I have a question regarding one of the feature of mockito. On several blogs I have read that mocking constructor is not possible through mockito.
For one of my test case, currently it is done through powermockito but I want to remove it due to some performance issues.
Currently the code looks something like this:
Actual class:
public class TestClass {
private ClassB classB;
public TestClass(ClassB classB) {
this.classB = classB;
}
}
In my test class, I have code like this:
TestClass testClass = Mockito.mock(TestClass.class);
PowerMockito.whenNew(TestClass.class).withArguments(this.classB)
.thenReturn(testClass);
So could anyone suggest me, is there any other way possible by which I can achieve the same thing through mockito? Also on some blogs, I found that injection a public method with constructor of the class inside and then mocking that method can do the trick. But wanted to know all other options to analyze.
Thanks
-Sam
I am not sure if that can help you.
class MyClass {
private final MySecondClass clazz;
MyClass(MySecondClass clazz) {
this.clazz = clazz;
}
public boolean executeDoSomething() {
return clazz.doSomething();
}
}
And in the test you could mock the inner class:
#RunWith(MockitoJUnitRunner.class)
public class MyClassTest {
#Test
public void MyClassTest() {
MySecondClass mockedPerformer = Mockito.mock(MySecondClass.class);
MyClass clazz = new MyClass(mockedPerformer);
clazz.executeDoSomething();
}
}
I hope this helps you.
Related
Unit test noob here.
I have three classes: Db1Dao, Db2Dao, ExecuteClass where Db1Dao, Db2Dao are database access objects for two different databases. My goal is to fetch some data from db1 using Db1Dao and run executeClass.execute() to "put" the processed data into db2 using Db2Dao.
My ExecuteClass looks like this:
class ExecuteClass {
private Db1Dao db1Dao;
private Db2Dao db2Dao;
public void execute() {
...
List<String> listOfString = getExternalData(someParam);
List<Metadata> metadatum = db1Dao.get(someInputs);
... I do something to generate a list of new class `A` based on listOfString & metadatum ...
try {
db2Dao.put(listOfA);
} catch (PutException e){
...
}
}
public List<String> getExternalData(SomeClass someParam){
... do something
return listOfString;
}
}
Now I want to test:
Given a specific listOfString (returned by getExternalData) and a specific metadatum (returned by db1Dao.get):
Will I get the desired listOfA?
Am I able to call db2Dao.put and its input parameter is listOfA?
Particularly, I have hard-coded sample listOfString and metadatum and desired listOfA (and they will be passed via an object MockData, see the following code) but I don't know how to write the test using Mockito. The following is a test class I wrote but it does not work:
class TestClass extends BaseTest {
#Mock
private Db1Dao db1Dao;
#Mock
private Db2Dao db2Dao;
private ExecuteClass executeClass;
#BeforeEach
public void setUp() {
MockitoAnnotations.initMocks(this);
executeClass = new ExecuteClass(db1Dao, db2Dao);
}
#ParameterizedTest
#MethodSource("MockDataProvider")
public void executeClassTest(final MockData mockData) throws PutException {
Mockito.when(db1Dao.get(Mockito.any(), ...))
.thenReturn(mockData.getMetadatum());
ExecuteClass executeClassSpy = Mockito.spy(executeClass);
Mockito.when(executeClassSpy.getExternalData(Mockito.any()))
.thenReturn(mockData.getListOfString());
executeClassSpy.execute();
// executeClass.execute(); not working neither...
List<A> listOfA = mockData.getDesiredListOfA();
Mockito.verify(db2Dao).put(listOfA);
}
}
Could anyone please let me know? Thank you in advance!!
You should not create a spy of the same class you want to test. Instead, try to write a unit test for the smallest amount of code (e.g. a public method) and mock every external operator (in your case Db1Dao and Db2Dao).
If testing a public method involves calling another public method of the same class, make sure to mock everything inside the other public method (in your case getExternalData). Otherwise, this other public method might be a good candidate for an extra class to have clear separation of concerns.
So, remove the ExecuteClass executeClassSpy = Mockito.spy(executeClass); and make sure you setup everything with Mockito what's called within getExternalData.
To now actually, verify that Db2Dao was called with the correct parameter, either use your current approach with verifying the payload. But here it's important to 100% create the same data structure you get while executing your application code.
Another solution would be to use Mockito's #Captor. This allows you to capture the value of why verifying the invocation of a mock. Later on, you can also write assertions on the captured value:
#Captor
private ArgumentCaptor<ClassOfListOfA> argumentCaptor;
#Test
public void yourTest() {
Mockito.verify(db2Dao).put(argumentCaptor.capture());
assertEquals("StringValue", argumentCaptur.getValue().getWhateverGetterYouHave);
}
The following code worked for me.
I partially accepted #rieckpil's answer. I used #Captor which is very handy.
The reason I had to mock getExternalData() is because its implementation is still a "TODO".
class TestClass extends BaseTest {
#Mock
private Db1Dao db1Dao;
#Mock
private Db2Dao db2Dao;
#Captor
private ArgumentCaptor<List<A>> argumentCaptor;
private ExecuteClass executeClass;
#BeforeEach
public void setUp() {
MockitoAnnotations.initMocks(this);
executeClass = new ExecuteClass(db1Dao, db2Dao);
}
#ParameterizedTest
#MethodSource("MockDataProvider")
public void executeClassTest(final MockData mockData) throws PutException {
Mockito.when(db1Dao.get(Mockito.any(), ...))
.thenReturn(mockData.getMetadatum());
ExecuteClass executeClassSpy = Mockito.spy(executeClass);
Mockito.when(executeClassSpy.getExternalData(Mockito.any()))
.thenReturn(mockData.getListOfString());
executeClassSpy.execute();
List<A> listOfA = mockData.getDesiredListOfA();
Mockito.verify(db2Dao).put(argumentCaptor.capture());
assertEquals(listOfA, argumentCaptor.getValue());
}
}
How to mock "System.getenv("...")" in JUnit.
Currently I am doing:
#RunWith(Parameterized.class)
#PowerMockRunnerDelegate(PowerMockRunner.class)
#PrepareForTest(System.class)
public class TestClass extends BaseTest {
public TestClass(String testCase) {
this.testCase = testCase;
}
#Before
#Override
public final void initTable() throws Throwable {
super.initTable();
PowerMockito.mockStatic(System.class);
PowerMockito.when(System.getenv("ENV_VAR1")).thenReturn("1234");
}
...
}
I am using both PowerMock and Parameterizedrunner.
I am getting below exception for line:
PowerMockito.when(System.getenv("ENV_VAR1")).thenReturn("1234");
Exception:
org.mockito.exceptions.base.MockitoException:
'afterPropertiesSet' is a *void method* and it *cannot* be stubbed with a *return value*!
Voids are usually stubbed with Throwables:
doThrow(exception).when(mock).someVoidMethod();
***
Use the #RunWith(PowerMockRunner.class) annotation at the class-level of the test case.
Use the #PrepareForTest({ClassThatCallsTheSystemClass.class}) annotation at the class-level of the test case.
Example with using EasyMock
public class SystemClassUser {
public String performEncode() throws UnsupportedEncodingException {
return URLEncoder.encode("string", "enc");
}
}
And test
#RunWith(PowerMockRunner.class)
#PrepareForTest( { SystemClassUser.class })
public class SystemClassUserTest {
#Test
public void assertThatMockingOfNonFinalSystemClassesWorks() throws Exception {
mockStatic(URLEncoder.class);
expect(URLEncoder.encode("string", "enc")).andReturn("something");
replayAll();
assertEquals("something", new SystemClassUser().performEncode());
verifyAll();
}
}
From:
https://github.com/powermock/powermock/wiki/MockSystem
So, you should add a class that uses the System.getenv, not the System class to #PrepareForTest.
This post explains why it should be done in such way.
Also, I'd like to recommend to use the System Rules library for your case. It has a good way to stub environment variables. PowerMock modifies a class byte code, so it makes test slowly. And even if it not modify a class it at least read class from disk.
I remember reading an example which shows how to set member of a mocked object, for ex:
MyClass mockedClass = mock(MyClass.class);
//and something like this to set `someVariable` with some value
Mokito.set(mockedClass.someVariable, actual_value_intended_to_be_set);
Unfortunately I am not able to find that link again. Can someone give a reverence to
such examples or explain it here ?
If you want your mock's outward behavior to look like mockedClass.someVariable has actual_value_intended_to_be_set, you can write:
when(mockedClass.getSomeVariable()).thenReturn(actual_value_intended_to_be_set);
Happy mocking!
Is 'this' perhaps what you are looking for?
public class MyClassTest {
#InjectMocks private MyClass mockedClass;
#BeforeMethod(groups = { "unit" })
public void setup() throws Exception {
mockedClass = new MyClass();
MockitoAnnotations.initMocks(this);
Mockito.when(getSomeVariable()).thenReturn(actual_value_intended_to_be_set);
}
#Test(groups = { "unit" })
public void testMyClass() throws Exception {
//almost too trivial an example since you just setup this.
Assert.assertEquals(getSomeVariable(), actual_value_intended_to_be_set);
}
}
It creates your MyClass object and sets the return value as well.
I'm writing unit tests using Mockito and I'm having problems mocking the injected classes. The problem is that two of the injected classes are the same type, and only differentiated by their #Qualifier annotation. If I tried to simply mock SomeClass.class, that mock is not injected and that object is null in my tests. How can I mock these objects?
public class ProfileDAL {
#Inject
#Qualifier("qualifierA")
private SomeClass someClassA ;
#Inject
#Qualifier("qualifierB")
private SomeClass someClassB ;
//...various code, not important
}
#RunWith(MockitoJUnitRunner.class)
public class ProfileDALLOMImplTest {
#InjectMocks
private ProfileDALLOMImpl profileDALLOMImpl = new ProfileDALLOMImpl();
#Mock
private SomeClass someClassA;
#Mock
private SomeClass someClassB;
private SomeResult mockSomeResult = mock(SomeResult.class);
#Test
public void testSomeMethod() {
when(someClassA .getSomething(any(SomeArgment.class)).thenReturn(mockSomeResult);
Int result = profileDALLOMImpl.someTest(This isn't relevant);
}
}
I have tried mocking two objects with the same type with Mockito 1.9.5 using JUnit and it works.
See: http://static.javadoc.io/org.mockito/mockito-core/1.9.5/org/mockito/InjectMocks.html
Relevant type info from the doc:
"Field injection; mocks will first be resolved by type, then, if there is several property of the same type, by the match of the field name and the mock name."
And this one which seems to say you should make the mock name match the field name for all your mocks when you have two of the same type:
"Note 1: If you have fields with the same type (or same erasure), it's better to name all #Mock annotated fields with the matching fields, otherwise Mockito might get confused and injection won't happen."
Perhaps this latter one is biting you?
Just confirmed what Splonk pointed out and it works that way in Mockito 1.9.5, as soon as I removed one of the mocked classes, it failed.
So, in your case, make sure you have both of the mocked classes with the same name as in the class in your test:
#Mock
private SomeClass someClassA;
#Mock
private SomeClass someClassB;
If you don't use annotation, you get something like
public class MyClass {
private MyDependency myDependency;
public void setMyDependency(MyDependency myDependency){
this.myDependency = myDependency;
}
}
and
import org.junit.Before;
import org.junit.Test;
import static org.mockito.Mockito.*;
public class MyTest {
private MyClass myClass;
private MyDependency myDependency;
#Before
public void setUp(){
myClass = new MyClass();
myDependency = mock(MyDependency.class);
myClass.setMyDependency(myDependency);
}
#Test
public void test(){
// Given
// When
// Then
}
}
You can do just the same if your object has its dependencies specified via constructor rather than via setter. I guess your dependency injection framework can annotate the setters the same way you annotate private fields, but now your tests don't rely on any dependency injection framework.
I need some help with this:
Example:
void method1{
MyObject obj1=new MyObject();
obj1.method1();
}
I want to mock obj1.method1() in my test but to be transparent so I don't want make and change of code.
Is there any way to do this in Mockito?
The answer from #edutesoy points to the documentation of PowerMockito and mentions constructor mocking as a hint but doesn't mention how to apply that to the current problem in the question.
Here is a solution based on that. Taking the code from the question:
public class MyClass {
void method1 {
MyObject obj1 = new MyObject();
obj1.method1();
}
}
The following test will create a mock of the MyObject instance class via preparing the class that instantiates it (in this example I am calling it MyClass) with PowerMock and letting PowerMockito to stub the constructor of MyObject class, then letting you stub the MyObject instance method1() call:
#RunWith(PowerMockRunner.class)
#PrepareForTest(MyClass.class)
public class MyClassTest {
#Test
public void testMethod1() {
MyObject myObjectMock = mock(MyObject.class);
when(myObjectMock.method1()).thenReturn(<whatever you want to return>);
PowerMockito.whenNew(MyObject.class).withNoArguments().thenReturn(myObjectMock);
MyClass objectTested = new MyClass();
objectTested.method1();
... // your assertions or verification here
}
}
With that your internal method1() call will return what you want.
If you like the one-liners you can make the code shorter by creating the mock and the stub inline:
MyObject myObjectMock = when(mock(MyObject.class).method1()).thenReturn(<whatever you want>).getMock();
If you really want to avoid touching this code, you can use Powermockito (PowerMock for Mockito).
With this, amongst many other things, you can mock the construction of new objects in a very easy way.
No way. You'll need some dependency injection, i.e. instead of having the obj1 instantiated it should be provided by some factory.
MyObjectFactory factory;
public void setMyObjectFactory(MyObjectFactory factory)
{
this.factory = factory;
}
void method1()
{
MyObject obj1 = factory.get();
obj1.method();
}
Then your test would look like:
#Test
public void testMethod1() throws Exception
{
MyObjectFactory factory = Mockito.mock(MyObjectFactory.class);
MyObject obj1 = Mockito.mock(MyObject.class);
Mockito.when(factory.get()).thenReturn(obj1);
// mock the method()
Mockito.when(obj1.method()).thenReturn(Boolean.FALSE);
SomeObject someObject = new SomeObject();
someObject.setMyObjectFactory(factory);
someObject.method1();
// do some assertions
}
Both mocking of a new instance creation and static methods is possible without PowerMock in the latest mockito versions and junit5.
Take a look in the methods Mockito.mockConstruction() and Mockito.mockStatic().
In your case:
try (MockedConstruction<MyObject> myobjectMockedConstruction = Mockito.mockConstruction(MyObject.class,
(mock, context) -> {
given(mock.method1()).willReturn("some result"); //any additional mocking
})) {
underTest.method1();
assertThat(myobjectMockedConstruction.constructed()).hasSize(1);
MyObject mock = myobjectMockedConstruction.constructed().get(0);
verify(mock).method1();
}
You could avoid changing the code (although I recommend Boris' answer) and mock the constructor, like in this example for mocking the creation of a File object inside a method. Don't forget to put the class that will create the file in the #PrepareForTest.
package hello.easymock.constructor;
import java.io.File;
import org.easymock.EasyMock;
import org.junit.Assert;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.api.easymock.PowerMock;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;
#RunWith(PowerMockRunner.class)
#PrepareForTest({File.class})
public class ConstructorExampleTest {
#Test
public void testMockFile() throws Exception {
// first, create a mock for File
final File fileMock = EasyMock.createMock(File.class);
EasyMock.expect(fileMock.getAbsolutePath()).andReturn("/my/fake/file/path");
EasyMock.replay(fileMock);
// then return the mocked object if the constructor is invoked
Class<?>[] parameterTypes = new Class[] { String.class };
PowerMock.expectNew(File.class, parameterTypes , EasyMock.isA(String.class)).andReturn(fileMock);
PowerMock.replay(File.class);
// try constructing a real File and check if the mock kicked in
final String mockedFilePath = new File("/real/path/for/file").getAbsolutePath();
Assert.assertEquals("/my/fake/file/path", mockedFilePath);
}
}
If you don't prefer to use PowerMock, you may try the below way:
public class Example{
...
void method1(){
MyObject obj1 = getMyObject();
obj1.doSomething();
}
protected MyObject getMyObject(){
return new MyObject();
}
...
}
Write your test like this:
#Mock
MyObject mockMyObject;
#Test
void testMethod1(){
Example spyExample = spy(new Example());
when(spyExample.getMyObject()).thenReturn(mockMyObject);
//stub if required
doNothing().when(mockMyObject.doSomething());
verify(mockMyObject).doSomething();
}
You can do this by creating a factory method in MyObject:
class MyObject {
public static MyObject create() {
return new MyObject();
}
}
then mock that with PowerMock.
However, by mocking the methods of a local scope object, you are depending on that part of the implementation of the method staying the same. So you lose the ability to refactor that part of the method without breaking the test. In addition, if you are stubbing return values in the mock, then your unit test may pass, but the method may behave unexpectedly when using the real object.
In sum, you should probably not try to do this. Rather, letting the test drive your code (aka TDD), you would arrive at a solution like:
void method1(MyObject obj1) {
obj1.method1();
}
passing in the dependency, which you can easily mock for the unit test.