diff -r 1589203ff116 Lib/idlelib/SearchEngine.py
--- a/Lib/idlelib/SearchEngine.py	Sat Aug 24 15:15:19 2013 -0500
+++ b/Lib/idlelib/SearchEngine.py	Sat Aug 24 22:00:03 2013 -0400
@@ -1,6 +1,6 @@
 '''Define SearchEngine for search dialogs.'''
 import re
-from tkinter import *
+from tkinter import StringVar, BooleanVar, TclError
 import tkinter.messagebox as tkMessageBox
 
 def get(root):
@@ -22,14 +22,13 @@
 
         The dialogs bind these to the UI elements present in the dialogs.
         '''
-        self.root = root
-        self.patvar = StringVar(root)           # search pattern
-        self.revar = BooleanVar(root)           # regular expression?
-        self.casevar = BooleanVar(root)         # match case?
-        self.wordvar = BooleanVar(root)         # match whole word?
-        self.wrapvar = BooleanVar(root)         # wrap around buffer?
-        self.wrapvar.set(1)                     # (on by default)
-        self.backvar = BooleanVar(root)         # search backwards?
+        self.root = root  # need for report_error()
+        self.patvar = StringVar(root, '')   # search pattern
+        self.revar = BooleanVar(root, False)   # regular expression?
+        self.casevar = BooleanVar(root, False)   # match case?
+        self.wordvar = BooleanVar(root, False)   # match whole word?
+        self.wrapvar = BooleanVar(root, True)   # wrap around buffer?
+        self.backvar = BooleanVar(root, False)   # search backwards?
 
     # Access methods
 
@@ -56,9 +55,16 @@
 
     # Higher level access methods
 
+    def setcookedpat(self, pat):
+        "Set pattern after escaping if re."
+        # called only in SearchDialog.py: 66
+        if self.isre():
+            pat = re.escape(pat)
+        self.setpat(pat)
+
     def getcookedpat(self):
         pat = self.getpat()
-        if not self.isre():
+        if not self.isre():  # if True, see setcookedpat
             pat = re.escape(pat)
         if self.isword():
             pat = r"\b%s\b" % pat
@@ -90,17 +96,12 @@
         # Derived class could override this with something fancier
         msg = "Error: " + str(msg)
         if pat:
-            msg = msg + "\np\Pattern: " + str(pat)
+            msg = msg + "\nPattern: " + str(pat)
         if col >= 0:
             msg = msg + "\nOffset: " + str(col)
         tkMessageBox.showerror("Regular expression error",
                                msg, master=self.root)
 
-    def setcookedpat(self, pat):
-        if self.isre():
-            pat = re.escape(pat)
-        self.setpat(pat)
-
     def search_text(self, text, prog=None, ok=0):
         '''Return (lineno, matchobj) for prog in text widget, or None.
 
@@ -188,15 +189,18 @@
         return None
 
 def search_reverse(prog, chars, col):
-    '''Search backwards in a string (line of text).
+    '''Search backwards and return an re match object or None.
 
     This is done by searching forwards until there is no match.
+    Prog: compiled re object with a search method returning a match.
+    Chars: line of text, without \n.
+    Col: stop index for the search; the limit for match.end().
     '''
     m = prog.search(chars)
     if not m:
         return None
     found = None
-    i, j = m.span()
+    i, j = m.span()  # m.start(), m.end() == match slice indexes
     while i < col and j <= col:
         found = m
         if i == j:
@@ -226,7 +230,7 @@
     line, col = map(int, index.split(".")) # Fails on invalid index
     return line, col
 
-##if __name__ == "__main__":
-##    from test import support; support.use_resources = ['gui']
-##    import unittest
-##    unittest.main('idlelib.idle_test.test_searchengine', verbosity=2, exit=False)
+if __name__ == "__main__":
+    from test import support; support.use_resources = ['gui']
+    import unittest
+    unittest.main('idlelib.idle_test.test_searchengine', verbosity=2, exit=False)
diff -r 1589203ff116 Lib/idlelib/idle_test/test_searchengine.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Lib/idlelib/idle_test/test_searchengine.py	Sat Aug 24 22:00:03 2013 -0400
@@ -0,0 +1,359 @@
+import re
+import unittest
+from test.support import requires
+from tkinter import Tk, Text, BooleanVar, StringVar
+import tkinter.messagebox as tkMessageBox
+from idlelib import SearchEngine as se
+from idlelib.idle_test.mock_tk import Var, Mbox
+
+def setUpModule():
+    se.BooleanVar = Var
+    se.StringVar = Var
+    se.tkMessageBox = Mbox
+
+def tearDownModule():
+    se.BooleanVar = BooleanVar
+    se.StringVar = StringVar
+    se.tkMessageBox = tkMessageBox
+
+
+class Mock:
+    def __init__(self, *args, **kwargs): pass
+
+class GetTest(unittest.TestCase):
+    # SearchEngine.get returns singleton created & saved on first call.
+    def test_get(self):
+        saved_Engine = se.SearchEngine
+        se.SearchEngine = Mock  # monkey-patch
+        try:
+            root = Mock()
+            engine = se.get(root)
+            self.assertIsInstance(engine, se.SearchEngine)
+            self.assertIs(root._searchengine, engine)
+            self.assertIs(se.get(root), engine)
+        finally:
+            se.SearchEngine = saved_Engine
+
+class GetLineColTest(unittest.TestCase):
+    #  simple text-independent helper function, could be inlined
+    def test_get_line_col(self):
+        self.assertEqual(se.get_line_col('1.0'), (1, 0))
+        self.assertEqual(se.get_line_col('1.11'), (1, 11))
+
+        self.assertRaises(ValueError, se.get_line_col, ('1.0 lineend'))
+        self.assertRaises(ValueError, se.get_line_col, ('end'))
+
+class GetSelectionTest(unittest.TestCase):
+    # text-dependent helper function
+    # need tkinter.Text until upgrade mock Text
+    @classmethod
+    def setUpClass(cls):
+        requires('gui')
+        cls.root = Tk()
+
+    @classmethod
+    def tearDownClass(cls):
+        cls.root.destroy()
+
+    def test_get_selection(self):
+        text = Text(master=self.root)
+        text.insert('1.0', 'hello world')
+        # Test with 'Hello' selected
+        text.tag_add('sel', '1.0', '1.5')
+        self.assertEqual(se.get_selection(text), ('1.0', '1.5'))
+        # Test with ' world' selected
+        text.tag_remove('sel', '1.0', 'end')
+        text.tag_add('sel', '1.6', '1.end')
+        self.assertEqual(se.get_selection(text), ('1.6', '1.11'))
+
+    def test_get_mark(self):
+        text = Text(master=self.root)
+        text.insert('1.0', 'hello world')
+        # Test with no selection and cursor at 1.0
+        text.mark_set('insert', '1.0')
+        self.assertEqual(se.get_selection(text), ('1.0', '1.0'))
+        # Test with no selection and cursor at 1.8
+        text.mark_set('insert', '1.8')
+        self.assertEqual(se.get_selection(text), ('1.8', '1.8'))
+
+
+class SearchReverseTest(unittest.TestCase):
+
+    def test_search_reverse(self):
+        Equal = self.assertEqual
+        line = "Here is an 'is' test text."
+        prog = re.compile('is')
+        Equal(se.search_reverse(prog, line, len(line)).span(), (12, 14))
+        Equal(se.search_reverse(prog, line, 14).span(), (12, 14))
+        Equal(se.search_reverse(prog, line, 13).span(), (5, 7))
+        Equal(se.search_reverse(prog, line, 7).span(), (5, 7))
+        Equal(se.search_reverse(prog, line, 6), None)
+
+
+class SearchEngineTest(unittest.TestCase):
+    # test non-text methods of class
+
+    @classmethod
+    def setUpClass(cls):
+        cls.root = None
+        cls.engine = se.SearchEngine(cls.root)
+
+    def setUp(self):
+        self.engine.__init__(self.root)
+
+    def test_is_get(self):
+        engine = self.engine
+        Equal = self.assertEqual
+
+        Equal(engine.getpat(), '')
+        engine.setpat('hello')
+        Equal(engine.getpat(), 'hello')
+
+        Equal(engine.isre(), False)
+        engine.revar.set(1)
+        Equal(engine.isre(), True)
+
+        Equal(engine.iscase(), False)
+        engine.casevar.set(1)
+        Equal(engine.iscase(), True)
+
+        Equal(engine.isword(), False)
+        engine.wordvar.set(1)
+        Equal(engine.isword(), True)
+
+        Equal(engine.iswrap(), True)
+        engine.wrapvar.set(0)
+        Equal(engine.iswrap(), False)
+
+        Equal(engine.isback(), False)
+        engine.backvar.set(1)
+        Equal(engine.isback(), True)
+
+    def test_setcookedpat(self):
+        engine = self.engine
+        engine.setcookedpat('\s')
+        self.assertEqual(engine.getpat(), '\s')
+        engine.revar.set(1)
+        engine.setcookedpat('\s')
+        self.assertEqual(engine.getpat(), r'\\s')
+
+    def test_getcookedpat(self):
+        engine = self.engine
+        Equal = self.assertEqual
+
+        Equal(engine.getcookedpat(), '')
+        engine.setpat('hello')
+        Equal(engine.getcookedpat(), 'hello')
+        engine.wordvar.set(True)
+        Equal(engine.getcookedpat(), r'\bhello\b')
+        engine.wordvar.set(False)
+
+        engine.setpat('\s')
+        Equal(engine.getcookedpat(), r'\\s')
+        engine.revar.set(True)
+        Equal(engine.getcookedpat(), '\s')
+
+    def test_getprog(self):
+        engine = self.engine
+        Equal = self.assertEqual
+
+        engine.setpat('Hello')
+        temppat = engine.getprog()
+        Equal(temppat.pattern, re.compile('Hello', re.IGNORECASE).pattern)
+        engine.casevar.set(1)
+        temppat = engine.getprog()
+        Equal(temppat.pattern, re.compile('Hello').pattern, 0)
+
+        engine.setpat('')
+        Equal(engine.getprog(), None)
+        engine.setpat('+')
+        engine.revar.set(1)
+        Equal(engine.getprog(), None)
+        self.assertEqual(Mbox.showerror.message,
+                          'Error: nothing to repeat\nPattern: +')
+
+    def test_report_error(self):
+        showerror = Mbox.showerror
+        Equal = self.assertEqual
+        pat = '[a-z'
+        msg = 'unexpected end of regular expression'
+
+        Equal(self.engine.report_error(pat, msg), None)
+        Equal(showerror.title, 'Regular expression error')
+        expected_message = ("Error: " + msg + "\nPattern: [a-z")
+        Equal(showerror.message, expected_message)
+
+        Equal(self.engine.report_error(pat, msg, 5), None)
+        Equal(showerror.title, 'Regular expression error')
+        expected_message += "\nOffset: 5"
+        Equal(showerror.message, expected_message)
+
+
+class SearchMethodTest(unittest.TestCase):
+
+    @classmethod
+    def setUpClass(cls):
+        requires('gui')
+        cls.root = Tk()
+        cls.engine = se.SearchEngine(cls.root)
+        cls.text = Text(master=cls.root)
+
+    @classmethod
+    def tearDownClass(cls):
+        cls.root.destroy()
+
+    def setUp(self):
+        self.text.delete('1.0', 'end')
+
+    def test_search_text(self):
+        engine = self.engine
+        engine.setpat('')
+        self.assertIsNone(engine.search_text(self.text, ''))
+        
+        testtext = (
+            "from string import Template\n"
+            "s = Template('$who likes $what')\n"
+            "s.substitute(who='tim', what='kung pao')\n"
+            "d = dict(who='tim')\n"
+            "Template('Give $who $100').substitute(d)\n"
+            "Template('$who likes $what').substitute(d)\n"
+            "Template('$who likes $what').safe_substitute(d)\n")
+
+        self.text.insert('1.0', testtext)
+        pat = re.compile("substitute")
+
+        # Search forward from cursor at 1.0
+        self.text.mark_set('insert', '1.0')
+        searchresult = engine.search_text(self.text, pat)
+        # searchresult is a tuple in the form (lineno, matchobject)
+        self.assertEqual(searchresult[0], 3)            # test line match
+        self.assertEqual(searchresult[1].span()[0], 2)  # test column match
+
+        # Test that search wraps around to beginning of text
+        self.text.mark_set('insert', '7.38')
+        searchresult = engine.search_text(self.text, pat)
+        self.assertEqual(searchresult[0], 3)
+        self.assertEqual(searchresult[1].span()[0], 2)
+
+        # Test that search doesn't wrap forward when wrapvar set to 0
+        engine.wrapvar.set(0)
+        self.text.mark_set('insert', '7.38')
+        searchresult = engine.search_text(self.text, pat)
+        self.assertEqual(searchresult, None)
+
+        # Test that search doesn't wrap in reverse when wrapvar set to 0
+        engine.backvar.set(1)
+        self.text.mark_set('insert', '2.4')
+        searchresult = engine.search_text(self.text, pat)
+        self.assertEqual(searchresult, None)
+        engine.wrapvar.set(1)
+
+        # Test that search reverses when backvar is set to 1
+        self.text.mark_set('insert', '6.5')
+        searchresult = engine.search_text(self.text, pat)
+        self.assertEqual(searchresult[0], 5)
+        self.assertEqual(searchresult[1].span()[0], 27)
+
+        # Test that search wraps around backwards to end of text
+        self.text.mark_set('insert', '1.5')
+        searchresult = engine.search_text(self.text, pat)
+        self.assertEqual(searchresult[0], 7)
+        self.assertEqual(searchresult[1].span()[0], 34)
+        engine.backvar.set(0)
+
+        # Test empty match with 'ok' flag set and 'string' on line 1 selected
+        self.text.tag_add('sel', '1.5', '1.11')
+        engine.backvar.set(0)
+        pat = re.compile("\w+")
+        searchresult = engine.search_text(self.text, pat, 1)
+        self.assertEqual(searchresult[0], 1)
+        self.assertEqual(searchresult[1].span()[0], 5)
+
+        # Test match with 'ok' flag not set and 'string' selected
+        searchresult = engine.search_text(self.text, pat, 0)
+        self.assertEqual(searchresult[0], 1)
+        self.assertEqual(searchresult[1].span()[0], 12)
+
+    def test_search_forward(self):
+        engine = self.engine
+        testtext = (
+            "from string import Template\n"
+            "s = Template('$who likes $what')\n"
+            "s.substitute(who='tim', what='kung pao')\n"
+            "d = dict(who='tim')\n"
+            "Template('Give $who $100').substitute(d)\n"
+            "Template('$who likes $what').substitute(d)\n"
+            "Template('$who likes $what').safe_substitute(d)\n")
+
+        self.text.insert('1.0', testtext)
+        pat = re.compile("substitute")
+
+        # Search forward from cursor at 1.0
+        searchresult = engine.search_forward(self.text, pat, 1, 0, True)
+        self.assertEqual(searchresult[0], 3)            # test line match
+        self.assertEqual(searchresult[1].span()[0], 2)  # test column match
+
+        # Test that search wraps around to beginning of text
+        searchresult = engine.search_forward(self.text, pat, 7, 38, True)
+        self.assertEqual(searchresult[0], 3)
+        self.assertEqual(searchresult[1].span()[0], 2)
+
+        # Test that search doesn't wrap forward when wrapvar set to 0
+        searchresult = engine.search_forward(self.text, pat, 7, 38, False)
+        self.assertEqual(searchresult, None)
+
+        # Test empty match with 'ok' flag set and 'string' on line 1 selected
+        pat = re.compile("\w+")
+        searchresult = engine.search_forward(self.text, pat, 1, 5, 1, 1)
+        self.assertEqual(searchresult[0], 1)
+        self.assertEqual(searchresult[1].span()[0], 5)
+
+        # Test empty match with 'ok' flag not set and 'string' selected
+        searchresult = engine.search_forward(self.text, pat, 1, 11, 1)
+        self.assertEqual(searchresult[0], 1)
+        self.assertEqual(searchresult[1].span()[0], 12)
+
+    def test_search_backward(self):
+        engine = self.engine
+        testtext = (
+            "from string import Template\n"
+            "s = Template('$who likes $what')\n"
+            "s.substitute(who='tim', what='kung pao')\n"
+            "d = dict(who='tim')\n"
+            "Template('Give $who $100').substitute(d)\n"
+            "Template('$who likes $what').substitute(d)\n"
+            "Template('$who likes $what').safe_substitute(d)\n")
+
+        self.text.insert('1.0', testtext)
+        pat = re.compile("substitute")
+
+        # Test that search doesn't wrap in reverse when wrapvar set to 0
+        searchresult = engine.search_backward(self.text, pat, 2, 4, 0)
+        self.assertEqual(searchresult, None)
+
+        # Test that search reverses when backvar is set to 1
+        self.text.mark_set('insert', '6.5')
+        searchresult = engine.search_backward(self.text, pat, 6, 5, 1)
+        self.assertEqual(searchresult[0], 5)
+        self.assertEqual(searchresult[1].span()[0], 27)
+
+        # Test that search wraps around backwards to end of text
+        searchresult = engine.search_backward(self.text, pat, 1, 5, 1)
+        self.assertEqual(searchresult[0], 7)
+        self.assertEqual(searchresult[1].span()[0], 34)
+        engine.backvar.set(0)
+
+        # Test empty match with 'ok' flag set
+        pat = re.compile("\w+")
+        searchresult = engine.search_backward(self.text, pat, 1, 11, 1, 1)
+        self.assertEqual(searchresult[0], 1)
+        self.assertEqual(searchresult[1].span()[0], 5)
+
+        # Test empty match with 'ok' flag not set
+        searchresult = engine.search_backward(self.text, pat, 1, 5, 1, 0)
+        self.assertEqual(searchresult[0], 1)
+        self.assertEqual(searchresult[1].span()[0], 0)
+
+
+if __name__ == '__main__':
+    unittest.main(verbosity=2, exit=2)