Duplicate `BeanOverrideHandler` discovered in `@Nested` test class hierarchy when upgrading to Spring 6.2.2

[bwaldvogel]

Consider the following test with nested test classes:

@SpringBootTest
class SomeTest {

    @MockitoSpyBean
    SomeService someService;

    abstract class BaseClassForNestedTests {
        @Test
        void someTest() {}
    }

    @Nested
    class SomeNestedTest extends BaseClassForNestedTests {}
}

@Service
class SomeService {
}

When upgrading Spring Boot 3.4.1 to 3.4.2 (which upgrades Spring from 6.2.1 to 6.2.2), the test starts to fail with:

Duplicate BeanOverrideHandler discovered in test class SomeTest$SomeNestedTest: [MockitoSpyBeanOverrideHandler@5c48c0c0 field = SomeService SomeTest.someService, beanType = SomeService, beanName = [null], strategy = WRAP, reset = AFTER]
java.lang.IllegalStateException: Duplicate BeanOverrideHandler discovered in test class SomeTest$SomeNestedTest: [MockitoSpyBeanOverrideHandler@5c48c0c0 field = SomeService SomeTest.someService, beanType = SomeService, beanName = [null], strategy = WRAP, reset = AFTER]
	at org.springframework.util.Assert.state(Assert.java:101)
	at org.springframework.test.context.bean.override.BeanOverrideContextCustomizerFactory.lambda$findBeanOverrideHandlers$1(BeanOverrideContextCustomizerFactory.java:55)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1596)
	at org.springframework.test.context.bean.override.BeanOverrideContextCustomizerFactory.findBeanOverrideHandlers(BeanOverrideContextCustomizerFactory.java:54)
	at org.springframework.test.context.bean.override.BeanOverrideContextCustomizerFactory.createContextCustomizer(BeanOverrideContextCustomizerFactory.java:46)
	at org.springframework.test.context.bean.override.BeanOverrideContextCustomizerFactory.createContextCustomizer(BeanOverrideContextCustomizerFactory.java:38)
	at org.springframework.test.context.support.AbstractTestContextBootstrapper.getContextCustomizers(AbstractTestContextBootstrapper.java:360)
	at org.springframework.test.context.support.AbstractTestContextBootstrapper.buildMergedContextConfiguration(AbstractTestContextBootstrapper.java:332)
	at org.springframework.test.context.support.AbstractTestContextBootstrapper.buildDefaultMergedContextConfiguration(AbstractTestContextBootstrapper.java:267)
	at org.springframework.test.context.support.AbstractTestContextBootstrapper.buildMergedContextConfiguration(AbstractTestContextBootstrapper.java:215)
	at org.springframework.test.context.support.AbstractTestContextBootstrapper.buildTestContext(AbstractTestContextBootstrapper.java:108)
	at org.springframework.boot.test.context.SpringBootTestContextBootstrapper.buildTestContext(SpringBootTestContextBootstrapper.java:111)
	at org.springframework.test.context.TestContextManager.<init>(TestContextManager.java:142)
	at org.springframework.test.context.TestContextManager.<init>(TestContextManager.java:126)
	at org.springframework.test.context.junit.jupiter.SpringExtension.getTestContextManager(SpringExtension.java:363)
	at org.springframework.test.context.junit.jupiter.SpringExtension.beforeAll(SpringExtension.java:128)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1596)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1596)

I tried to do a search to find if this issue was already reported. I found #34204 which could be related to this issue.

[sbrannen]

What happens if you declare BaseClassForNestedTests as a static nested class or as a stand-alone top-level class?

[sbrannen]

Similarly, what happens if you annotate your non-static nested base class with @NestedTestConfiguration, as follows?

@NestedTestConfiguration(EnclosingConfiguration.OVERRIDE)
abstract class BaseClassForNestedTests {
	// ...
}

Alternatively, you should be able to annotate SomeNestedTest with @NestedTestConfiguration(EnclosingConfiguration.OVERRIDE) to achieve the same effect.

[sbrannen]

I tried to do a search to find if this issue was already reported. I found #34204 which could be related to this issue.

The change in behavior that you have reported is not related to #34204 but rather results from the changes made to BeanOverrideContextCustomizerFactory and BeanOverrideHandler in conjunction with #33925 (see commit 9181cce for details).

[bwaldvogel]

What happens if you declare BaseClassForNestedTests as a static nested class or as a stand-alone top-level class?

This would work, however, in my real-world case I cannot make the base class static.

Similarly, what happens if you annotate your non-static nested base class with @NestedTestConfiguration, as follows?

@NestedTestConfiguration(EnclosingConfiguration.OVERRIDE)
abstract class BaseClassForNestedTests {
	// ...
}

This fixes the error.

[sbrannen]

This fixes the error.

Thanks for confirming that @NestedTestConfiguration allows you to address that scenario.

In light of that, I am closing this issue as "works as designed".

Cheers,

Sam