`@Configuration` classes can no longer be `abstract` without `@Bean` methods

[pnavato]

I have just upgraded to spring-boot 3.4.4 (I have only changed the version number of spring-boot-starter-parent), and several tests fail with an error message like the following.

Error creating bean with name 'MyAbstractTest': Failed to instantiate [com.mycompany.myapp.MyAbstractTest]: Is it an abstract class?

These tests extend an abstract class named, let's say MyAbstractTest, that is annotated with:

@ExtendWith(SpringExtension.class)
@Configuration
@ContextConfiguration(classes = MyAbstractTest.class)

The tests work again if I move @ContextConfiguration to each concrete subclass and reference the concrete subclass:

@ContextConfiguration(classes = MyConcreteTest.class)

This change is not needed with spring-boot 3.4.3, so I assume it's a regression, isn't it?

[sbrannen]

Hi @pnavato,

Congratulations on submitting your first issue for the Spring Framework! 👍

I tested against 6.1.x, 6.2.x, and main, and I always get an exception similar to the following.

Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [example.MyAbstractTest]: Is it an abstract class?
	at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:212)
	at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:94)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1331)
	... 32 more
Caused by: java.lang.InstantiationException
	at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:499)
	at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:480)
	at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:195)
	... 34 more

If you would like for us to look into this, please provide a sample application that we can download and run which demonstrates that your original code did not result in such an exception. You can provide a ZIP file attached to this issue or, preferably, a public Git repository that we can clone.

Thanks

[pnavato]

Here is a test case that works with spring-boot 3.4.3 (actual version in the pom) and fails if you upgrade to 3.4.4: testcase.zip.