It's useful to test exception handling. In this specific case, I have a extractor that will do a specific task when an exception is thrown while unmarshaling a specific class.
Example Code
Below is a simplified example of the code. The production version is much more complicated.
public class Example {
public static enum EntryType {
TYPE_1,
TYPE_2
}
public static class Thing {
List<String> data = new ArrayList<String>();
EnumSet<EntryType> failedConversions = EnumSet.noneOf(EntryType.class);
}
public static class MyHelper {
public String unmarshal(String input) throws UnmarshalException {
// pretend this does more complicated stuff
return input + " foo ";
}
}
public static class MyService {
MyHelper adapter = new MyHelper();
public Thing process() {
Thing processed = new Thing();
try {
adapter.unmarshal("Type 1");
} catch (UnmarshalException e) {
processed.failedConversions.add(EntryType.TYPE_1);
}
// do some stuff
try {
adapter.unmarshal("Type 2");
} catch (UnmarshalException e) {
processed.failedConversions.add(EntryType.TYPE_2);
}
return processed;
}
}
}
Things I've Tried
Here's a list of things I've tried. For brevity, I haven't filled in all the mundane details.
Spying
The following method doesn't do anything and the exception doesn't throw. I'm not sure why.
#Test
public void shouldFlagFailedConversionUsingSpy()
throws Exception {
MyHelper spied = spy(fixture.adapter);
doThrow(new UnmarshalException("foo")).when(spied).unmarshal(
Mockito.eq("Type 1"));
Thing actual = fixture.process();
assertEquals(1, actual.failedConversions.size());
assertThat(actual.failedConversions.contains(EntryType.TYPE_1), is(true));
}
Mocking
The following didn't work because partial mocks don't seem to play well with methods that throw exceptions.
#Test
public void shouldFlagFailedConversionUsingMocks()
throws Exception {
MyHelper mockAdapter = mock(MyHelper.class);
when(mockAdapter.unmarshal(Mockito.anyString())).thenCallRealMethod();
when(mockAdapter.unmarshal(Mockito.eq("Type 2"))).thenThrow(
new UnmarshalException("foo"));
Thing actual = fixture.process();
assertEquals(1, actual.failedConversions.size());
assertThat(actual.failedConversions.contains(EntryType.TYPE_2), is(true));
}
ThenAnswer
This works, but I'm not sure if it's the proper way to do this:
#Test
public void shouldFlagFailedConversionUsingThenAnswer() throws Exception {
final MyHelper realAdapter = new MyHelper();
MyHelper mockAdapter = mock(MyHelper.class);
fixture.adapter = mockAdapter;
when(mockAdapter.unmarshal(Mockito.anyString())).then(
new Answer<String>() {
#Override
public String answer(InvocationOnMock invocation)
throws Throwable {
Object[] args = invocation.getArguments();
String input = (String) args[0];
if (input.equals("Type 1")) {
throw new UnmarshalException("foo");
}
return realAdapter.unmarshal(input);
}
});
Thing actual = fixture.process();
assertEquals(1, actual.failedConversions.size());
assertThat(actual.failedConversions.contains(EntryType.TYPE_1), is(true));
}
Question
Although the thenAnswer method works, it doesn't seem to be the proper solution. What is the correct way to perform a partial mock for this situation?
I'm not quite sure what you were getting at with the mocking and the spying, but you only really need to mock here.
First, I ran into a few snags when trying your mocks out for whatever reason. I believe this had to do with the spy call which was messed up in some way. I did eventually overcome these, but I wanted to get something simple to pass.
Next, I did notice something off with the way you were spying (the basis of my approach):
MyHelper spied = spy(fixture.adapter);
This implies that you want an instance of MyHelper mocked out, not spied. The worst part is that even if this object were fully hydrated, it wouldn't be properly injected since you haven't reassigned it to the test object (which I presume is fixture).
My preference is to use the MockitoJUnitRunner to help with the injection of mocked instances, and from there I build up a basis of what it is I actually need to mock.
There's only one mocked instance and then the test object, and this declaration will ensure that they're both instantiated and injected:
#RunWith(MockitoJUnitRunner.class)
public class ExampleTest {
#Mock
private MyHelper adapter;
#InjectMocks
private MyService fixture;
}
The idea is that you're injecting your mock into the fixture. You don't have to use this - you could use standard setters in a #Before declaration, but I prefer this since it greatly reduces the boilerplate code you have to write to get mocking to work.
Now there's only one change to be made: remove the spy instance and replace its previous usage with the actual mock.
doThrow(new UnmarshalException("foo")).when(adapter).unmarshal(eq("Type 1"));
With all of the code hoisted, this passes:
#RunWith(MockitoJUnitRunner.class)
public class ExampleTest {
#Mock
private MyHelper adapter;
#InjectMocks
private MyService fixture;
#Test
public void shouldFlagFailedConversionUsingSpy()
throws Exception {
doThrow(new UnmarshalException("foo")).when(adapter).unmarshal(eq("Type 1"));
Thing actual = fixture.process();
assertEquals(1, actual.failedConversions.size());
assertThat(actual.failedConversions.contains(Example.EntryType.TYPE_1), is(true));
}
}
Not being one to want to leave the question/use case incomplete, I circled around and replaced the test with the inner classes, and it works fine too:
#RunWith(MockitoJUnitRunner.class)
public class ExampleTest {
#Mock
private Example.MyHelper adapter;
#InjectMocks
private Example.MyService fixture;
#Test
public void shouldFlagFailedConversionUsingSpy()
throws Exception {
doThrow(new UnmarshalException("foo")).when(adapter).unmarshal(eq("Type 1"));
Example.Thing actual = fixture.process();
assertEquals(1, actual.failedConversions.size());
assertThat(actual.failedConversions.contains(Example.EntryType.TYPE_1), is(true));
}
}
Related
I need to create a Junit test for a class in an AEM project and I'm having NullPointerException problems:
I create the ClassTestImpl
#ExtendWith({AemContextExtension.class, MockitoExtension.class})
class TestImpl {
private final AemContext ctx = new AemContext();
#Mock
private Test test;
#Mock
private ModelFactory modelFactory;
#BeforeEach
void setUp() throws Exception {
ctx.addModelsForClasses(TestImpl.class);
ctx.load().json("/com/project/core/models/adobe/TestImplTest.json","/content");
lenient().when(modelFactory.getModelFromWrappedRequest(eq(ctx.request()),
any(Resource.class), eq(Test.class)))
.thenReturn(test);
}
#Test
void testGetText() {
final String expected = "textTEST";
ctx.currentResource("/content/text");
Test test = ctx.request().adaptTo(Test.class);
String actual = test.getText();
assertEquals(expected,actual);
}
and the json structure:
"text": {
"jcr:primaryType": "nt:unstructured",
"sling:resourceType": "project/components/core/title",
"text": "textTEST"
}
}
when i Run test i give that result:
#Test
void testGetText() {
final String expected = "titleTEST";
ctx.currentResource("/content/title");
Title title = ctx.request().adaptTo(Title.class);
-->String actual = title[NullPointerException].getText();<--
assertEquals(expected,actual);
}
It looks like your model is a null reference. You do try to mock it with MockitoExtension but that's largely superfluous, given that you're also using AemContextExtension and it's probably the cause of the issue.
Null pointers aside, this code doesn't even test anything. Everything is mocked, even the Test class which I understand to be the subject under test.
Also, the parameter you're passing to addModelsForClasses looks like the test class (TestImpl) rather than the class of the Sling Model Test.
Instead of relying on Mockito, let the AEM Mocks library set up all the underlying objects by itself and make sure the class you're testing is the real thing, rather than a mock.
#ExtendWith(AemContextExtension.class)
class TestImpl {
private final AemContext ctx = new AemContext();
#BeforeEach
void setUp() throws Exception {
ctx.addModelsForClasses(Test.class); // Give it the Sling Model
ctx.load().json("/com/project/core/models/adobe/TestImplTest.json","/content");
}
#Test
void testGetText() {
final String expected = "textTEST";
ctx.currentResource("/content/text");
Test test = ctx.request().adaptTo(Test.class); // It'll use the actual class, not a mock this way
String actual = test.getText();
assertEquals(expected,actual);
}
}
See
https://sling.apache.org/documentation/development/sling-mock.html#sling-models-1
https://wcm.io/testing/aem-mock/usage-content-loader-builder.html
In application code when dealing with forms it is recommended to use a FormFactory to create a Form wrapper around the form of type T. But when it comes to testing, what is the way to create a Form? (Do you have to inject FormFactory in the test?)
My app does something similar to that:
class MyAmazingClass {
private final FormFactory formFactory;
#Inject
MyAmazingClass(FormFactory formFactory) {
this.formFactory = formFactory;
}
public CompletionStage<Result> myAmazingMethodHandlingForms() {
Form<String> form = formFactory.form(String.class).bindFromRequest();
// ... Actually doing something
return null;
}
}
What shall my test class (for unit testing) looks like?
I am trying something like this but I think I should not try to inject the FormFactory (also it does not seems to work):
public class MyAmazingClassTest extends WithApplication {
#Mock
FormFactory mockedFormFactory;
#Inject
FormFactory realFormFactory;
MyAmazingClass myAmazingClass;
#Override
protected Application provideApplication() {
return new GuiceApplicationBuilder().build();
}
#Before
public void setUp() throws Exception {
myAmazingClass = new MyAmazingClass(mockedFormFactory);
}
#Test
public void testMyAmazingMethodHandlingForms() throws Exception {
String myString = "ciao";
Form<String> stringForm = realFormFactory.form(String.class).fill(myString);
when(mockedFormFactory.form(eq(String.class)).bindFromRequest()).thenReturn(stringForm);
myAmazingClass.myAmazingMethodHandlingForms();
// Some assertions...
}
}
I am using JUnit 4, Java 8 and Play framework 2.5.
I would say that mixing mocks with the real application is not the best idea here. You should either use mocks (and avoid WithApplication), or you can use the "real" instances by calling app.injector().instanceOf() (including for your MyAmazingClass). For example, when only using mocks:
public class MyAmazingClassTest {
#Test
public void testMyAmazingMethodHandlingForms() throws Exception {
Form<String> form = mock(Form.class);
// setup the mocked form as you expect it to behave
FormFactory formFactory = mock(FormFactory.class);
when(formFactory.form(eq(String.class)).bindFromRequest()).thenReturn(form);
MyAmazingClass myAmazingClass = new MyAmazingClass(formFactory);
myAmazingClass.myAmazingMethodHandlingForms();
// Some assertions...
}
}
Testing using the real instances would requires you to do a request, since apparently, you are binding from the request:
public class MyAmazingClassTest extends WithApplication {
#Test
public void testMyAmazingMethodHandlingForms() throws Exception {
Map<String, String> formData = new HashMap<>();
formData.put("some", "value");
// fill the form with the test data
Http.RequestBuilder fakeRequest = Helpers.fakeRequest().bodyForm(formData).method(Helpers.POST);
Result result = Helpers.route(app, fakeRequest);
// make assertions over the result or something else.
}
}
I am writing unit test case for a Class
public class CurrentMoreInfoDataProvider implements CurrentMoreInfoInterface.presenterToModel{
private CurrentMoreInfoInterface.modelToPresenter modelToPresenter;
public CurrentMoreInfoDataProvider(CurrentMoreInfoInterface.modelToPresenter modelToPresenter) {
this.modelToPresenter = modelToPresenter;
}
#Override
public void provideData() {
WeatherApiResponsePojo apiWeatherData = WeatherDataSingleton.getInstance().getApiWeatherData();
if(null != apiWeatherData.getCurrently()){
CurrentlyPojo currently = apiWeatherData.getCurrently();
if(null != currently){
populateWeatherData(currently);
}
}
}
public void populateWeatherData(CurrentlyPojo currently) {....}
I want to just use verify method of power mock to test whether populateWeatherData get executed or not. Below is my test case so far.
#RunWith(PowerMockRunner.class)
#PrepareForTest(CurrentMoreInfoDataProvider.class)
public class TestCurrentMoreInfoDataProvider {
private CurrentMoreInfoDataProvider dataProvider;
#Mock
CurrentMoreInfoInterface.modelToPresenter modelToPresenter;
private CurrentlyPojo currentlyPojo = new CurrentlyPojo();
#Test
public void testPopulateWeatherData(){
dataProvider = PowerMockito.spy(new CurrentMoreInfoDataProvider(modelToPresenter));
dataProvider.provideData();
Mockito.verify(dataProvider).populateWeatherData(currentlyPojo);
}
}
If I run this I get null pointer exception in provideData method at
if(null != apiWeatherData.getCurrently()){
How should I provide apiWeatherData to provideData method in that class?
You have to mock WeatherDataSingleton.getInstance().getApiWeatherData() too.
This would be much easier if you would not use static access in general and the Singelton pattern in particular.
I tried mocking it, but how should i provide that mock object to provideData() ?
create a mock of WeatherDataSingleton.
Configure your Test so that this mock is used (by properly using dependency injection or by surrendering to your bad design using Powermock).
configure the mock to return the data:
doReturn(currentlyPojo).when(weatherDataSingletonMock).getApiWeatherData();
This resolves the NPE.
I dont think you need to go for PowerMockito if you apply a simple refactor to your production code:
public class CurrentMoreInfoDataProvider{
#Override
public void provideData() {
WeatherApiResponsePojo apiWeatherData = getApiWeatherData();
if(null != apiWeatherData.getCurrently()){
CurrentlyPojo currently = apiWeatherData.getCurrently();
if(null != currently){
populateWeatherData(currently);
}
}
}
WeatherApiResponsePojo getApiWeatherData(){
return WeatherDataSingleton.getInstance().getApiWeatherData();
}
then in your test expect that new method to return certain object:
#RunWith(MockitoJUnitRunner.class)
public class TestCurrentMoreInfoDataProvider {
private CurrentMoreInfoDataProvider dataProvider;
#Mock
CurrentMoreInfoInterface.modelToPresenter modelToPresenter;
#Mock
WeatherApiResponsePojo apiWeatherDataMock;
private CurrentlyPojo currentlyPojo = new CurrentlyPojo();
#Test
public void testPopulateWeatherData(){
dataProvider = PowerMockito.spy(new CurrentMoreInfoDataProvider(modelToPresenter));
doReturn(apiWeatherDataMock).when(dataProvider).getApiWeatherData();
dataProvider.provideData();
Mockito.verify(dataProvider).populateWeatherData(currentlyPojo);
}
}
I have a parent workflow (ParentWorkflow) calling a child workflow (ChildWorkflow) and I'm trying to test out the call.
The parent code looks something like this:
public class ParentWorkflow {
private final ChildWorkflowClientFactory childWorkflowClientFactory =
new ChildWorkflowClientFactoryImpl();
public void runWorkflow() {
new TryCatch() {
#Override
protected void doTry() throws Throwable {
Promise<Void> workflowFinished = childWorkflowClient.childWorkflow(x);
...
}
...
}
}
I want to mock out the
childWorkflowClient.childWorkflow(x)
call, however when I am hooking up the unit test I don't appear to have the option to inject the client factory, the unit test code looks like this:
#Rule
public WorkflowTest workflowTest = new WorkflowTest();
#Mock
private Activities mockActivities;
private ParentWorkflowClientFactory workflowFactory
= new ParentWorkflowClientFactoryImpl();
#Before
public void setUp() throws Exception {
// set up mocks
initMocks(this);
workflowTest.addActivitiesImplementation(mockActivities);
workflowTest.addWorkflowImplementationType(ParentWorkflowImpl.class);
workflowTest.addWorkflowImplementationType(ChildWorkflowImpl.class);
I don't appear to be able to pass anything into the workflow implementation classes, is there another way I can mock the child workflow out?
You can test workflow code directly mocking its dependencies without using workflowTest:
/**
* Rule is still needed to initialize asynchronous framework.
*/
#Rule
public WorkflowTest workflowTest = new WorkflowTest();
#Mock
private ActivitiesClient mockActivities;
#Mock
private BWorkflowClientFactory workflowFactory;
#Before
public void setUp() throws Exception {
// set up mocks
initMocks(this);
}
#Test
public void myTest() {
AWorkflowImpl w = new AWorkflowImpl(workflowFactory);
w.execute(); // whatever execute method of the workflow
}
This approach allows testing parts of the workflow encapsulated in other objects instead of the entire workflow.
If for whatever reason (for example you are using other testing framework than JUnit) you don't want to rely on WorkflowTest #Rule asynchronous code can be always executed using AsyncScope:
#Test
public void asyncTest() {
AsyncScope scope = new AsyncScope() {
protected void doAsync() {
// Any asynchronous code
AWorkflowImpl w = new AWorkflowImpl(workflowFactory);
w.execute(); // whatever execute method of the workflow
}
};
scope.eventLoop();
}
EDIT: The below only applies to SpringWorkflowTest; WorkflowTest doesn't have addWorkflowImplementation for some reason.
The correct way to use the WorkflowTest would be to add a mock implementation for the child workflow rather than adding the actual type:
#Rule
public SpringWorkflowTest workflowTest = new SpringWorkflowTest();
#Mock
private Activities mockActivities;
#Mock
private ChildWorkflow childWorkflowMock;
private ParentWorkflowClientFactory workflowFactory
= new ParentWorkflowClientFactoryImpl();
#Before
public void setUp() throws Exception {
// set up mocks
initMocks(this);
workflowTest.addActivitiesImplementation(mockActivities);
workflowTest.addWorkflowImplementationType(ParentWorkflowImpl.class);
workflowTest.addWorkflowImplementation(childWorkflowMock);
...
}
The framework will then call this mock instead of the actual implementation when you use the factory.
Suppose that I have a class like;
public class FooBar {
public int getMethod(List<String> code){
if(code.size() > 100)
throw new Exception;
return 0;
}
}
and I have a test class like this;
#RunWith(PowerMockRunner.class)
#PrepareForTest(FooBar.class)
public class FooBarTest{
FooBar fooBarInstance;
#Before
public void setUp() {
//MockitoAnnotations.initMocks(this);
fooBarInstance = new FooBar();
}
#Test(expected = Exception.class)
public void testGetCorrelationListCodesParameter() {
List<String> codes = Mockito.spy(new ArrayList<String>());
Mockito.doReturn(150).when(codes).size();
fooBarInstance.getMethod(codes);
}
}
How can I make this test method to throw an exception ? I've dealing for hours to do this. Well thanks anyway.
Spying is not needed, mocking is enough. As #David said, also mocking is not needed and not recommended for value object.
Using #Test(expected = Exception.class) has many drawbacks, test can pass when exception is thrown from not expected places. Test is not working but is visible as green.
I prefer BDD style testing with catch-exception.
Reasons for using catch-exceptions
(...) in comparison to the use of try/catch blocks.
The test is more concise and easier to read.
The test cannot be corrupted by a missing assertion. Assume you forgot to type fail() behind the method call that is expected to throw an exception.
(...) in comparison to test runner-specific mechanisms that catch and verify exceptions.
A single test can verify more than one thrown exception.
The test can verify the properties of the thrown exception after the exception is caught.
The test can specify by which method call the exception must be thrown.
The test does not depend on a specific test runner (JUnit4, TestNG).
import static com.googlecode.catchexception.CatchException.caughtException;
import static com.googlecode.catchexception.apis.CatchExceptionAssertJ.*;
public class FooBarTest {
FooBar sut = new FooBar(); // System Under Test
#Test
public void shouldThrowExceptionWhenListHasTooManyElements() {
when(sut).getMethod(listWithSize(150));
then(caughtException()).isInstanceOf(Exception.class);
}
private List<String> listWithSize(int size) {
return new ArrayList<String>(Arrays.asList(new String[size]));
}
}
Full working code for this test: https://gist.github.com/mariuszs/8543918
Not recommended solution with expected and mocking.
#RunWith(MockitoJUnitRunner.class)
public class FooBarTest {
#Mock
List<String> codes;
FooBar fooBarInstance = new FooBar();
#Test(expected = Exception.class)
public void shouldThrowExceptionWhenListHasTooManyElements() throws Exception {
when(codes.size()).thenReturn(150);
fooBarInstance.getMethod(codes);
}
}
A list is a value object. It's not something we should mock. You can write this whole test without mocking anything, if you're prepared to build a list that has a size in excess of 100.
Also, I prefer to use JUnit's ExpectedException mechanism, because it lets you check which line of the test method threw the exception. This is better than passing an argument to the #Test annotation, which only lets you check that the exception was thrown somewhere within the method.
public class FooBarTest {
#Rule
public ExpectedException exceptionRule = ExpectedException.none();
private FooBar toTest = new FooBar();
#Test
public void getMethodThrowsException_whenListHasTooManyElements() {
List<String> listWith101Elements =
new ArrayList<String>(Arrays.asList(new String[101]));
exceptionRule.expect(Exception.class);
toTest.getMethod(listWith101Elements);
}
}