Spring Incorrect handling of MockedStatic with nested tests

Affects: Spring Boot 3.2.2, spring-test 6.1.3

---

Below is a cut down example showing the issue:

package com.example.demo;

import org.junit.jupiter.api.Nested;
import org.junit.jupiter.api.extension.ExtendWith;
import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.ValueSource;
import org.mockito.Mock;
import org.mockito.MockedStatic;
import org.mockito.junit.jupiter.MockitoExtension;
import org.springframework.test.context.junit.jupiter.SpringExtension;

import java.util.UUID;

import static org.assertj.core.api.Assertions.assertThat;

//@ExtendWith(MockitoExtension.class)
@ExtendWith(SpringExtension.class)
class DemoApplicationTests {

    private static final UUID uuid = UUID.randomUUID();

    @Mock
    private MockedStatic<UUID> mockedStatic;

    @Nested
    class nested {

        @ParameterizedTest
        @ValueSource(ints = { 1, 2 })
        void shouldReturnConstantValue(int run) {
            mockedStatic.when(UUID::randomUUID).thenReturn(uuid);

            UUID result = UUID.randomUUID();

            assertThat(result).isEqualTo(uuid);
        }
    }
}

The problem is that the second time the test runs, the MockedStatic is not properly closed, and there's an initialisation error when creating the MockedStatic the second time:

org.mockito.exceptions.base.MockitoException: 
For java.util.UUID, static mocking is already registered in the current thread

To create a new mock, the existing static mock registration must be deregistered

If the MockedStatic is moved into the inner class, it works fine, but in the real test I'm working on, I don't want to structure it like that.

It is an inconsistency between the SpringExtension and the MockitoExtension. If you comment the SpringExtension line, and uncomment the MockitoExtension, then the test works fine.

Comment From: bernie-schelberg-invicara

I'll just add: the issue is not related to the @ParameterizedTest. That was just a more concise way to demonstrate the issue. The issue also occurs with two separate tests in the nested class.

Comment From: bernie-schelberg-invicara

My mistake, it's a Spring Boot issue, not Spring Framework. I've moved the issue to the spring-boot project: https://github.com/spring-projects/spring-boot/issues/39270