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When you mock a class in mockito framework, do you stand up actual mock class manually?

I am fairly new to mockito framework. I've been reading upon multiple tutorials in regards to it. One of them I was following is this: https://www.tutorialspoint.com/mockito/mockito_first_application.htm
There is a statement creating a mock of Stock Service.
In this example, we've created a mock of Stock Service to get the dummy price of some stocks
My question is Stock Service is a real service class or mock service class you have to manually stand up for mimicking the real service class. I am a bit confused. Having basic understanding of junit framework. What I had practiced before was if there is a service class Foo then I used actual class that provides all the exposed methods.
public class Foo {
public Foo() { } // construtor
public String returnAddress(String userId) {
// ...
return dataAccesobj.getAddress(userId);
}
}
Calling foo.returnAddress(..) in unit test if I remember right.
The reason I am asking this question is while I was working with mockitoto create a test method for a class, I ran into a unique(?) challenge.
I started with a real service class which depends on its super class constructor to return its instance. The challenge I ran into was this super class constructor initiates DB connection and loading/parsing properties files which I do not need for my test. I was thinking about how to prevent DB connection and loading/reading prop files....
I thought I read from one of mockito tutorials you can isolate testing without having such services. I tried with #Mock and #Spy (not fully understanding well still what they are for..) but it didn't make a difference for output (maybe I misused those annotations).
So what I did was actually creating fake/mock class out of real service class (e.g. Foo) by simply copying it and renamed it as FooMock and put it in src/test/java folder in where unit test class is running from. I kept the mock class exactly same as the real service class except taking out unwanted logic such as db connection or loading/reading prop file for env specific. By doing that I was able to test one of exposed methods that read ldap directory...
I am sorry I got digressed but hope my point is clear at this point. I am not sure the way I handled this situation is right or wrong. I'd appreciate experienced engineers would clarify the way I handled the matter is acceptable in mockito way or not. If not, then plz advise me best way to handle it.

With Mockito,
a mock is an implementation of a wrapper class.
The mock object "wraps" the target of the mock
(the service in your example)
and allows you to define functionality of each method.
There are two mocked functionality options with Mockito;
call the wrapped method and don't call the wrapped method.
I don't know when it would make sense to call the wrapped method,
so I always use don't call the wrapped method.
After you create the mock,
use the Mockito.doReturn(returnvalue).when(mockObject).method(method parameters) method to mock functionality.
Edit: some more info.
I will assume that you are using junit v4.
The details of this will differ based on the the junit major release number,
but the actual work will be the same.
Use annotations to define your Mock objects (#Mock),
except in a few special cases.
This will create mocks of non-final classes,
abstract classes,
and interfaces.
Create a "before-test" method using the #Before annotation;
I traditionally name this method preTestSetup,
but the actual name does not matter.
Call MockitoAnnotations.initMocks(this) as the first line of code
in the "before-test" method.
This will find the #Mock annotations and instantiate a mock for each.
Use the ReflectionTestUtils.setField method to inject the mocks into your object (assuming that you don't have setter methods,
which I traditionally don't like).
Define the mocked functionality of each method using the Mockito.doReturn(returnvalue).when(mockObject).method(method parameters) technique.
Here is some example code
(caveat:
this should be fully functional,
but I did not compile it):
public interface MyService
{
String blammy(SomeParameter parameter);
}
public class UsesMyService
{
#Autowired
private MyService myService;
public String kapow(final SomeParameter parameter)
{
return myService.blammy(parameter);
}
}
public class UnitTestUsesMyService
{
private UsesMyService classToTest;
#Mock
private MyService mockMyService;
#Mock
private SomeParameter mockSomeParameter;
#Before
public void preTestSetup()
{
MockitoAnnotations.initMocks(this);
classToTest = new UsesMyService();
doReturn("Blam").when(mockMyService).blammy(mockSomeParameter);
ReflectionTestUtils.setField(
classToTest,
"myService",
mockMyService);
}
#Test
public void kapow_allGood_success()
{
final String actualResult;
actualResult = classToTest.kapow(mockSomeParameter);
assertNotNull(actualResult); // Not strictly necessary.
assertEquals(
"Blam",
actualResult);
}
}

Mockito: Detect when a method on a private resource is invoked

I need to write a test for this class. I need to verify that when the size of the list is exactly 2 then the modelService.save is called. Is it also possible to get to the object productModel?
I don't know where to start.
public class SoldMaterialPrepareInterceptor implements PrepareInterceptor<SoldMaterialModel> {
#Resource
private ModelService modelService;
#Override
public void onPrepare(SoldMaterialModel soldMaterialModel, InterceptorContext interceptorContext) throws InterceptorException {
setSAPSubstance(soldMaterialModel);
}
private void setSAPSubstance(SoldMaterialModel soldMaterialModel) {
ProductModel productModel = soldMaterialModel.getBaseProduct();
Set superCatagoriesList = [....]// gets the list somehow
if (superCatagoriesList.size() == 2) {
productModel.setSupercategories(superCatagoriesList);
modelService.save(productModel);
}
}
}

It is not a problem that the modelService field is private, it is a class field for which private access modifier is usually expected. You need to check the invocation of its save() method, which in turn cannot be private, otherwise it would not be possible to call it from the interceptor class.
As for the test, assuming the superCatagoriesList (which is actually a Set and not a List and also should be generic) gets its content directly or indirectly (e.g. through productModel) from the soldMaterialModel parameter, your task is to write a test, which populates soldMaterialModel with such values so that superCatagoriesList.size() will be 2, and then you can verify that the modelService.save() method was called exactly once with e.g. something like
Mockito.verify(modelService).save(any(ProductModel.class));

I found that when it is difficult to test a method most often there is a design problem of the code I am testing. I suggest a minor to refactoring first: move setSAPSubstance to SoldMaterialModel class and make it public. That is where that method needs to be (see feature envy). Of course modelService.save(productModel); will stay in the interceptor and it will be called only if needed.
Then you will only have to test the two public methods

Is that the whole class? Then I think I see the issue. There are no non-private ways to set the ModelService. When the whole app runs, the dependency injection framework uses reflection to set the ModelService. When you run the test, you don't have anyway to inject a mock. You have a few options.
You can add a constructor to SoldMaterialPrepareInterceptor which takes the ModelService as a parameter. Then you can use that in your test. You would probably also have to add a no-argument constructor because that's how your dependency injection framework creates it. Better yet, you could figure out how to configure the framework to use the new constructor that takes the ModelService.
public class SoldMaterialPrepareInterceptor {
// Public constructor if needed for dependency injection
public SoldMaterialPrepareInterceptor () { }
// If just used for test use protected or package private
// If used with dependency injection, use public.
protected SoldMaterialPrepareInterceptor(ModelService modelService){
this.modelService = modelService
}
The test class is usually in the same package as the actual class, so package private or protected scope is enough. Then the test looks something like this (Assuming Mockito and Junit. Logically, Spock and other frameworks would be similar):
ModelService modelService = Mockito.mock(ModelService.class);
SoldMaterialPrepareInterceptor interceptor = new SoldMaterialPrepareInterceptor(modelService);
// setup SoldMaterialModel and InterceptorContext
interceptor.onPrepare(soldMaterialModel, interceptorContext);
Mockito.verify(modelService, Mockito.times(0)).save(soldMaterialModel);

Non static #BeforeClass equivalent when Spring unit test runner? [duplicate]

Are there any best practices to get Junit execute a function once in a test file , and it should also not be static.
like #BeforeClass on non static function?
Here is an ugly solution :
#Before void init(){
if (init.get() == false){
init.set(true);
// do once block
}
}
well this is something i dont want to do , and i am looking for an integrated junit solution.

A simple if statement seems to work pretty well too:
#RunWith(SpringJUnit4ClassRunner.class)
#ContextConfiguration(locations = {"classpath:test-context.xml"})
public class myTest {
public static boolean dbInit = false;
#Autowired
DbUtils dbUtils;
#Before
public void setUp(){
if(!dbInit){
dbUtils.dropTables();
dbUtils.createTables();
dbInit = true;
}
}
...

To use an empty constructor is the easiest solution. You can still override the constructor in the extended class.
But it's not optimal with all the inheritance. That's why JUnit 4 uses annotations instead.
Another option is to create a helper method in a factory/util class and let that method do the work.
If you're using Spring, you should consider using the #TestExecutionListeners annotation.
Something like this test:
#RunWith(SpringJUnit4ClassRunner.class)
#TestExecutionListeners({CustomTestExecutionListener.class,
DependencyInjectionTestExecutionListener.class})
#ContextConfiguration("test-config.xml")
public class DemoTest {
Spring's AbstractTestExecutionListener contains for example this empty method that you can override:
public void beforeTestClass(TestContext testContext) throws Exception {
/* no-op */
}
NOTE: DO NOT overlook/miss DependencyInjectionTestExecutionListener while adding custom TestExecutionListeners. If you do, all the autowires will be null.

If you don't want to set up static initializers for one time initialization and are not particular about using JUnit, take a look at TestNG. TestNG supports non-static, one-time initialization with a variety of configuration options, all using annotations.
In TestNG, this would be equivalent to:
#org.testng.annotations.BeforeClass
public void setUpOnce() {
// One time initialization.
}
For teardown,
#org.testng.annotations.AfterClass
public void tearDownOnce() {
// One time tear down.
}
For the TestNG equivalent of JUnit 4's #Before and #After, you can use #BeforeMethod and #AfterMethod respectively.

Easily use #BeforeAllMethods/#AfterAllMethods annotations to run a method inside the instance context (non-static), where all injected values will be available.
There is a special testing library for this:
https://mvnrepository.com/artifact/org.bitbucket.radistao.test/before-after-spring-test-runner/0.1.0
https://bitbucket.org/radistao/before-after-spring-test-runner/
The only limitation: works only for Spring testing.
(I'm the developer of this testing library)

I've never tried but maybe you can create a no-argument constructor and call you function from there?

The article discuss 2 very nice solutions for this problem:
"clean" junit with custom Runner (using interface but you could extend it with a custom annotation e.g. #BeforeInstance)
Spring execution listeners as mentioned by Espen before.

UPDATE: Please see the comment by Cherry for why the suggestion below is flawed. (Am keeping the answer on here rather than deleting as the comment may provide useful information to others as to why this doesn't work.)
Another option worth considering if using dependency injection (e.g. Spring) is #PostConstruct. This will guarantee dependency injection is complete, which wouldn't be the case in a constructor:
#PostConstruct
public void init() {
// One-time initialization...
}

Just use #BeforeClass:
#BeforeClass
public static void init() {
}
It doesn't make sense for init to be non-static because each test is run in a separate instance. The instance
that init is run on would not match the instance of any test.
The only reason that you might want it to be non-static is to override it in subclasses, but you can do this
with static methods too. Just use the same name, and only the subclass init method will be called.

How to mock a protected method of 3rd party code

Using Mockito I want to mock a property of a class so I can verify the output
public class MyClass extends ThirdPartyFramework {
Output goesHere;
#Override
protected setup(){
goesHere = new Output();
}
//...
}
public abstract class ThirdPartyFramework {
protected setup(){...}
//...
}
I need to inject a mock of the Output class so I can validate that my code wrote the correct output.
But I can't just #InjectMock because the setup() method is called
mid-runtime and overwrites my injection.
And I can't just make setup public in MyClass because the test code I'm working
with is generic and needs to work for all subclasses of
ThirdPartyFramework, so I only have a reference to ThirdPartyFramework, meaning setup() is protected.

Are you set on Mockito? I am asking since Mockito FAQMockito FAQ states that it doesn't support mocking static methods, which I guess you'd need in this case for the setup method to create your mock instead of real Output.
I have used PowerMock for a similar scenario:
whenNew(NewInstanceClass.class).withArguments(any()).thenReturn(mockObject);
which says that each time a NewInstanceClass gets created my mockObject be returned no matter what constructor arguments had been used and who constructed NewInstanceClass at what time.
In PowerMock docs I've also found following example:
PowerMock.expectNew(NewInstanceClass.class).andReturn(mockObject)
Actually you could use it even if you are bound to Mockito, PowerMock contains helpers for Mockito to solve exactly this problem that let you use Mockito for all tests and PowerMock to mock constructing objects. Like this:
whenNew(Output.class).withNoArguments().thenReturn(yourOutputMock);

I ended up solving this by wrapping ThirdPartyFramework and placing that class in the same package as the ThirdPartyFramework class.
That way I could mock the protected methods with Mockito. Then I was able to use #InjectMock to inject a mock of the Output object and control its method calls via that mock.

How about adding a setter for "goesHere" and then have setup() check and only change the value of goesHere if its null. This way you could inject a value in testing that would not be overridden. Something like:
protected void setGoesHere( Output output ){
goesHere = output;
}
#Override
protected void setup(){
if(goesHere != null) goesHere = new Output();
}
Hope this helps.

How to avoid inheritance in JUnit test cases?

I have a number of test cases in JUnit. All of them need the same code to be executed in their #BeforeClass static method. It's a code duplication and I'm trying to get rid of it. A dirty way of doing this is by inheritance. Are there any other mechanisms in JUnit, that may help?
PS. I wrote this blog post about this very subject: http://www.yegor256.com/2015/05/25/unit-test-scaffolding.html

The JUnit way to compose reusable code (instead of inheriting from it) are Rules.
See https://github.com/junit-team/junit/wiki/Rules
Here is a dumb sample, but you'll get the point.
import org.junit.rules.TestRule;
import org.junit.runners.model.Statement;
import org.junit.runner.Description;
public class MyTestRule implements TestRule {
#Override
public Statement apply(final Statement statement, Description description) {
return new Statement() {
public void evaluate() throws Throwable {
// Here is BEFORE_CODE
try {
statement.evaluate();
} finally {
// Here is AFTER_CODE
}
}
};
}
}
You can then use your TestRule like this:
import org.junit.Rule;
public class MyTest {
#Rule
public MyTestRule myRule = new MyTestRule();
}
BEFORE_CODE and AFTER_CODE will then be executed around each of your test methods.
If you need to run your code only once per class, use your TestRule as a #ClassRule:
import org.junit.ClassRule;
public class MyTest {
#ClassRule
public static MyTestRule myRule = new MyTestRule();
}
Now, BEFORE_CODE and AFTER_CODE will be executed around each of your test class.
#Rule field is not static, #ClassRule field is.
A #ClassRule can be declared in a Suite too.
Note that you can declare several rules in a single test class, that's how you compose test lifecycles at test-suites, test-classes and test-methods levels.
A Rule is an object that you instanciate in your test classes (statically or not). You can add contructor parameters if needed.
HTH

If the method is some kind of utility, then separate it out to a different class with a static method and call that method in your #BeforeClass.
I emphasize on the fact that don't use inheritance just because it solves your problem, use it when doing so creates sense in your class hierarchy.

You may create test runner
public class MyTestRunner extends BlockJUnit4ClassRunner {
#Override
protected Object createTest() throws Exception {
Object test = super.createTest();
doStuff();
}
public void doStuff(){
//common code
}
}
#RunWith(MyTestRunner.class)
public class MyTest1{
#Test
public void test1(){
//test method
}
}

Static methods aren't inherited, so inheritance isn't an option by default. If you mean you're moving the method to a common parent class, then that seems a poor choice since you only get one parent in Java. A test support class of some sort would seem more appropriate. It's also possible that you're seeing a need for a parameterized test.

There is absolutely nothing wrong with inheritance in this case, it's actually the only way to avoid repeating this code in each subclass. The fact that #BeforeClass methods have to be declared static in JUnit is unfortunate, but that shouldn't stop you. Extend the class and you have the initialization code automatically run for you without having to do anything.

If each and every class needs to have a #BeforeClass annotated method that is exactly the same as every other, then inheritance does not feel that wrong to me. If each of these initializing methods simply share some code, you could make a TestUtil class with some shared behavior and make calls to this shared behavior from each of the #BeforeClass methods.

I think if the classes has "is-a" relation, inheritance is reasonable.
If the base class is MyBeforeClass which defines #BeforeClass method, and MyTestClass1 "is-a" MyBeforeClass, MyTestClass1 extends MyBeforeClass is OK.

Depending on the nature of the setup code, you can potentially put all your tests in a test suite and have the setup code run there. The downside to this is that you cannot run tests individually (since the test depends on the setup code).