SIOOBE (PY-4455)

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

@@ -83,6 +83,9 @@ public class PyRefactoringUtil {
       }
       final String parentText = parent.getText();
       final int startOffset = element1.getTextOffset() - parent.getTextOffset() - 1;
+      if (startOffset < 0) {
+        return null;
+      }
       final int endOffset = element2.getTextOffset() + element2.getTextLength() - parent.getTextOffset();
 
       final String prefix = parentText.substring(0, startOffset);

python/testData/refactoring/introduceVariable/incorrectSelection.py

@@ -0,0 +1 @@
+a = <selection>b + fu</selection>nc()

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

@@ -1,5 +1,6 @@
 package com.jetbrains.python.refactoring;
 
+import com.intellij.refactoring.util.CommonRefactoringUtil;
 import com.intellij.testFramework.TestDataPath;
 import com.jetbrains.python.psi.PyCallExpression;
 import com.jetbrains.python.psi.PyExpression;
@@ -42,6 +43,19 @@ public class PyIntroduceVariableTest extends PyIntroduceTestCase {
   public void testSuggestStringConstantValue() { // PY-1276
     doTestSuggestions(PyExpression.class, "foo_bar");
   }
+  
+  public void testIncorrectSelection() {  // PY-4455
+    boolean thrownExpectedException = false;
+    try {
+      doTest();
+    }
+    catch (CommonRefactoringUtil.RefactoringErrorHintException e) {
+      if (e.getMessage().equals("Cannot perform refactoring using selected element(s)")) {
+        thrownExpectedException = true;
+      }
+    }
+    assertTrue(thrownExpectedException);
+  }
 
   @Override
   protected String getTestDataPath() {