push down: fix extends/implements chooser (IDEA-190409)

java/java-impl/src/com/intellij/refactoring/memberPushDown/JavaPushDownDelegate.java

@@ -41,7 +41,6 @@ import com.intellij.refactoring.util.DocCommentPolicy;
 import com.intellij.refactoring.util.RefactoringUtil;
 import com.intellij.refactoring.util.classMembers.MemberInfo;
 import com.intellij.util.IncorrectOperationException;
-import java.util.HashSet;
 import com.intellij.util.containers.MultiMap;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
@@ -291,7 +290,7 @@ public class JavaPushDownDelegate extends PushDownDelegate<MemberInfo, PsiMember
               }
             }
             PsiJavaCodeReferenceElement classRef = classType != null ? factory.createReferenceElementByType(classType) : factory.createClassReferenceElement(psiClass);
-            if (psiClass.isInterface()) {
+            if (psiClass.isInterface() && !targetClass.isInterface()) {
               targetClass.getImplementsList().add(classRef);
             } else {
               targetClass.getExtendsList().add(classRef);

java/java-tests/testData/refactoring/pushDown/InterfaceExtends.java

@@ -0,0 +1,5 @@
+interface A {}
+
+interface Test extends A { }
+
+interface B extends Test { }

java/java-tests/testData/refactoring/pushDown/InterfaceExtends_after.java

@@ -0,0 +1,5 @@
+interface A {}
+
+interface Test extends A { }
+
+interface B extends Test, A { }

java/java-tests/testSrc/com/intellij/java/refactoring/PushDownTest.java

@@ -58,6 +58,7 @@ public class PushDownTest extends LightRefactoringTestCase {
   public void testOverridingMethodWithSubst() { doTest(); }
   public void testSameClassInterface() { doTestImplements(); }
   public void testPreserveTypeArgs() { doTestImplements(); }
+  public void testInterfaceExtends() { doTestImplements(); }
   public void testSubstTypeArgs() { doTestImplements(); }
   public void testExtensionMethodToInterface() { doTest(); }
   public void testExtensionMethodToClass() { doTest(); }