DDevelopment & Design

MapStruct mapper injection in OSGi Blueprint

What is MapStruct?According to MapStruct website:MapStruct is a code generator that greatly simplifies the implementation of mappings between Java bean types based on a convention over configuration approach. The generated mapping code uses plain metho…

What is MapStruct?

According to MapStruct website:

MapStruct is a code generator that greatly simplifies the implementation of mappings between Java bean types based on a convention over configuration approach. The generated mapping code uses plain method invocations and thus is fast, type-safe and easy to understand.

Inject MapStruct mapper in Blueprint OSGi

Such mappings are sometimes necessary in our integration projects. We also use OSGi to create our applications and Blueprint for dependency injection. Blueprin Maven Plugin makes it very easy to use, providing annotation support.

MapStruct supports component models like cdi, spring and jsr330, so generated classes could be used as beans. Fortunately, Blueprint Maven Plugin uses annotations from JSR 330, such as Singleton or Named.

The only thing we have to do is to add property componentModel with value jsr330 to a mapping interface:

@Mapper(componentModel = "jsr330")
public interface PersonMapper {
    Person toDomain(PersonDto personDto);
}

and now we can inject PersonMapper to our beans:

@Singleton
@AllArgsConstructor
public class CreatePersonHandler {
    private final PersonRepository personRepository;
    private final PersonMapper personMapper;

    // ...
}

Blueprint Maven Plugin will generate an XML file with bean PersonMapperImpl and inject it to CreatePersonHandler:

<?xml version="1.0" encoding="UTF-8"?><blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0">
    <bean id="createPersonHandler" class="com.github.alien11689.osgi.mapstructblueprint.CreatePersonHandler">
        <argument ref="personRepository"/>
        <argument ref="personMapperImpl"/>
    </bean>
    <bean id="personMapperImpl" class="com.github.alien11689.osgi.mapstructblueprint.PersonMapperImpl"/>
    <bean id="personRepository" class="com.github.alien11689.osgi.mapstructblueprint.PersonRepository"/>
</blueprint>

Generate all mappers with JSR 330 annotations

If you have multiple mappers and all of them should be beans, then you can simply add one compiler argument in configuration and all the mappers will have @Singleton and @Named annotations by default.

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    ...
    <build>
        <plugins>
            ...
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>${maven-compiler-plugin.version}</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <compilerArgs>
                        <compilerArg>
                             -Amapstruct.defaultComponentModel=jsr330
                        </compilerArg>
                    </compilerArgs>
                </configuration>
            </plugin>
            ...
        </plugins>
    </build>
</project>

Try it on your own

The code is available at Github.

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DDevelopment & Design

Thought static method can’t be easy to mock, stub nor track? Wrong!

No matter why, no matter is it a good idea. Sometimes one just wants to check or it's necessary to be done. Mock a static method, woot? Impossibru!

In pure Java world it is still a struggle. But Groovy allows you to do that really simple. Well, not groovy alone, but with a great support of Spock.

Lets move on straight to the example. To catch some context we have an abstract for the example needs. A marketing project with a set of offers. One to many.

import spock.lang.Specification

class OfferFacadeSpec extends Specification {

    OfferFacade facade = new OfferFacade()

    def setup() {
        GroovyMock(Project, global: true)
    }

    def 'delegates an add offer call to the domain with proper params'() {
        given:
            Map params = [projId: projectId, name: offerName]

        when:
            Offer returnedOffer = facade.add(params)

        then:
            1 * Project.addOffer(projectId, _) >> { projId, offer -> offer }
            returnedOffer.name == params.name

        where:
            projectId | offerName
            1         | 'an Offer'
            15        | 'whasup!?'
            123       | 'doskonała oferta - kup teraz!'
    }
}
So we test a facade responsible for handling "add offer to the project" call triggered  somewhere in a GUI.
We want to ensure that static method Project.addOffer(long, Offer) will receive correct params when java.util.Map with user form input comes to the facade.add(params).
This is unit test, so how Project.addOffer() works is out of scope. Thus we want to stub it.

The most important is a GroovyMock(Project, global: true) statement.
What it does is modifing Project class to behave like a Spock's mock. 
GroovyMock() itself is a method inherited from Specification.  The global flag is necessary to enable mocking static methods.
However when one comes to the need of mocking static method, author of Spock Framework advice to consider redesigning of implementation. It's not a bad advice, I must say.

Another important thing are assertions at then: block. First one checks an interaction, if the Project.addOffer() method was called exactly once, with a 1st argument equal to the projectId and some other param (we don't have an object instance yet to assert anything about it).
Right shit operator leads us to the stub which replaces original method implementation by such statement.
As a good stub it does nothing. The original method definition has return type Offer. The stub needs to do the same. So an offer passed as the 2nd argument is just returned.
Thanks to this we can assert about name property if it's equal with the value from params. If no return was designed the name could be checked inside the stub Closure, prefixed with an assert keyword.

Worth of  mentioning is that if you want to track interactions of original static method implementation without replacing it, then you should try using GroovySpy instead of GroovyMock.

Unfortunately static methods declared at Java object can't be treated in such ways. Though regular mocks and whole goodness of Spock can be used to test pure Java code, which is awesome anyway :)No matter why, no matter is it a good idea. Sometimes one just wants to check or it's necessary to be done. Mock a static method, woot? Impossibru!

In pure Java world it is still a struggle. But Groovy allows you to do that really simple. Well, not groovy alone, but with a great support of Spock.

Lets move on straight to the example. To catch some context we have an abstract for the example needs. A marketing project with a set of offers. One to many.

import spock.lang.Specification

class OfferFacadeSpec extends Specification {

    OfferFacade facade = new OfferFacade()

    def setup() {
        GroovyMock(Project, global: true)
    }

    def 'delegates an add offer call to the domain with proper params'() {
        given:
            Map params = [projId: projectId, name: offerName]

        when:
            Offer returnedOffer = facade.add(params)

        then:
            1 * Project.addOffer(projectId, _) >> { projId, offer -> offer }
            returnedOffer.name == params.name

        where:
            projectId | offerName
            1         | 'an Offer'
            15        | 'whasup!?'
            123       | 'doskonała oferta - kup teraz!'
    }
}
So we test a facade responsible for handling "add offer to the project" call triggered  somewhere in a GUI.
We want to ensure that static method Project.addOffer(long, Offer) will receive correct params when java.util.Map with user form input comes to the facade.add(params).
This is unit test, so how Project.addOffer() works is out of scope. Thus we want to stub it.

The most important is a GroovyMock(Project, global: true) statement.
What it does is modifing Project class to behave like a Spock's mock. 
GroovyMock() itself is a method inherited from Specification.  The global flag is necessary to enable mocking static methods.
However when one comes to the need of mocking static method, author of Spock Framework advice to consider redesigning of implementation. It's not a bad advice, I must say.

Another important thing are assertions at then: block. First one checks an interaction, if the Project.addOffer() method was called exactly once, with a 1st argument equal to the projectId and some other param (we don't have an object instance yet to assert anything about it).
Right shit operator leads us to the stub which replaces original method implementation by such statement.
As a good stub it does nothing. The original method definition has return type Offer. The stub needs to do the same. So an offer passed as the 2nd argument is just returned.
Thanks to this we can assert about name property if it's equal with the value from params. If no return was designed the name could be checked inside the stub Closure, prefixed with an assert keyword.

Worth of  mentioning is that if you want to track interactions of original static method implementation without replacing it, then you should try using GroovySpy instead of GroovyMock.

Unfortunately static methods declared at Java object can't be treated in such ways. Though regular mocks and whole goodness of Spock can be used to test pure Java code, which is awesome anyway :)
DDevelopment & Design

TouK na targach pracyTouK at the job fair

Zapraszamy na XI Targi Pracy i Praktyk dla Elektroników i Informatyków. Odwiedź nasze stoisko w dniach 4-5 marca w godz. 9:30-15:30. Politechnika Warszawska Pierwsze piętro budynku Wydziału Elektroniki i Techniki Informacyjnych Nowowiejska 15/19We invite you to 11th Job and Internship Fair for Electronic Engineers and IT Specialists. Come and visit our stand between 4-5 March 9:30 am and 15 :30 pm Warsaw University of Technology the first floor of the Electronics faculty building Nowowiejska 15/19