From 7f7b9d8a9f0194c609a902167d90b7bf9f3639c7 Mon Sep 17 00:00:00 2001
From: Dmitry Jemerov <yole@jetbrains.com>
Date: Mon, 5 Sep 2011 16:47:09 +0200
Subject: [PATCH] SIOOBE (PY-4455)

---
 .../python/refactoring/PyRefactoringUtil.java      |  3 +++
 .../introduceVariable/incorrectSelection.py        |  1 +
 .../refactoring/PyIntroduceVariableTest.java       | 14 ++++++++++++++
 3 files changed, 18 insertions(+)
 create mode 100644 python/testData/refactoring/introduceVariable/incorrectSelection.py

diff --git a/python/src/com/jetbrains/python/refactoring/PyRefactoringUtil.java b/python/src/com/jetbrains/python/refactoring/PyRefactoringUtil.java
index 222d4975399c..d392eb8adb91 100644
--- a/python/src/com/jetbrains/python/refactoring/PyRefactoringUtil.java
+++ b/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);
diff --git a/python/testData/refactoring/introduceVariable/incorrectSelection.py b/python/testData/refactoring/introduceVariable/incorrectSelection.py
new file mode 100644
index 000000000000..2d00015f734b
--- /dev/null
+++ b/python/testData/refactoring/introduceVariable/incorrectSelection.py
@@ -0,0 +1 @@
+a = <selection>b + fu</selection>nc()
diff --git a/python/testSrc/com/jetbrains/python/refactoring/PyIntroduceVariableTest.java b/python/testSrc/com/jetbrains/python/refactoring/PyIntroduceVariableTest.java
index c97c7b6682aa..c866b98a6cfb 100644
--- a/python/testSrc/com/jetbrains/python/refactoring/PyIntroduceVariableTest.java
+++ b/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() {