Provide Mockito with a MockResolver that removes Spring-created proxies

spring-boot-project/spring-boot-test/src/main/java/org/springframework/boot/test/mock/mockito/SpringBootMockResolver.java

+/*
+ * Copyright 2012-2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.test.mock.mockito;
+
+import org.mockito.plugins.MockResolver;
+
+import org.springframework.test.util.AopTestUtils;
+
+/**
+ * A {@link MockResolver} for testing Spring Boot applications with Mockito. Resolves
+ * mocks by returning the {@link AopTestUtils#getUltimateTargetObject(Object) ultimate
+ * target object} of the instance.
+ *
+ * @author Andy Wilkinson
+ * @since 2.4.0
+ */
+public class SpringBootMockResolver implements MockResolver {
+
+	@Override
+	public Object resolve(Object instance) {
+		return AopTestUtils.getUltimateTargetObject(instance);
+	}
+
+}

spring-boot-project/spring-boot-test/src/main/resources/mockito-extensions/org.mockito.plugins.MockResolver

+org.springframework.boot.test.mock.mockito.SpringBootMockResolver
\ No newline at end of file

spring-boot-project/spring-boot-test/src/test/java/org/springframework/boot/test/mock/mockito/SpringBootMockResolverIntegrationTests.java

+/*
+ * Copyright 2012-2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.test.mock.mockito;
+
+import org.junit.jupiter.api.Test;
+import org.mockito.internal.configuration.plugins.Plugins;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Integration tests for {@link SpringBootMockResolver}.
+ *
+ * @author Andy Wilkinson
+ */
+class SpringBootMockResolverIntegrationTests {
+
+	@Test
+	void customMockResolverIsRegisteredWithMockito() {
+		assertThat(Plugins.getMockResolvers()).hasOnlyElementsOfType(SpringBootMockResolver.class);
+	}
+
+}