(mock);
PowerMockito.when(mock.doSecond()).thenReturn("from mock");
First first = new First();
assertEquals("from mock", first.doSecond());
}
}
It's tricky to mock an instance that you create inside of a method, but it's possible.
Using PowerMock, you can accomplish this with the PowerMock.expectNew() method:
#RunWith(PowerMockRunner.class)
#PrepareForTest(First.class)
public class StackOverflowTest {
#Test
public void testFirst() throws Exception {
Second secondMock = EasyMock.createMock(Second.class);
PowerMock.expectNew(Second.class).andReturn(secondMock);
expect(secondMock.doSecond()).andReturn("Mocked!!!");
PowerMock.replay(secondMock, Second.class);
String actual = new First().doSecond();
PowerMock.verify(secondMock, Second.class);
assertThat(actual, equalTo("Mocked!!!"));
}
}
Effectively, PowerMock is proxying the creation of the new object and substituting whatever value we want when we invoke doSecond().
So, it's possible. However, this is a terrible practice to get into.
One typically wants to mock objects if they involve an outside concern, such as another layer (i.e. database, validation), or if the desired output is coming from other objects that are injected but are safe enough to consider tested.
If your method is capable of getting or retrieving data from a non-injectable source, you should not want to mock that out.
Considering that your method is simple and straightforward, you should really not need to do any mocks here at all. But if you felt that you were forced to, you could do one of a few things:
Create a factory for the creation of Second, and mock the results of the returning factory object with Mockito.
Pass in an instance of Second to that method, and use Mockito as the mock instance.
Declare it as a field (i.e. injected dependency), and use Mockito.
For completeness, here is how the test can be written with the JMockit mocking API, without any refactoring of the original code under test:
public class ExampleTest
{
#Test
public void firstShouldCallSecond(#Mocked final Second secondMock) {
new NonStrictExpectations() {{
secondMock.doJob(); result = "Mocked!!!";
}};
String actual = new First().doSecond();
assertEquals("Mocked!!!", actual);
}
}
I'm new to using Mockito and am trying to understand a way to make a unit test of a class that relies on injected dependencies. What I want to do is to create mock objects of the dependencies and make the class that I am testing use those instead of the regular injected dependencies that would be injected by Spring. I have been reading tutorials but am a bit confused on how to do this.
I have one the class I want to test like this:
package org.rd.server.beans;
import org.springframework.beans.factory.annotation.Autowired;
public class TestBean1 {
#Autowired
private SubBean1 subBean1;
private String helloString;
public String testReturn () {
subBean1.setSomething("its working");
String something = subBean1.getSomething();
helloString = "Hello...... " + something;
return helloString;
}
Then I have the class that I want to use as a mock object (rather than the regular SubBean1 class, like below:
package org.rd.server.beans.mock;
public class SubBean1Mock {
private String something;
public String getSomething() {
return something;
}
public void setSomething(String something) {
this.something = something;
}
}
}
I just want to try running a simple test like this:
package test.rd.beans;
import org.rd.server.beans.TestBean1;
import junit.framework.*;
public class TestBean1Test extends TestCase
{
private TestBean1 testBean1;
public TestBean1Test(String name)
{
super(name);
}
public void setUp()
{
testBean1 = new TestBean1();
// Somehow inject the mock dependency SubBean1Mock ???
}
public void test1() {
assertEquals(testBean1.testReturn(),"working");
}
}
I figure there must be some fairly simple way to do this but I can't seem to understand the tutorials as I don't have the context yet to understand everything they are doing / explaining. If anyone could shed some light on this I would appreciate it.
If you're using Mockito you create mocks by calling Mockito's static mock method. You can then just pass in the mock to the class you're trying to test. Your setup method would look something like this:
testBean1 = new TestBean1();
SubBean1 subBeanMock = mock(SubBean1.class);
testBean1.setSubBean(subBeanMock);
You can then add the appropriate behavior to your mock objects for whatever you're trying to test with Mockito's static when method, for example:
when(subBeanMock.getSomething()).thenReturn("its working");
In Mockito you aren't really going to create new "mock" implementations, but rather you are going to mock out the methods on the interface of the injected dependency by telling Mockito what to return when the method is called.
I wrote a test of a Spring MVC Controller using Mockito and treated it just like any other java class. I was able to mock out the various other Spring beans I had and inject those using Spring's ReflectionTestUtils to pass in the Mockito based values. I wrote about it in my blog back in February. It has the full source for the test class and most of the source from the controller, so it's probably too long to put the contents here.
http://digitaljoel.nerd-herders.com/2011/02/05/mock-testing-spring-mvc-controller/
I stumbled on this thread while trying to set up some mocks for a slightly more complicated situation and figured I'd share my results for posterity.
My situation was similar in the fact that I needed to mock dependencies, but I also wanted to mock some of the methods on the class I was testing. This was the solution:
#MockBean
DependentService mockDependentService
ControllerToTest controllerToTest
#BeforeEach
public void setup() {
mockDependentService = mock(DependentService.class);
controllerToTest = mock(ControllerToTest.class);
ReflectionTestUtils.setField(controllerToTest, "dependantService", mockDependentService);
}
#Test
void test() {
//set up test and other mocks
//be sure to implement the below code that will call the real method that you are wanting to test
when(controllerToTest.methodToTest()).thenCallRealMethod();
//assertions
}
Note that "dependantService" needs to match whatever you have named the instance of the service on your controller. If that doesn't match the reflection will not find it and inject the mock for you.
This approach allows all the methods on the controller to be mocked by default, then you can specifically call out which method you want to use the real one. Then use the reflection to set any dependencies needed with the respective mock objects.
Hope this helps someone down the road as it stumped me for a while.