PY-19137: Move object to parent in superclass extracting even for Py3K if class explicitly extends object

python/src/com/jetbrains/python/refactoring/classes/extractSuperclass/PyExtractSuperclassHelper.java

@@ -44,6 +44,7 @@ import org.jetbrains.annotations.Nullable;
 
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 
@@ -79,7 +80,7 @@ public final class PyExtractSuperclassHelper {
 
     // PY-12171
     final PyMemberInfo<PyElement> objectMember = MembersManager.findMember(selectedMemberInfos, ALLOW_OBJECT);
-    if (LanguageLevel.forElement(clazz).isPy3K()) {
+    if (LanguageLevel.forElement(clazz).isPy3K() && !isObjectParentDeclaredExplicitly(clazz)) {
       // Remove object from list if Py3
       if (objectMember != null) {
         selectedMemberInfos.remove(objectMember);
@@ -110,7 +111,13 @@ public final class PyExtractSuperclassHelper {
     afterData.addElement(newClass);
     project.getMessageBus().syncPublisher(RefactoringEventListener.REFACTORING_EVENT_TOPIC)
       .refactoringDone(getRefactoringId(), afterData);
+  }
 
+  /**
+   * If class explicitly extends object we shall move it even in Py3K
+   */
+  private static boolean isObjectParentDeclaredExplicitly(@NotNull final PyClass clazz) {
+    return Arrays.stream(clazz.getSuperClassExpressions()).filter(o -> PyNames.OBJECT.equals(o.getName())).findFirst().isPresent();
   }
 
   private static PyClass placeNewClass(final Project project, PyClass newClass, @NotNull final PyClass clazz, final String targetFile) {

python/testData/refactoring/extractsuperclass/py3ParentHasObject.after.py

@@ -0,0 +1,7 @@
+class Parent(object):
+    def spam(self):
+        pass
+
+
+class Child(Parent):
+    pass

python/testData/refactoring/extractsuperclass/py3ParentHasObject.before.py

@@ -0,0 +1,3 @@
+class Child(object):
+    def spam(self):
+        pass

python/testSrc/com/jetbrains/python/refactoring/classes/extractSuperclass/PyExtractSuperclassTest.java

@@ -44,6 +44,12 @@ public class PyExtractSuperclassTest extends PyClassRefactoringTest {
     super("extractsuperclass");
   }
 
+  // Checks if class explicitly extends object we shall move it even in Py3K (PY-19137)
+  public void testPy3ParentHasObject() throws Exception {
+    setLanguageLevel(LanguageLevel.PYTHON30);
+    doSimpleTest("Child", "Parent", null, true, false, ".spam");
+  }
+
   // Checks that moving methods between files moves imports as well
   public void testImportMultiFile() throws Throwable {
     multiFileTestHelper(".do_useful_stuff", false);