Use single mock when backing bean is the same instance

Fixes: quarkusio#15411

integration-tests/injectmock/src/main/java/io/quarkus/it/mockbean/SameBeanInstance.java

@@ -0,0 +1,63 @@
+package io.quarkus.it.mockbean;
+
+import javax.enterprise.context.ApplicationScoped;
+import javax.inject.Inject;
+
+public class SameBeanInstance {
+
+    public interface UnderTest {
+        void method1();
+    }
+
+    public interface I3 {
+        void method3();
+    }
+
+    public interface I2 {
+        void method2();
+    }
+
+    public interface I4 {
+        void method4();
+    }
+
+    @ApplicationScoped
+    public static class C1 implements UnderTest {
+        @Inject
+        I2 i2;
+
+        @Inject
+        I3 i3;
+
+        @Inject
+        I4 i4;
+
+        @Override
+        public void method1() {
+            i2.method2();
+            i3.method3();
+        }
+    }
+
+    @ApplicationScoped
+    public static class C2 implements I2, I3 {
+        @Override
+        public void method2() {
+
+        }
+
+        @Override
+        public void method3() {
+
+        }
+    }
+
+    @ApplicationScoped
+    public static class C3 implements I4 {
+
+        @Override
+        public void method4() {
+
+        }
+    }
+}

integration-tests/injectmock/src/test/java/io/quarkus/it/mockbean/SameBeanInstanceTest.java

@@ -0,0 +1,35 @@
+package io.quarkus.it.mockbean;
+
+import static org.mockito.Mockito.*;
+
+import javax.inject.Inject;
+
+import org.junit.jupiter.api.Test;
+
+import io.quarkus.test.junit.QuarkusTest;
+import io.quarkus.test.junit.mockito.InjectMock;
+
+@QuarkusTest
+public class SameBeanInstanceTest {
+
+    @Inject
+    SameBeanInstance.UnderTest underTest;
+
+    @InjectMock
+    SameBeanInstance.I2 i2;
+
+    @InjectMock
+    SameBeanInstance.I3 i3;
+
+    @InjectMock
+    SameBeanInstance.I4 i4;
+
+    @Test
+    public void sample() {
+        underTest.method1();
+
+        verify(i2).method2();
+        verify(i3).method3();
+        verify(i4, never()).method4();
+    }
+}

test-framework/junit5-mockito/src/main/java/io/quarkus/test/junit/mockito/internal/CreateMockitoMocksCallback.java

@@ -4,6 +4,7 @@
 import java.lang.reflect.Field;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Optional;
 
 import javax.inject.Qualifier;
 
@@ -25,30 +26,45 @@ public void afterConstruct(Object testInstance) {
                 InjectMock injectMockAnnotation = field.getAnnotation(InjectMock.class);
                 if (injectMockAnnotation != null) {
                     Object beanInstance = getBeanInstance(testInstance, field, InjectMock.class);
-                    Object mock = createMockAndSetTestField(testInstance, field, beanInstance);
-                    MockitoMocksTracker.track(testInstance, mock, beanInstance);
+                    Optional<Object> result = createMockAndSetTestField(testInstance, field, beanInstance);
+                    if (result.isPresent()) {
+                        MockitoMocksTracker.track(testInstance, result.get(), beanInstance);
+                    }
                 }
             }
             current = current.getSuperclass();
         }
     }
 
-    private Object createMockAndSetTestField(Object testInstance, Field field, Object beanInstance) {
+    private Optional<Object> createMockAndSetTestField(Object testInstance, Field field, Object beanInstance) {
         Class<?> beanClass = beanInstance.getClass();
         // make sure we don't mock proxy classes, especially given that they don't have generics info
         if (ClientProxy.class.isAssignableFrom(beanClass)) {
             // and yet some of them appear to have Object as supertype, avoid them
             if (beanClass.getSuperclass() != Object.class)
                 beanClass = beanClass.getSuperclass();
         }
-        Object mock = Mockito.mock(beanClass);
+        Object mock;
+        boolean isNew;
+        Optional<Object> currentMock = MockitoMocksTracker.currentMock(testInstance, beanInstance);
+        if (currentMock.isPresent()) {
+            mock = currentMock.get();
+            isNew = false;
+        } else {
+            mock = Mockito.mock(beanClass);
+            isNew = true;
+        }
         field.setAccessible(true);
         try {
             field.set(testInstance, mock);
         } catch (IllegalAccessException e) {
             throw new RuntimeException(e);
         }
-        return mock;
+        if (isNew) {
+            return Optional.of(mock);
+        } else {
+            return Optional.empty();
+        }
     }
 
     static Object getBeanInstance(Object testInstance, Field field, Class<? extends Annotation> annotationType) {

test-framework/junit5-mockito/src/main/java/io/quarkus/test/junit/mockito/internal/MockitoMocksTracker.java

@@ -3,6 +3,7 @@
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.Map;
+import java.util.Optional;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 
@@ -27,6 +28,16 @@ static void reset(Object testInstance) {
         Mockito.reset(getMocks(testInstance).stream().map(o -> o.mock).toArray());
     }
 
+    static Optional<Object> currentMock(Object testInstance, Object beanInstance) {
+        Set<Mocked> mocks = getMocks(testInstance);
+        for (Mocked mocked : mocks) {
+            if (mocked.beanInstance == beanInstance) {
+                return Optional.of(mocked.mock);
+            }
+        }
+        return Optional.empty();
+    }
+
     static class Mocked {
         final Object mock;
         final Object beanInstance;