TDD Testing of Dependancy Injection in Spring

Spring relies very heavily on dependancy injection and when writing integration tests the first thing that must work before you even try to connect to things like your database is that all your beans must be correctly injected.

So before I get all excited and start writing tests that read or write to the database I write a very simple test to check that everything has been injected correctly.

public class FooServiceIntegrationTest extends BaseIntegrationTester{
 private FooService fooService;

 public void setFooService(BulkUploadService aFooService){
   fooService = aFooService;
 }

 public void testInjection() throws Exception{
   assertNotNull("FooService not injected", fooService);
 }
}

Strictly speaking this test testInjection is not needed at this stage because the test will fail if the injection of this primary bean fails.

Ok so I need to create the bean.

<bean id="fooService" name="fooService" class="uk.co.foo.FooServiceImpl">
</bean>

The test will now pass.

The test now gets more useful as I now extend the test to see if FooService has its beans injected successfully.

public class FooServiceIntegrationTest extends BaseIntegrationTester{
 private FooService fooService;

 public void setFooService(BulkUploadService aFooService){
   fooService = aFooService;
 }

 public void testInjection() throws Exception{
   assertNotNull("FooService not injected", fooService);
   assertNotNull("FooService not injected", fooService.getBarDao());
 }
}

Now this will not compile at first as fooService.getBarDao() does not exist.
I add this to the interface and implement the method and re-run the test,

The test fails as we have not set the property on the bean so lets do that.

<bean id="fooService" name="fooService" class="uk.co.foo.FooServiceImpl">
<property name="barDao" ref="barDao" />
</bean>

Assuming barDao has also been configured then the test will now pass.

Possibly others do this, I do not know but I have found this little test invaluable as a precursor to grander integration tests later on.

BTW BaseIntegration tester does little more than extend AbstractTransactionalDataSourceSpringContextTests and implement the method getConfigLocations()