don't suggest any used names as name candidates for introduce variable (PY-4605)

python/src/com/jetbrains/python/refactoring/PyRefactoringUtil.java

@@ -104,7 +104,7 @@ public class PyRefactoringUtil {
   }
 
   @NotNull
-  public static Collection<String> collectScopeVariables(@Nullable final PsiElement scope) {
+  public static Collection<String> collectUsedNames(@Nullable final PsiElement scope) {
     if (!(scope instanceof PyClass) && !(scope instanceof PyFile) && !(scope instanceof PyFunction)) {
       return Collections.emptyList();
     }
@@ -121,18 +121,18 @@ public class PyRefactoringUtil {
       }
 
       @Override
-      public void visitPyStatement(@NotNull final PyStatement node) {
-        if ((node instanceof PyAssignmentStatement) || (scope instanceof PyFunction)) {
-          node.acceptChildren(this);
-        }
+      public void visitPyReferenceExpression(PyReferenceExpression node) {
+        variables.add(node.getReferencedName());
       }
 
       @Override
       public void visitPyFunction(@NotNull final PyFunction node) {
+        variables.add(node.getName());
       }
 
       @Override
       public void visitPyClass(@NotNull final PyClass node) {
+        variables.add(node.getName());
       }
     });
     return variables;

python/src/com/jetbrains/python/refactoring/introduce/IntroduceValidator.java

@@ -51,6 +51,6 @@ public abstract class IntroduceValidator {
       context = psiElement.getContainingFile();
     }
 
-    return PyRefactoringUtil.collectScopeVariables(context).contains(name);
+    return PyRefactoringUtil.collectUsedNames(context).contains(name);
   }
 }

python/testData/refactoring/introduceVariable/suggestNamesNotInScope.py

@@ -0,0 +1,2 @@
+if myfu<caret>nc() == 3:
+    pass

python/testSrc/com/jetbrains/python/refactoring/PyIntroduceVariableTest.java

@@ -52,6 +52,12 @@ public class PyIntroduceVariableTest extends PyIntroduceTestCase {
     assertFalse(strings.contains("str"));
   }
   
+  public void testSuggestNamesNotInScope() {  // PY-4605
+    final Collection<String> strings = buildSuggestions(PyExpression.class);
+    assertTrue(strings.contains("myfunc1"));
+    assertFalse(strings.contains("myfunc"));
+  }
+
   public void testIncorrectSelection() {  // PY-4455
     doTestCannotPerform();
   }