i am new to junit so any help is appreciated.
I have a class called sysconfig.java for which i have written a
junit class file called TestSysconfig.java that tests some methods in the sysconfig.java.
The method that i am testing in sysconfig.java calls another class file "ethipmapping.java"
i have created a mock of this class file as Testethipmapping.java.
so my question is how do i tell sysconfig.java to call this mock object?
instead of mixing "new" operators with the class you're testing, you'll need to pass in your test instance of ethipmapping to the sysconfig class you are testing, either in the constructor, or via a setter. so, your class you are testing will look something like:
private EthipMapping mapping;
public Sysconfig(EthipMapping mapping) {
this.mapping = mapping;
}
public String someMethodIWantToTest() {
return mapping.doSomeStuffThatReturnsAString();
}
problems like this are why dependency injection frameworks like spring and google guice are so popular, although for simple cases like the above you don't need them.
You may be interested in Mockito.
so my question is how do i tell sysconfig.java to call this mock object?
By calling it. Wherever you created 'ethipmapping' object before (new ethipmapping()), you'll have to create Testethipmapping.
There are other options not involving changes in sysconfig.java, but it's difficult to give specific advice without seeing the code.
Related
So I am writing a class which I want to follow the best practices and be testable.
I have a new object to be created inside it. So, I am following the factory pattern to achieve it.
public class Apple {
// factory object injected in class
private SeedFactory seedFactory;
// Method to be tested
public void myMethod(String property1, int property2, String depends) {
// Just to set the necessary parameter
seedFactory = new SeedFactory(property1, property2);
// Factory pattern intact. Instance generation depends on only one parameter
SeedFactory result = seedFactory.getInstance(depends);
}
}
EDIT: Adding code for factory as well.
public class SeedFactory{
String property1;
int property2;
SeedFactory(property1,property2){
this.property1 = property1;
this.property2 = property2;
}
SeedFactory getInstance(int depends){
if(depends == 1)
{ // do stuff }
else{ // do stuff and return instance }
Now, before I actually create the new object, I have to make sure that I set two properties for the new instance to be generated, which are needed to be present irrespective of the type of instance generated by the factory. depends is the actual parameter which tells the factory what instance to return.
Now, as far as testability of this code is concerned, I can user PowerMockito to mock the factory object using whenNew but using PowerMockito is not a choice. I have to make it testable without it.
Also, I have tried to encapsulate the new call within a one line function and then use spy. But I want to avoid using spy, since it is not considered a good practice, in context of where this code is being used as a whole.
So my question is, Is there any way, without using PowerMockito, to re-write this class so that it can be unit tested properly?
If the instance to be generated needed only one parameter, then it would have been trivial. However, I don't want to pass more than one parameter to getInstance().
SeedFactory is not Apple's dependancy but your method depends on SeedFactory which has "uses" relationship. So to define proper relation i would suggest you use "USES" relation as below:
public void myMethod(SeedFactory seedFactory, String depends){ // Method to be tested
Now you could mock SeedFactory and can unit test it appropriately.
I think you're doing something wrong.
If SeedFactory isn't an Apple's dependency but an internal concern, hence you don't need to mock a SeedFactory to test Apple. You should test the public API provided by Apple only.
If SeedFactory is an Apple's dependency, so it definitely should be injected.
I am new to Spring and JUnit. I need to mock a class which is derived from ApplicationContextAware class which is inside my toBeTested(getList) method. In the following short code snippet, I need to test the getList method in abc class.
I am able to mock ModulesConfigRegistry because there is a setter for it. But I am not able to mock ModuleConfig and ListProvider. Both ModulesConfigRegistry and ModuleConfig have implemented ApplicationContextAware so it returns classes from bean. ListProvider.getList(lst.getList in code) is the method which makes further calls up to database and is required to be mocked. Appreciate your help in advance. Code sample will be helpful as I am new to Spring and JUnit.
class abc {
private ModulesConfigRegistry modulesConfigRegistry;
public void setModulesConfigRegistry(ModulesConfigRegistry modulesConfigRegistry) {
this.modulesConfigRegistry = modulesConfigRegistry;
}
public List getList(String name, String moduleName)
{
ModuleConfig moduleConfig = modulesConfigRegistry.getModuleConfig(moduleName);
Object mlist = moduleConfig.getListProvider(name);
if(mlist instanceof ListProvider)
{
ListProvider lst = (ListProvider)mList;
}
return lst.getList("abc");
}
}
Maybe there is another more simple way to achieve this (not mandatory the best). In my experience I've used Reflection in Java when it's up to Unit-testing. After all, to me the main purpose of the unit tests is to simply exercise smallest testable part and nothing more. That's why I simply use my dummy-test-object and get/set fields/properties I need.
But one thing that must be considered here is that reflection allows code to perform operations that would be illegal in non-reflective code, such as accessing private fields and methods, the use of reflection can result in unexpected side-effects. So if you know what your doing it's a good alternative.
Since you already using
JUnit
One very common use case in Java is the usage with annotations. JUnit 4, for example, will use reflection to look through your classes for methods tagged with the #Test annotation, and will then call them when running the unit test.
If you want to consider it and use it - here you can find some good examples.
Cheers.
One approach here is create mock objects for each object that you need to interact with ModuleConfig and ListProvider
#RunWith(MockitoJUnitRunner.class)
public class abcTest{
#InjectMocks
private abc abcInstance;
#Mock
private ModulesConfigRegistry modulesConfigRegistry ;
#Test
private voidTestGetList(){
//Create the mock and interactions
ModuleConfig moduleConfigMock = Mockito.mock(ModuleConfig.class);
ListProvider listProviderMock = Mockito.mock(ListProvider.class);
ArrayList listToReturn = new ArrayList();
Mockito.when(modulesConfigRegistry.getModuleConfig(Mockito.anyString())).thenReturn(moduleConfigMock);
Mockito.when(moduleConfigMock.getListProvider(Mockito.anyString())).thenReturn(listProviderMock);
Mockito.when(listProviderMock.getList(Mockito.anyString())).thenReturn(listProviderMock);
//Call real method
List resultList = abcInstance.getList("stringInput1", "stringInput2");
//Make assertions
}
}
Basically you need to create mock objects for any of the instances that you get from a mock object and use mockito to define the result of its method.
Other options is create a new class that implements or is a subclass of the returned object type and override the methods.
I have a class which takes a message with payload String.
The payload is then split and used to create an Entity which is passed to DAOInterface to persist.
How can you test the call daoInterface.insert(entity) has been made?
To Mock the DAOInterface and then verify the call to DAO requires the entity in the test class i.e.
verify(daoInterface).insert(entity);
Is this bad design i.e. creating the entity at this stage? Should the Sting[] split be passed to the DAOImplementaion and initialized there. Example problem,
public class ServiceClass {
#AutoWire
private DAOInterface daoInterface;
public void serviceMessage(Message<String> message) {
MessageHeaders mh = new MessageHeaders(message.getHeaders());
String[] split = ((String) mh.get("payload")).split("_");
code omitted
...
String type = mh.get("WhatType");
Entity entity = new Entity(split[0], split[1], split[2]);
if (type.equals("one"))
{
daoInterface.insert(entity); //How to test?
}
else
{
if (type.equals("two"))
{
doaInterface.modify(entity); //How to test?
}
}
}
}
You can verify with Mockito Matchers.
If you only care that the method is called with some Entity, you can verify that with
verify(daoInterface).insert(any(Entity.class));
If you care about which Entity, and the Entity class has an equals method, you can make an entity that should be equal to the one created and verify with
verify(daoInterface).insert(eq(expectedEntity);
If it's more complex than either of these cases, you can also write your own argument matchers.
The easiest thing you can do is injecting another collaborator to the service which will transform payload to Entity. This way you can keep control on object creation (Inversion of Control). Something like the example below injected to the ServiceClass should do the job:
interface PayloadTransformer {
public Entity transform(String payload);
}
This way your code will be easy to test and you split responsibilities which is usually a good thing. Have a look on Single Responsibility principle
Pushing transformation logic down to dao is almost never a good idea.
BTW. you can write else if without additional brackets and indentations. It's more readable like:
if (a) {
// do something
} else if (b) {
// do something
} else {
// do something
}
The last advice ServiceClass is really poor name for class. The word class is redundant here. Just name it Service, EntityService, MessageService or something which fits your case well.
I wouldn't name field with suffix *Interface as well. Underneath is some implementation injected, I assume. Better name it entityDao or just dao. It's up to you though :)
If you use a test framework like PowerMock, you can invoke private constructors and private methods in your test. This makes it easy to inject mock objects like a mock DAOInterface so you can retrieve it later and test it's been called.
For example, in PowerMock, to call a private constructor:
public class ServiceClass{
#Autowire
private final DAOInterface dao;
public ServiceClass() {
}
private ServiceClass(DAOInterface dao) {
this.dao = dao;
}
}
You simply do:
PrivateConstructorInstantiationDemo instance = WhiteBox.invokeConstructor(
PrivateConstructorInstantiationDemo.class,
new MockDAOInterface() );
So if you're using a dependency inject framework like above, this dovetails nicely. You don't normally have the dependency injection working during test, since it usually requires booting a large chunk of code with a lot of configuration.
By adding a single private constructor, you avoid breaking encapsulation, but you can still inject your mock object into the code during test with a test framework like PowerMock. This is considered best practice.
You could break encapsulation and add publicly accessible methods or ctors to the SeviceClass, but if you don't need them for your design it's not good practice to add them only for test. That's why people put such effort into bypassing encapsulation in frameworks like Mockito and PowerMock. It's not just a dodge around private code, it's because you want to keep the encapsulation while still being able to test.
EDIT:
If you're not familiar with making mock objects, you should do some Google searches on the subject. It's very common and a good skill to have. With the above code, you could make your own mock object. But making mocks is so common that most test frameworks will do this for you.
For example, in PowerMock, I just looked at their page on making mocks here. You can make a mock like this
DAOInteface myMock = createMock(DAOInterface.class);
You can then ask the mock to verify that methods are called:
expect(myMock.someMethod());
Now the mock 'expects' that method to be called, and if it isn't, it'll generate an error for your test. Pretty sweet actually.
You can also return values from a call:
expect(myMock.insert()).andReturn("Test succeeded");
so your code would then see the value "Test succeeded" when it called that method. I don't see that 'insert' does return a value, that's just an example.
I am working on a project where I am using MyBatis annotations as persistence framework. Therefore, I have to create an interface for the 'mapper' and compose the mapper in the service like :
class XYZServiceImpl{
public XYZMapper getXYZMapper(){
return SessionUtil.getSqlSession().getMapper(XYZMapper.class)
}
}
Now while unit testing the service with Mockito, I am trying to inject a mock for the mapper. But since I am injecting mock in an instance of XYZService, how can mock a method of the service itself, in this case getXYZMapper() is what I am trying to stub. Although I have got a solution of creating the instance XYZMapper in the service and not call on demand like the above code does something like :
Class XYZServiceImpl{
XYZMapper mapper;
public void useXYZMapper(){
mapper = SessionUtil.getSqlSession().getMapper(XYZMapper.class);
}
}
But that would bring a lot of code changes (ofcourse I can refactor) but is there a way to achieve without having to make code changes?
Also what would be a 'purist' way to have a mapper instance in the class is it the method 1 that is better than method 2 in terms of performance?
EDIT : Here XYZMapper is an interface. Something like :
public interface XYZMapper{
#Select("SELECT * FROM someclass WHERE id = #{id}")
public SomeClass getSomeClass(int id);
}
EDIT : I am facing a similar situation but with a variance that I have a service that I do want to test like XYZServiceImpl. Now it has a method getXYZDetails() which has a lot of business logic handled within the service. Now if getXYZDetails looks like the following :
public XYZDetails getXYZDetails(int id){
XYZDetails details = new XYZDetails();
details.set1Details(fetchSet1Details(id));
//Perform some business logic
details.set2Details(fetchSet2Details(id));
if(details.set2Details() != null){
for(int i = 0; i < details.set2Details().size(); i++){
flushTheseDetails(i);
}
}
.
.
}
Kindly notice that fetchSet1Details(), fetchSet2Details(), flushTheseDetails are public service, public and private service respectively.
I want to know of a method that can mock/stub these methods while testing getXYZDetails() thus enabling me to
There are several options you can use.
Inject dependency
This works only for simple methods like getXYZMapper when method only returns external dependency of you object. This may require to create new XYZServiceImpl instances if for example mapper is bound to connection which is opened per request.
Encapsulate method behavior in object
Another way to achieve similar result is to use a factory or service locator
like this:
public class XYZServiceImpl {
public XYZServiceImpl(XYZMapperFactory mapperFactory) {
this.mapperFactory = mapperFactory;
}
public XYZMapper getXYZMapper() {
return mapperFactory.getMapper();
}
}
This will allow you easily substitute factory in test with implementation which returns mock mapper.
The similar approach can be used for other methods fetchSet1Details, fetchSet2Details, flushTheseDetails that is moving them to other class or classes. If the method contains complex (and may be loosely related) logic it is a good candidate to be moved in separate class. Think about what these methods do. Usually you can move some essential and unrelated part of them to other class or classes and this makes mocking them much easier.
Subclass
This is not recommended but in legacy code sometimes is very helpful as a temporary solution.
In your test subclass you class under test and override methods you need:
#Test
public void someTest() {
XYZServiceImpl sut = new XYZServiceImpl() {
public XYZMapper getXYZMapper() {
return mapperMock;
}
public Whatever fetchSet1Details() {
return whateverYouNeedInTest;
}
}
sut.invokeMethodUnderTest();
}
The only thing you may need to do is to change access modifier of private method to package-private or protected so you can override them.
Spying
This method in also discouraged but you can use mockito spies:
XYZServiceImpl realService = new XYZServiceImpl();
XYZServiceImpl spy = Mockito.spy(realService);
when(spy.fetchSet1Details()).thenReturn(whaeveryouneed);
when(spy.getXYZMapper()).thenReturn(mockMapper);
spy.methodUnderTest();
I would suggest the "purist" way of doing this is to accept an XYZMapper instance in your constructor and store it in a local field.
In production use, you can pass an e.g. SQLXYZMapper, which will interact with your database. In test use, you can pass in a mocked object that you can verify interactions with.
Imagine the following class
public class ClassToBeTested{
private AnotherClass otherClass;
public void methodToBeTested(){
otherClass = new AnotherClass();
String temp = otherClass.someMethod()
// ...some other code that depends on temp
}
}
Now, if methodToBeTested was designed to accept an instance of AnotherClass I could easily create a mock of AnotherClass and tell Mockito to return a value i prefeer when someMethod() is called. However as the above code is designed AFAIK it's not possible to mock AnotherClass and testing this method will depend on what someMethod() returns.
Is there anyway I can test the above code without beeing dependent on what someMethod() returns using Mockito or any other framework?
If available you can use the Spring ReflectionTestUtils setField method:
http://static.springsource.org/spring/docs/2.5.x/api/org/springframework/test/util/ReflectionTestUtils.html#setField%28java.lang.Object,%20java.lang.String,%20java.lang.Object%29
If not write your own its pretty straight forward using reflection, some info here:
http://www.java2s.com/Code/Java/Reflection/Setprivatefieldvalue.htm
Something like the below, you will need additional error handling to get this to work properly:
public void setField(Object obj, String fieldName, Object value) {
Field f = obj.getDeclaredField(fieldName);
f.setAccessible(true);
f.set(obj, value);
}
It can then be called like this:
setField(objUnderTest, "fieldToSet", mockObject);
edit
I have just noticed that you are instantiating it inside the method. If that is absolutely necessary then you should follow the possible duplicate link posted by cyroxx.
Although that practice is often a sign of bad design so if you can take it out I would.
Setting the field by reflection as suggested in the other answer will work.
But if you're doing this sort of thing often, I'd recommend PowerMock (in conjunction with Mockito) or JMockIt to achieve this. Both allow you to mock constructors, statics, final fields... in short, just about anything. Very useful with legacy code.
However, when you're writing new code, and your class has a dependency on another class that you want to isolate in this way, you should consider changing the design so that the other object is passed in to your class instead of being instantiated by it. Search for "Dependency injection" and you'll find plenty...
As a quick fix, I usually wrap the call to new:
protected newAnotherClass() { return new AnotherClass(); }
That way, I can overwrite this method from a unit test. It's dirty but it's quick :-)
Here is a JMockit test which does what you want, very simply:
#Test
public void testTheMethodToBeTested(#Mocked final AnotherClass dep)
{
new NonStrictExpectations() {{ dep.someMethod(); result = "whatever"; }};
new ClassToBeTested().methodToBeTested();
new Verifications() {{
// verify other calls to `dep`, if applicable...
}};
}