@Autowired, @Component and testing

Question

How would you go about integration testing a spring application that is annotation-configured and component-scanned and does not have an XML configuration at all? I'm hitting a wall with the need to replace production components with testing components without actually resorting to xml configuration or reflection injections to all the @autowired parts.

Example:

interface A {...}

@Component
class AImpl implements A {
    ...
}


interface B {...}

@Component 
class BImpl implements B {
    @Autowired A a;
    ...
}


interface C {...}

class CImpl implements C {
    @Autowired B b;
    ...
}

then in my test I want to use ATestImpl, but I only have access to C (integration testing C).

How would you go about doing that?

Tomasz Nurkiewicz · Accepted Answer · 2011-07-12 20:28:16Z

10

Take advantage of @Primary annotation:

@Service
@Primary
public class TestA implements A {
  //...
}

If there is more than one bean implementing A, Spring will prefer the one annotated with @Primary. If you place TestA class in /src/test/java, it will only be picked up during test execution, on normal context startup Spring won't see TestA and use only avaialble AImpl.

answered Jul 12, 2011 at 20:28

Tomasz Nurkiewicz

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2 Comments

Ran Biron Over a year ago

oooh. nice. Didn't know that even exist. Thanks! I'll mark this as accepted once I verify and understand how to use one "primary" service for one test, and another for another test (e.g. ATestImpl1 and ATestImpl2).

Tomasz Nurkiewicz Over a year ago

Using different implementations for different tests might be tricky: I guess you are searching for beans through CLASSPATH scanning and if Spring finds more than one @Primary service you're in trouble.

JB Nizet · Accepted Answer · 2011-07-12 20:25:50Z

2

Use a dedicated spring context XML file where you override AImpl with an instance of ATestImpl. Of course, it uses XML, but I don't see any other solution (other than repackaging the application with your ATestImpl annotated class instead of the AImpl one)

answered Jul 12, 2011 at 20:25

JB Nizet

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2 Comments

Lenik Over a year ago

+1, I'd prefer to use a test XML, @Primary not always work as expected.

Ran Biron Over a year ago

I went through all the trouble of using annotations to avoid adding XMLs to my project. Why would I want to add them to the tests? That would require me (and all other developers) to learn and maintain TWO different configuration mechanisms - XML and annotations.

Alex Barnes · Accepted Answer · 2011-07-12 22:09:18Z

1

The new Bean Profile features in Spring 3.1 address the need to swap injected components for testing by defining profiles e.g. test, production etc.

The link to the blog post is here. The Spring team have today released the second milestone release of Spring 3.1.

answered Jul 12, 2011 at 22:09

Alex Barnes

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1 Comment

Ran Biron Over a year ago

Interesting. still not in release though. Pity.

Ralph · Accepted Answer · 2011-07-13 06:28:05Z

1

You can use a special component scan for your test, that exclude the "normal" class and add the test class.

If you have several different test classes, then they should not have a @Component Annotation (or @Service, ...). Instead they should be loaded by an XML Bean declaration. So you can have different XML files for different setups.

<context:component-scan base-package="com.queomedia.sgcrm.base">
    <context:exclude-filter expression="com\.example\.AImpl" type="regex"/>
</context:component-scan>

<bean class="com.example.ATestImpl"/>

answered Jul 13, 2011 at 6:28

Ralph

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Comments

Jon Griffith · Accepted Answer · 2015-11-07 07:18:40Z

1

Using Spring annotation config classes, code the @Bean methods to interfaces. The prod config can perform a componentscan on the high-level package(s) to load the prod objects and the test configs can individually specify beans to return the test versions of your objects. This works very well for component testing where faking service calls and DAO objects is necessary.

answered Nov 7, 2015 at 7:18

Jon Griffith

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