I have this TestNG test method code:
#InjectMocks
private FilmeService filmeService = new FilmeServiceImpl();
#Mock
private FilmeDAO filmeDao;
#BeforeMethod(alwaysRun=true)
public void injectDao() {
MockitoAnnotations.initMocks(this);
}
//... another tests here
#Test
public void getRandomEnqueteFilmes() {
#SuppressWarnings("unchecked")
List<Filme> listaFilmes = mock(List.class);
when(listaFilmes.get(anyInt())).thenReturn(any(Filme.class));
when(filmeDao.listAll()).thenReturn(listaFilmes);
List<Filme> filmes = filmeService.getRandomEnqueteFilmes();
assertNotNull(filmes, "Lista de filmes retornou vazia");
assertEquals(filmes.size(), 2, "Lista não retornou com 2 filmes");
}
And I'm getting a "org.mockito.exceptions.misusing.InvalidUseOfMatchersException:
Invalid use of argument matchers!
0 matchers expected, 1 recorded:" in the call of listAll() method in this code:
#Override
public List<Filme> getRandomEnqueteFilmes() {
int indice1, indice2 = 0;
List<Filme> filmesExibir = new ArrayList<Filme>();
List<Filme> filmes = dao.listAll();
Random randomGenerator = new Random();
indice1 = randomGenerator.nextInt(5);
do {
indice2 = randomGenerator.nextInt(5);
} while(indice1 == indice2);
filmesExibir.add(filmes.get(indice1));
filmesExibir.add(filmes.get(indice2));
return filmesExibir;
}
I'm prety sure I'm missing something here but I don't know what it is! Someone help?
when(listaFilmes.get(anyInt())).thenReturn(any(Filme.class));
There's your problem. You can't use any in a return value. any is a Matcher—it's used to match parameter values for stubbing and verification—and doesn't make sense in defining a return value for a call. You'll need to explicitly return a Filme instance, or leave it null (which is the default behavior, which would defeat the point of stubbing).
I should note that it's often a good idea to use a real List instead of a mock List. Unlike custom code you've developed, List implementations are well-defined and well-tested, and unlike mock Lists a real List is very unlikely to break if you refactor your system under test to call different methods. It's a matter of style and testing philosophy, but you may find it advantageous just to use a real List here.
Why would the above rule cause that exception? Well, this explanation breaks some of Mockito's abstractions, but matchers don't behave like you think they might—they record a value onto a secret ThreadLocal stack of ArgumentMatcher objects and return null or some other dummy value, and in the call to when or verify Mockito sees a non-empty stack and knows to use those Matchers in preference to actual argument values. As far as Mockito and the Java evaluation order are concerned, your code looks like the following:
when(listaFilmes.get(anyInt())).thenReturn(null);
when(filmeDao.listAll(any())).thenReturn(listaFilmes); // nonsense
Naturally Mockito sees an any matcher, and listAll doesn't take an argument, so there are 0 matchers expected, 1 recorded.
Related
I am not able to understand why below two tests are not giving the same result.
#Service
public class SomeManager{
private final SomeDependency someDependency;
#Autowired
public SomeManager(SomeDependency someDependency){
this.someDependency = someDependency;
}
public List<returnType> methodToTest(Arg arg){
List<JsonObject> jo = someDependency.search(arg);
return jo.stream().map(returnType::parse).collect(Collectors.toList());
}
}
Test with any(). This Test pass.
#RunWith(SpringJUnit4ClassRunner.class)
public class TestMethodToTest(){
#Test
public void TestMethod(){
SomeDependency someDependency = mock(SomeDependency.class);
List<JsonObject> expected := \some valid list of JsonObject\
// Here I used any() method.
when(someDependency.search(any())).thenReturn(expected);
SomeManager someManager = new SomeManager(someDependency);
List<returnType> actual = someManager.methodToTest(any(Arg.class));
assertArrayEquals(acutal.toArray(), expected.stream().map(returnType::parse).toArray());
}
}
But since search(Arg arg) method of SomeDependency takes parameter of class Arg so I changed above test like this:
#RunWith(SpringJUnit4ClassRunner.class)
public class TestMethodToTest(){
#Test
public void TestMethod(){
SomeDependency someDependency = mock(SomeDependency.class);
List<JsonObject> expected := \some valid list of JsonObject\
// Here I used any(Arg.class) method.
when(someDependency.search(any(Arg.class))).thenReturn(expected);
SomeManager someManager = new SomeManager(someDependency);
List<returnType> actual = someManager.methodToTest(any(Arg.class));
assertArrayEquals(acutal.toArray(), expected.stream().map(returnType::parse).toArray());
}
}
This second test fails with output java.lang.AssertionError: array lengths differed, expected.length=1 actual.length=0.What's the possible reason behind this?
Note: The value expected.length=1 in output depends on what value is provided by the user as valid list of json objects in the test.
The difference stems from the fact that any matches null, while anyClass does not match null. See ArgumentMatchers javadoc:
any() Matches anything, including nulls and varargs.
any(Class<T> type) Matches any object of given type, excluding nulls.
You are passing null to your method under test here:
List<returnType> actual = someManager.methodToTest(any(Arg.class));
any() returns null which you pass to method under test.
Note that using argument matchers this way is illegal - you should only call them inside calls to when and verify. You should pass a real instance of Arg to method under test.
See Mockito javadoc
Matcher methods like any(), eq() do not return matchers. Internally, they record a matcher on a stack and return a dummy value (usually null). This implementation is due to static type safety imposed by the java compiler. The consequence is that you cannot use any(), eq() methods outside of verified/stubbed method.
I'm using Mockito 1.9.0. I want mock the behaviour for a single method of a class in a JUnit test, so I have
final MyClass myClassSpy = Mockito.spy(myInstance);
Mockito.when(myClassSpy.method1()).thenReturn(myResults);
The problem is, in the second line, myClassSpy.method1() is actually getting called, resulting in an exception. The only reason I'm using mocks is so that later, whenever myClassSpy.method1() is called, the real method won't be called and the myResults object will be returned.
MyClass is an interface and myInstance is an implementation of that, if that matters.
What do I need to do to correct this spying behaviour?
Let me quote the official documentation:
Important gotcha on spying real objects!
Sometimes it's impossible to use when(Object) for stubbing spies. Example:
List list = new LinkedList();
List spy = spy(list);
// Impossible: real method is called so spy.get(0) throws IndexOutOfBoundsException (the list is yet empty)
when(spy.get(0)).thenReturn("foo");
// You have to use doReturn() for stubbing
doReturn("foo").when(spy).get(0);
In your case it goes something like:
doReturn(resultsIWant).when(myClassSpy).method1();
In my case, using Mockito 2.0, I had to change all the any() parameters to nullable() in order to stub the real call.
My case was different from the accepted answer. I was trying to mock a package-private method for an instance that did not live in that package
package common;
public class Animal {
void packageProtected();
}
package instances;
class Dog extends Animal { }
and the test classes
package common;
public abstract class AnimalTest<T extends Animal> {
#Before
setup(){
doNothing().when(getInstance()).packageProtected();
}
abstract T getInstance();
}
package instances;
class DogTest extends AnimalTest<Dog> {
Dog getInstance(){
return spy(new Dog());
}
#Test
public void myTest(){}
}
The compilation is correct, but when it tries to setup the test, it invokes the real method instead.
Declaring the method protected or public fixes the issue, tho it's not a clean solution.
The answer by Tomasz Nurkiewicz appears not to tell the whole story!
NB Mockito version: 1.10.19.
I am very much a Mockito newb, so can't explain the following behaviour: if there's an expert out there who can improve this answer, please feel free.
The method in question here, getContentStringValue, is NOT final and NOT static.
This line does call the original method getContentStringValue:
doReturn( "dummy" ).when( im ).getContentStringValue( anyInt(), isA( ScoreDoc.class ));
This line does not call the original method getContentStringValue:
doReturn( "dummy" ).when( im ).getContentStringValue( anyInt(), any( ScoreDoc.class ));
For reasons which I can't answer, using isA() causes the intended (?) "do not call method" behaviour of doReturn to fail.
Let's look at the method signatures involved here: they are both static methods of Matchers. Both are said by the Javadoc to return null, which is a little difficult to get your head around in itself. Presumably the Class object passed as the parameter is examined but the result either never calculated or discarded. Given that null can stand for any class and that you are hoping for the mocked method not to be called, couldn't the signatures of isA( ... ) and any( ... ) just return null rather than a generic parameter* <T>?
Anyway:
public static <T> T isA(java.lang.Class<T> clazz)
public static <T> T any(java.lang.Class<T> clazz)
The API documentation does not give any clue about this. It also seems to say the need for such "do not call method" behaviour is "very rare". Personally I use this technique all the time: typically I find that mocking involves a few lines which "set the scene" ... followed by calling a method which then "plays out" the scene in the mock context which you have staged... and while you are setting up the scenery and the props the last thing you want is for the actors to enter stage left and start acting their hearts out...
But this is way beyond my pay grade... I invite explanations from any passing Mockito high priests...
* is "generic parameter" the right term?
One more possible scenario which may causing issues with spies is when you're testing spring beans (with spring test framework) or some other framework that is proxing your objects during test.
Example
#Autowired
private MonitoringDocumentsRepository repository
void test(){
repository = Mockito.spy(repository)
Mockito.doReturn(docs1, docs2)
.when(repository).findMonitoringDocuments(Mockito.nullable(MonitoringDocumentSearchRequest.class));
}
In above code both Spring and Mockito will try to proxy your MonitoringDocumentsRepository object, but Spring will be first, which will cause real call of findMonitoringDocuments method. If we debug our code just after putting a spy on repository object it will look like this inside debugger:
repository = MonitoringDocumentsRepository$$EnhancerBySpringCGLIB$$MockitoMock$
#SpyBean to the rescue
If instead #Autowired annotation we use #SpyBean annotation, we will solve above problem, the SpyBean annotation will also inject repository object but it will be firstly proxied by Mockito and will look like this inside debugger
repository = MonitoringDocumentsRepository$$MockitoMock$$EnhancerBySpringCGLIB$
and here is the code:
#SpyBean
private MonitoringDocumentsRepository repository
void test(){
Mockito.doReturn(docs1, docs2)
.when(repository).findMonitoringDocuments(Mockito.nullable(MonitoringDocumentSearchRequest.class));
}
Important gotcha on spying real objects
When stubbing a method using spies , please use doReturn() family of methods.
when(Object) would result in calling the actual method that can throw exceptions.
List spy = spy(new LinkedList());
//Incorrect , spy.get() will throw IndexOutOfBoundsException
when(spy.get(0)).thenReturn("foo");
//You have to use doReturn() for stubbing
doReturn("foo").when(spy).get(0);
I've found yet another reason for spy to call the original method.
Someone had the idea to mock a final class, and found about MockMaker:
As this works differently to our current mechanism and this one has different limitations and as we want to gather experience and user feedback, this feature had to be explicitly activated to be available ; it can be done via the mockito extension mechanism by creating the file src/test/resources/mockito-extensions/org.mockito.plugins.MockMaker containing a single line: mock-maker-inline
Source: https://github.com/mockito/mockito/wiki/What%27s-new-in-Mockito-2#mock-the-unmockable-opt-in-mocking-of-final-classesmethods
After I merged and brought that file to my machine, my tests failed.
I just had to remove the line (or the file), and spy() worked.
One way to make sure a method from a class is not called is to override the method with a dummy.
WebFormCreatorActivity activity = spy(new WebFormCreatorActivity(clientFactory) {//spy(new WebFormCreatorActivity(clientFactory));
#Override
public void select(TreeItem i) {
log.debug("SELECT");
};
});
As mentioned in some of the comments, my method was "static" (though being called on by an instance of the class)
public class A {
static void myMethod() {...}
}
A instance = spy(new A());
verify(instance).myMethod(); // still calls the original method because it's static
Work around was make an instance method or upgrade Mockito to a newer version with some config: https://stackoverflow.com/a/62860455/32453
Bit late to the party but above solutions did not work for me , so sharing my 0.02$
Mokcito version: 1.10.19
MyClass.java
private int handleAction(List<String> argList, String action)
Test.java
MyClass spy = PowerMockito.spy(new MyClass());
Following did NOT work for me (actual method was being called):
1.
doReturn(0).when(spy , "handleAction", ListUtils.EMPTY_LIST, new String());
2.
doReturn(0).when(spy , "handleAction", any(), anyString());
3.
doReturn(0).when(spy , "handleAction", null, null);
Following WORKED:
doReturn(0).when(spy , "handleAction", any(List.class), anyString());
I would like to ask for a help and suggestions what is a correct approach in my case (probably its easy but I'm just starting with JUnit). Here is a part of my code
public boolean arrayListEmpty()
{
if(numericalSequence.isEmpty() == true)
return true;
else
return false;
}
This is a public method from model which I suppose i should test, it's just returning true if my numericalsequence is empty as you can see. I cant check it directly invoking numericalSequence.isEmpty (in controller where I need it) because it is private.
So obvious thing is to check
assertEquals(true, test.arrayListEmpty());
So my question is about suggestions what other asserts should I use/what cases should I predict which can come out. Should I in Test method fill numericalSequence with some values and assert it also? (for me its not necessary because any value inserted into sequence = not null but maybe it is not so easy)
First of all, welcome to Stack Overflow!
Looking at your question, it sounds like you're new to unit-testing (correct me if I'm wrong). So, I'll break my answers in to two sections; (1) answering your question, and (2) to give a general direction of how to write good tests and testable classes.
1. Answering your question
There are a couple more use cases you can think of here:
What happens if numericalSequence is null?
What if numericalSequence has 1 element?
What if numericalSequence has a null element?
Some of the cases above may not be possible depending on how your class is set up, but it's a test worth having so that any changes to the class that violates the "previously agreed behavior" of one of these test cases would fail.
2. Writing good tests
There are no strict guidelines on what to do in order to write good tests, however, if you structure your code to be testable, you'll find that writing good tests becomes easier, and would be less of chore. Allow me to explain.
NOTE: This is not a comprehensive guide, but is meant to start your journey in to the path of how to write better code, and better tests
So assume a class that needs to be tested is written like this:
class MyClass {
// NOTE: This is not `final`
private List<Integer> numericalSequence;
public MyClass() {
this.numericalSequence = new ArrayList<>();
}
public void doSomething(Integer x) {
if (x < 0) {
numericalSequence = new ArrayList<>();
} else {
numericalSequence.add(2 * x);
}
}
public boolean arrayListEmpty() {
// NOTE: Your sample code can be reduced to this one-liner
return numericalSequence.isEmpty();
}
}
Here are some of the flaws in the above code:
doSomething method allows nullable (boxed integer) values and so can cause NullPointerException in the first if statement.
The numericalSequence member is not final and hence the code that sets it to null is valid inside the doSomething method
The arrayListIsEmpty method does not check if numericalSequence is null
If I want to test how arrayListIsEmpty behaves when numericalSequence is null, or has null elements, it is hard to do so, unless you know how to get the class to that state.
If the class was re-written to the following:
class MyClass {
private final List<Integer> numericalSequence;
public MyClass() {
this(new ArrayList<>());
}
// Should be made public only if the classes that use this one needs to
// initialize this instance with the sequence. Make this package-private
// otherwise.
public MyClass(List<Integer> sequence) {
this.numericalSequence = sequence;
}
public void doSomething(int x) {
if (x < 0) {
// COMPILE ERROR: Cannot assign to a final member
// numericalSequence = new ArrayList<>();
numericalSequence.clear();
} else {
numericalSequence.add(2 * x);
}
}
public boolean arrayListEmpty() {
return numericalSequence == null || numericalSequence.isEmpty();
}
}
A few things to note about the above structure:
There are two constructors; the default invokes the one that takes a list of integers as the sequence, so that it reuses any logic that both would need to share. There are no logic in this example, but hopefully you'll come across one soon.
The doSomething() method doesn't accept Integer value, but int value that makes sure that x is never null (Java numerical primitive types cannot be null). This also means, numericalSequence cannot contain null values through doSomething().
Since numericalSequence can be initialized from outside of this class, the arrayListEmpty() method makes sure to check that numericalSequence is either null is truly empty.
Now you can write test cases like so:
#Test
public void arrayListEmpty_WhenListIsNull() {
MyClass test = MyClass(null);
assertTrue(test.arrayListEmpty());
}
#Test
public void arrayListEmpty_WhenListIsEmpty() {
MyClass test = MyClass();
assertTrue(test.arrayListEmpty());
}
#Test
public void arrayListEmpty_WhenListHasOnlyOneNonNullElement() {
List<Integer> sequence = new ArrayList<>();
sequence.add(0);
MyClass test = new MyClass(sequence);
assertFalse(test.arrayListEmpty());
}
#Test
public void arrayListEmpty_WhenListHasOnlyOneNullElement() {
List<Integer> sequence = new ArrayList<>();
sequence.add(null);
MyClass test = new MyClass(sequence);
assertFalse(test.arrayListEmpty());
}
Since doSomething() adds/clears the sequence, when writing tests for doSomething() make sure the call and verify the state of the class by checking the return value of arrayListEmpty().
For example:
#Test
public void doSomething_WhenInputLessThanZero() {
List<Integer> sequence = new ArrayList<>();
sequence.add(0);
MyClass test = new MyClass(sequence);
test.doSomething(-1);
assertTrue(test.arrayListEmpty());
}
My intention was to show a couple of things:
Structure your tests cases to be small and concise
Design your class to be easily testable
Hope this helps.
I'm using a Calendar object to determine whether or not to increase the workload of a system based on current day/hour values. Given that this object uses static methods, I'm using PowerMock to mock the static methods with the following annotations:
#RunWith(PowerMockRunner.class)
#PrepareForTest({ Calendar.class })
The code under test is pretty simple (though my logic needs work, I know):
public void determineDefaultMaximumScans() throws ParseException{
parseTime();
Calendar cal = Calendar.getInstance();
int dayOfWeek = cal.get(Calendar.DAY_OF_WEEK);
System.out.println(cal.get(Calendar.DAY_OF_WEEK));
if(dayOfWeek == (Calendar.SATURDAY) || dayOfWeek == (Calendar.SUNDAY)){
setDefaultMax(calculateNewDefaultMax(getDefaultMax()));
System.out.println("defaultMax increased by 20%");
} else {
if(currentTime.after(afterHoursBegin) && currentTime.before(afterHoursEnd)){
System.out.println("Not afterhours. Maintaining current maximum.");
setDefaultMax(defaultMax);
System.out.println("Current Maximum number of scans: " + getDefaultMax());
}
}
}
My test case reads as follows:
#SuppressWarnings("static-access")
#Test
public void testDetermineMaximumScans() throws ParseException{
PowerMock.mockStatic(Calendar.class);
String beginningTime = "18:00";
String endingTime = "05:00";
mockAfterHoursBegin = parser.parse(beginningTime);
mockAfterHoursEnd = parser.parse(endingTime);
mockCurrentTime = parser.parse(parser.format(new Date()));
EasyMock.expect(Calendar.getInstance()).andReturn(mockCalendar);
EasyMock.expect(mockCalendar.get(Calendar.DAY_OF_WEEK)).andReturn(6);
EasyMock.replay(mocks);
offHourMaximumCalculator.determineDefaultMaximumScans();
EasyMock.verify(mocks);
}
As of now, all of my attempts to return a specific value result in the following assertion error. Now I vaguely understand why it's returning the default but I do not see why I can't force the value or how to get around this expectation. Mocks in general are still a frustrating mystery to me. What am I missing?
java.lang.AssertionError:
Expectation failure on verify:
Calendar.get(7): expected: 1, actual: 0
Mocks are fairly simple. But wanting to mock static methods is a big running after complexity. I generally do not recommend to mock something like a Calendar. If you do weird and complex thing with it, just encapsulate in something you can test and mock easily.
And in fact, we pretty much never use Calendar.getInstance(). It returns something according to the locale. But it's rare that you don't want a specific calendar i.e. GregorianCalendar. So just do new GregorianCalendar.
But anyway, add a protected method doing
protected Calendar newCalendar() {
return Calendar.getInstance(); // or new GregorianCalendar()
}
will take 2 minutes and then a simple partial mock will do the trick.
Finally, I also don't recommend to use Calendar. You have a much nicer API in java.util.date in Java 8.
All this said, here is how you should do it. Calendar is a system class, so you need to follow a real specific path which is explained here.
#RunWith(PowerMockRunner.class)
#PrepareForTest(Calendar.class)
public class MyTest {
#Test
public void testDetermineMaximumScans() throws ParseException {
PowerMock.mockStatic(Calendar.class);
Calendar calendar = mock(Calendar.class);
EasyMock.expect(Calendar.getInstance()).andReturn(calendar);
EasyMock.expect(calendar.get(Calendar.DAY_OF_WEEK)).andReturn(6);
// really important to replayAll to replay the static expectation
PowerMock.replayAll(calendar);
assertThat(Calendar.getInstance().get(Calendar.DAY_OF_WEEK)).isEqualTo(6);
// and verifyAll is you want to verify that the static call actually happened
PowerMock.verifyAll();
}
}
what is the absolute minimal mocking that must be done to pass this test?
code:
class PrivateStaticFinal {
private static final Integer variable = 0;
public static Integer method() { return variable + 1; }
}
test:
#RunWith(PowerMockRunner.class)
#PrepareForTest(PrivateStaticFinal.class)
class PrivateStaticFinalTest {
#Test
public void testMethod() {
//TODO PrivateStaticFinal.variable = 100
assertEquals(PrivateStaticFinal.method(), 101);
}
}
related: Mock private static final variables in the testing class (no clear answer)
Disclaimer: After a lot of hunting around on various threads I have found an answer. It can be done, but the general concensus is that it is not very safe but seeing as how you are doing this ONLY IN UNIT TESTS, I think you accept those risks :)
The answer is not Mocking, since most Mocking does not allow you to hack into a final. The answer is a little more "hacky", where you are actually modifying the private field when Java is calling is core java.lang.reflect.Field and java.lang.reflect.Modifier classes (reflection). Looking at this answer I was able to piece together the rest of your test, without the need for mocking that solves your problem.
The problem with that answer is I was running into NoSuchFieldException when trying to modify the variable. The help for that lay in another post on how to access a field that was private and not public.
Reflection/Field Manipulation Explained:
Since Mocking cannot handle final, instead what we end up doing is hacking into the root of the field itself. When we use the Field manipulations (reflection), we are looking for the specific variable inside of a class/object. Once Java finds it we get the "modifiers" of it, which tell the variable what restrictions/rules it has like final, static, private, public, etc. We find the right variable, and then tell the code that it is accessible which allows us to change these modifiers. Once we have changed the "access" at the root to allow us to manipulate it, we are toggling off the "final" part of it. We then can change the value and set it to whatever we need.
To put it simply, we are modifying the variable to allow us to change its properties, removing the propety for final, and then changing the value since it is no longer final. For more info on this, check out the post where the idea came from.
So step by step we pass in the variable we want to manipulate and...
// Mark the field as public so we can toy with it
field.setAccessible(true);
// Get the Modifiers for the Fields
Field modifiersField = Field.class.getDeclaredField("modifiers");
// Allow us to change the modifiers
modifiersField.setAccessible(true);
// Remove final modifier from field by blanking out the bit that says "FINAL" in the Modifiers
modifiersField.setInt(field, field.getModifiers() & ~Modifier.FINAL);
// Set new value
field.set(null, newValue);
Combining this all into a new SUPER ANSWER you get.
#RunWith(PowerMockRunner.class)
#PrepareForTest()
class PrivateStaticFinalTest {
#Test
public void testMethod(){
try {
setFinalStatic(PrivateStaticFinal.class.getDeclaredField("variable"), Integer.valueOf(100));
}
catch (SecurityException e) {fail();}
catch (NoSuchFieldException e) {fail();}
catch (Exception e) {fail();}
assertEquals(PrivateStaticFinal.method(), Integer.valueOf(101));
}
static void setFinalStatic(Field field, Object newValue) throws Exception {
field.setAccessible(true);
// remove final modifier from field
Field modifiersField = Field.class.getDeclaredField("modifiers");
modifiersField.setAccessible(true);
modifiersField.setInt(field, field.getModifiers() & ~Modifier.FINAL);
field.set(null, newValue);
}
}
Update
The above solution will work only for those constants which is initialized in static block.When declaring and initializing the constant at the same time, it can happen that the compiler inlines it, at which point any change to the original value is ignored.