I am trying to write a unit test for a java class that is extending an abstract class? The java class looks sort of like:
public class XYZFilter extends XYZDataFilter{
#Override
protected boolean filterItem(Model d, String sector) {
//method code
return true;
}
}
The junit test class looks like:
import org.junit.Test;
import static org.junit.Assert.assertTrue;
public class XYZFilterTest {
Model m = new Model();
String sector = "SECTOR";
#Test
public void testFilterItem() throws Exception {
System.out.println("\nTest filterItem method...");
XYZFilter f = new XYZFilter();
assertTrue(f.filterItem(m, sector));
}
}
So I'm having a problem with the abstract DataFilter which is extended by the Filter class, as well as the Model class. I believe I need to mock these objects using JMockit but I am having a lot of trouble figuring out how to do this. Any advice is appreciated.
The answer is I needed to have the libraries included, JMockit doesn't handle objects in that way.
Related
I have a class under test whose constructer looks like this :
public class ClassUnderTest {
ClientOne clientOne;
ClientTwo clientTwo;
OtherDependency otherDependency;
#Inject
public ClassUnderTest(MyCheckedProvider<ClientOne> myCheckedProviderOne,
MyCheckedProvider<ClientTwo> myCheckedProviderTwo,
OtherDependency otherDependency) throws Exception {
this.clientOne = myCheckedProviderOne.get();
this.clientTwo = myCheckedProviderTwo.get();
this.otherDependency = otherDependency;
}
.
.
.
}
And the CheckedProvider looks thus :
public interface MyCheckedProvider<T> extends CheckedProvider<T> {
#Override
T get() throws Exception;
}
I could mock the clients, but how do I initialise the providers with my mocked clients.I use a combination of junit and mockito for writing tests.Any inputs would be appreciated.
What you could do is to mock providers rather than clients. ClientOne and ClientTwo are the types you are passing into your generic class, they are not variables and hence not something you want to mock. In contrast, the providers you are passing to the constructor are really variables, and what you need to control (simulate) are the behaviors of these variables.
public class ClassTest {
private static final CientOne CLIENT_ONE = new ClientOne();
private static final ClientTwo CLIENT_TWO = new ClientTwo();
#Mock
private MyCheckedProvider<ClientOne> providerOne;
#Mock
private MycheckedProvider<ClientTwo> providerTwo;
private ClassUnderTest classUnderTest;
#Before
public void setUp() {
when(providerOne.get()).thenReturn(CLIENT_ONE);
when(providerTwo.get()).thenReturn(CLIENT_TWO);
classUnderTest = new ClassUnderTest(providerOne, providerTwo, otherDependency);
}
}
As the other answer suggests, you could easily mock the providers, too.
But youMyCheckedProvider don't have to.
You already have an interface sitting there, so what would prevent you from creating something like
class MyCheckedProviderImpl<T> implements MyCheckedProvider<T> {
and that think takes a T object in its constructor and returns exactly that?
That is more or less the same what the mocking framework would be doing.
I have got a question connected with Mockito framework. Is there any way to mock a field inside a class? Lets say we have got:
#Component
public class A{
#Autowired
B b;
public methodExample(){b.doSth();}
}
class C {
#Autowired
A a;
}
#Test
public void testMethodExample(){...}
}
Is there any possibility to mock B object in order to impose return value of method doSth? I know I can pass mocked object as an argument of constructor but I wonder if there is any other option?
You may take a look at #InjectMocks.
With this annotation Mockito will try to assign the mocks through constructor, property and field, respectively, stopping at the first approach which succeeds.
Thus a unit test for your scenario might look like:
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.runners.MockitoJUnitRunner;
#RunWith( MockitoJUnitRunner.class )
public class c
{
#InjectMocks
A a;
#Mock
B b;
#Test
public void testMethodExample()
{
a.methodExample();
}
}
Some points worth some attention:
#InjectMocks will only take into account the fields annotated with #Mock
It's necessary to use MockitoJUnitRunnerOR call org.mockito.MockitoAnnotations.initMocks(this); in order to create and inject your mocks.
You can provide a protected setter for testing only and have your test package structure mirror the package structure of your main code.
Or you can use the Powermock extension to mock private/protected fields as required.
See
https://code.google.com/p/powermock/wiki/BypassEncapsulation
#Test
public void testDoSomething(){
A a = new A();
B mockedB = //create a mock;
Whitebox.setInternalState(a, "b", mockedB);
}
Consider the following code (in C# but it could be any other language):
public interface IObjectCopier
{
void Copy<T>(T source, T target);
}
public class Model
{
public string Name { get; set; }
}
public class ViewModel
{
private readonly IObjectCopier _objectCopier;
public ViewModel(IObjectCopier objectCopier)
{
_objectCopier = objectCopier;
}
public Model ViewBindData { get; set; }
public void Load(Model model)
{
_objectCopier.Copy(model, ViewBindData);
}
}
How do I construct a unit test for the Load method? If I mock IObjectCopier then I need to supply a mock implementation of the Copy method. In this example it is trivial but in a real world scenario Model can be large with sub models and the mocking exercise feel like it is just copying what the IObjectCopier implementation does.
The problem is simplified if I could change the Copy method to the following:
T Copy<T>(T source);
As in this case the mock setup is drastically simplified. The problem is that there are view bindings to the Model object and I cannot simply destroy and re-create the object.
Is there an elegant way to get around this problem?
If you're using mocks, then the only thing you care about is that the copier is invoked with the 2 parameters.
So in some sort of pseudo code
test "populates model from view data" {
objectCopiermock = mock(IObjectCopier)
model = new Model() //create empty or use a TestDataBuilder
viewBindData = new viewBindData() //create empty or use a TestDataBuilder
viewModel = new ViewModel(objectCopiermock)
viewModel.viewBindData(viewBindData)
viewModel.Load(model)
verifyMock(objectCopiermock).copy(model, viewBindData)
}
The important thing with mocks is to verify the interactions, and not the values inside model or viewBindData.
If this is confused, don't panic! (tm) - and I would suggest you to read a bit about the difference between the London and Chicaco/Detroit schools of TDD
The below test throws java.lang.IllegalStateException: no last call on a mock available when I don't extend from the PowerMockTestCase.
The error disappears as soon as I extend from PowerMockTestCase. Why exactly is this happening?
import static org.junit.Assert.assertEquals;
import org.easymock.EasyMock;
import org.powermock.api.easymock.PowerMock;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.testng.PowerMockTestCase;
#PrepareForTest({ IdGenerator.class, ServiceRegistartor.class })
public class SnippetTest extends PowerMockTestCase{
#org.testng.annotations.Test
public void testRegisterService() throws Exception {
long expectedId = 42;
// We create a new instance of test class under test as usually.
ServiceRegistartor tested = new ServiceRegistartor();
// This is the way to tell PowerMock to mock all static methods of a
// given class
PowerMock.mockStatic(IdGenerator.class);
/*
* The static method call to IdGenerator.generateNewId() expectation.
* This is why we need PowerMock.
*/
EasyMock.expect(IdGenerator.generateNewId()).andReturn(expectedId).once();
// Note how we replay the class, not the instance!
PowerMock.replay(IdGenerator.class);
long actualId = tested.registerService(new Object());
// Note how we verify the class, not the instance!
PowerMock.verify(IdGenerator.class);
// Assert that the ID is correct
assertEquals(expectedId, actualId);
}
}
While using PowerMock for static mocking, there is a class level instrumentation happening to make your mocking work. PowerMockTestCase class has a code (method beforePowerMockTestClass()) to switch your regular class loader to powermock class loader which orchestrates mocking injection. Hence you need to extend this class for static mock to work.
You need to have the PowerMock class-loaders configured so that the static classes can be intercepted (defined using the #PrepareForTest annotation).
You don't have to extend from PowerMockTestCase. For most cases you can also configure TestNG with a PowerMockObjectFactory instead:
#PrepareForTest({ IdGenerator.class, ServiceRegistartor.class })
public class SnippetTest {
#ObjectFactory
public IObjectFactory objectFactory() {
return new PowerMockObjectFactory();
}
#org.testng.annotations.Test
public void testRegisterService() throws Exception {
...
}
}
First-timer here, apologies if I've missed anything.
I'm hoping to get around a call to a static method using Spock. Feedback would be great
With groovy mocks, I thought I'd be able to get past the static call but haven't found it.
For background, I'm in the process of retrofitting tests in legacy java. Refactoring is prohibited. I'm using spock-0.7 with groovy-1.8.
The call to the static method is chained with an instance call in this form:
public class ClassUnderTest{
public void methodUnderTest(Parameter param){
//everything else commented out
Thing someThing = ClassWithStatic.staticMethodThatReturnsAnInstance().instanceMethod(param);
}
}
staticMethod returns an instance of ClassWithStatic
instanceMethod returns the Thing needed in the rest of the method
If I directly exercise the global mock, it returns the mocked instance ok:
def exerciseTheStaticMock(){
given:
def globalMock = GroovyMock(ClassWithStatic,global: true)
def instanceMock = Mock(ClassWithStatic)
when:
println(ClassWithStatic.staticMethodThatReturnsAnInstance().instanceMethod(testParam))
then:
interaction{
1 * ClassWithStatic.staticMethodThatReturnsAnInstance() >> instanceMock
1 * instanceMock.instanceMethod(_) >> returnThing
}
}
But if I run the methodUnderTest from the ClassUnderTest:
def failingAttemptToGetPastStatic(){
given:
def globalMock = GroovyMock(ClassWithStatic,global: true)
def instanceMock = Mock(ClassWithStatic)
ClassUnderTest myClassUnderTest = new ClassUnderTest()
when:
myClassUnderTest.methodUnderTest(testParam)
then:
interaction{
1 * ClassWithStatic.staticMethodThatReturnsAnInstance() >> instanceMock
1 * instanceMock.instanceMethod(_) >> returnThing
}
}
It throws down a real instance of ClassWithStatic that goes on to fail in its instanceMethod.
Spock can only mock static methods implemented in Groovy. For mocking static methods implemented in Java, you'll need to use a tool like GroovyMock , PowerMock or JMockit.
PS: Given that these tools pull of some deep tricks in order to achieve their goals, I'd be interested to hear if and how well they work together with tests implemented in Groovy/Spock (rather than Java/JUnit).
Here is how I solved my similar issue (mocking a static method call which is being called from another static class) with Spock (v1.0) and PowerMock (v1.6.4)
import org.junit.Rule
import org.powermock.core.classloader.annotations.PowerMockIgnore
import org.powermock.core.classloader.annotations.PrepareForTest
import org.powermock.modules.junit4.rule.PowerMockRule
import spock.lang.Specification
import static org.powermock.api.mockito.PowerMockito.mockStatic
import static org.powermock.api.mockito.PowerMockito.when
#PrepareForTest([YourStaticClass.class])
#PowerMockIgnore(["javax.xml.*", "ch.qos.logback.*", "org.slf4j.*"])
class YourSpockSpec extends Specification {
#Rule
Powermocked powermocked = new Powermocked();
def "something something something something"() {
mockStatic(YourStaticClass.class)
when: 'something something'
def mocked = Mock(YourClass)
mocked.someMethod(_) >> "return me"
when(YourStaticClass.someStaticMethod(xyz)).thenReturn(mocked)
then: 'expect something'
YourStaticClass.someStaticMethod(xyz).someMethod(abc) == "return me"
}
}
The #PowerMockIgnore annotation is optional, only use it if there is some conflicts with existing libraries
A workaround would be to wrap the static method call into an instance method.
class BeingTested {
public void methodA() {
...
// was:
// OtherClass.staticMethod();
// replaced with:
wrapperMethod();
...
}
// add a wrapper method for testing purpose
void wrapperMethod() {
OtherClass.staticMethod();
}
}
Now you can use a Spy to mock out the static method.
class BeingTestedSpec extends Specification {
#Subject BeingTested object = new BeingTested()
def "test static method"() {
given: "a spy into the object"
def spyObject = Spy(object)
when: "methodA is called"
spyObject.methodA()
then: "the static method wrapper is called"
1 * spyObject.wrapperMethod() >> {}
}
}
You can also stub in canned response for the wrapper method if it's supposed to return a value. This solution uses only Spock built-in functions and works with both Java and Groovy classes without any dependencies on PowerMock or GroovyMock.
The way I've gotten around static methods in Groovy/Spock is by creating proxy classes that are substituted out in the actual code. These proxy classes simply return the static method that you need. You would just pass in the proxy classes to the constructor of the class you're testing.
Thus, when you write your tests, you'd reach out to the proxy class (that will then return the static method) and you should be able to test that way.
I have recently found 'spock.mockfree' package, it helps mocking final classes and static classes/methods.
It is quite simple as with this framework, in this case, you would need only to Spy() the class under test and #MockStatic the static method you need.
Example:
We used a static method returnA of StaticMethodClass class
public class StaticMethodClass {
public static String returnA() {
return "A";
}
}
here is the calling code
public class CallStaticMethodClass {
public String useStatic() {
return StaticMethodClass.returnA();
}
}
Now we need to test the useStatic method of CallStaticMethodClass class But spock itself does not support mock static methods, and we support
class CallStaticMethodClassTest extends Specification {
def 'call static method is mocked method'() {
given:
CallStaticMethodClass callStaticMethodClass = Spy()
println("useStatic")
expect:
callStaticMethodClass.useStatic() == 'M'
}
#MockStatic(StaticMethodClass)
public static String returnA() {
return "M";
}
}
We use the #MockStatic annotation to mark which class needs to be mocked
Directly implement the static method that requires mocking under it, the method signature remains the same, but the implementation is different.
Link to the framework:
https://github.com/sayweee/spock-mockfree/blob/498e09dc95f841c4061fa8224fcaccfc53904c67/README.md