fixed PY-12920 **kwargs in constructor parameters disappear after "Add super class call" quick fix

python/src/com/jetbrains/python/inspections/quickfix/AddCallSuperQuickFix.java

@@ -24,6 +24,7 @@ import com.jetbrains.python.PyNames;
 import com.jetbrains.python.psi.*;
 import org.jetbrains.annotations.NonNls;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -139,7 +140,7 @@ public class AddCallSuperQuickFix implements LocalQuickFix {
   private static void addParametersFromSuper(@NotNull final PyFunction superInit, @NotNull final StringBuilder superCall,
                                              @NotNull final StringBuilder newFunction, boolean addComma,
                                              @NotNull final List<String> problemParams, @NotNull final List<String> functionParams,
-                                             String starName, String doubleStarName) {
+                                             @Nullable String starName, @Nullable String doubleStarName) {
     final PyParameterList paramList = superInit.getParameterList();
     PyParameter[] parameters = paramList.getParameters();
     boolean addDouble = false;
@@ -170,16 +171,20 @@ public class AddCallSuperQuickFix implements LocalQuickFix {
     }
     for(String p : problemParams)
       newFunction.append(",").append(p);
-    if (addStar) {
+    if (starName != null) {
       newFunction.append(",").append(starName);
-      if (addComma) superCall.append(",");
-      superCall.append(starName);
-      addComma = true;
+      if (addStar) {
+        if (addComma) superCall.append(",");
+        superCall.append(starName);
+        addComma = true;
+      }
     }
-    if (addDouble) {
-      if (addComma) superCall.append(",");
-      superCall.append(doubleStarName);
+    if (doubleStarName != null) {
       newFunction.append(",").append(doubleStarName);
+      if (addDouble) {
+        if (addComma) superCall.append(",");
+        superCall.append(doubleStarName);
+      }
     }
   }
 }

python/testData/quickFixes/AddCallSuperQuickFixTest/kwargs.py

@@ -0,0 +1,7 @@
+class A(object):
+    def __init__(self):
+        pass
+
+class B(A):
+    def <warning descr="Call to __init__ of super class is missed">__in<caret>it__</warning>(self, **kwargs):
+        pass

python/testData/quickFixes/AddCallSuperQuickFixTest/kwargs_after.py

@@ -0,0 +1,7 @@
+class A(object):
+    def __init__(self):
+        pass
+
+class B(A):
+    def __init__(self, **kwargs):
+        super(B, self).__init__()

python/testSrc/com/jetbrains/python/quickFixes/AddCallSuperQuickFixTest.java

@@ -30,4 +30,8 @@ public class AddCallSuperQuickFixTest extends PyQuickFixTestCase {
   public void testNewStyle() {
     doQuickFixTest(PyMissingConstructorInspection.class, PyBundle.message("QFIX.add.super"));
   }
+
+  public void testKwargs() {
+    doQuickFixTest(PyMissingConstructorInspection.class, PyBundle.message("QFIX.add.super"));
+  }
 }