diff -r 58674a027d10 Lib/idlelib/GrepDialog.py
--- a/Lib/idlelib/GrepDialog.py	Wed Jan 07 23:49:06 2015 -0500
+++ b/Lib/idlelib/GrepDialog.py	Fri Jan 09 19:13:15 2015 +1100
@@ -105,32 +105,32 @@
             # so in OW.write, OW.text.insert fails.
             pass
 
-    def findfiles(self, dir, base, rec):
-        try:
-            names = os.listdir(dir or os.curdir)
-        except OSError as msg:
-            print(msg)
-            return []
-        list = []
-        subdirs = []
-        for name in names:
-            fn = os.path.join(dir, name)
-            if os.path.isdir(fn):
-                subdirs.append(fn)
-            else:
-                if fnmatch.fnmatch(name, base):
-                    list.append(fn)
-        if rec:
-            for subdir in subdirs:
-                list.extend(self.findfiles(subdir, base, rec))
-        return list
-
     def close(self, event=None):
         if self.top:
             self.top.grab_release()
             self.top.withdraw()
 
 
+def findfiles(folder=os.curdir, pattern='*', recursive=True):
+    """
+    A generator that returns matching file names.
+
+    Keyword arguments:
+    folder -- the folder to search (default '.')
+    pattern -- the filename pattern to match (default '*')
+    recursive -- if True, recursively search subfolders (default True)
+    """
+    try:
+        for dirpath, dirnames, filenames in os.walk(folder or os.curdir):
+            for name in filenames:
+                if fnmatch.fnmatch(name, pattern):
+                    yield os.path.join(dirpath, name)
+            if not recursive:
+                break
+    except OSError as msg:
+        print(msg)
+
+
 def _grep_dialog(parent):  # htest #
     from idlelib.PyShell import PyShellFileList
     root = Tk()
diff -r 58674a027d10 Lib/idlelib/idle_test/test_grep.py
--- a/Lib/idlelib/idle_test/test_grep.py	Wed Jan 07 23:49:06 2015 -0500
+++ b/Lib/idlelib/idle_test/test_grep.py	Fri Jan 09 19:13:15 2015 +1100
@@ -10,6 +10,8 @@
 from idlelib.idle_test.mock_tk import Var
 from idlelib.GrepDialog import GrepDialog
 import re
+import os
+import idlelib.GrepDialog as GrepDialog_module
 
 class Dummy_searchengine:
     '''GrepDialog.__init__ calls parent SearchDiabolBase which attaches the
@@ -25,7 +27,6 @@
     # Methods tested
     #default_command = GrepDialog.default_command
     grep_it = GrepDialog.grep_it
-    findfiles = GrepDialog.findfiles
     # Other stuff needed
     recvar = Var(False)
     engine = searchengine
@@ -35,11 +36,39 @@
 grep = Dummy_grep()
 
 class FindfilesTest(unittest.TestCase):
-    # findfiles is really a function, not a method, could be iterator
     # test that filename return filename
     # test that idlelib has many .py files
     # test that recursive flag adds idle_test .py files
-    pass
+    def test_findfiles(self):
+        old_cwd = os.getcwd()
+        # change cwd to test_grep.py's folder
+        os.chdir(os.path.dirname(os.path.realpath(__file__)))
+
+        # check if test_grep.py can be found
+        for dir_contents in (GrepDialog_module.findfiles(),
+                             GrepDialog_module.findfiles(os.curdir),
+                             GrepDialog_module.findfiles(os.curdir, '*'),
+                             GrepDialog_module.findfiles(os.curdir, '*.py'),
+                             GrepDialog_module.findfiles(os.curdir, '*.py', True),
+                             GrepDialog_module.findfiles(os.curdir, '*.py', False),):
+            self.assertIn(os.path.join(os.curdir, 'test_grep.py'), dir_contents)
+
+        # check if specifying the parent folder works
+        grep_dialog_file = os.path.join(os.pardir, 'GrepDialog.py')
+        parent_contents = GrepDialog_module.findfiles(os.pardir, '*', False)
+        self.assertIn(grep_dialog_file, parent_contents)
+
+        # check that recursive=False works
+        has_recursed = any([name for name in parent_contents if 'idle_test' in name])
+        self.assertFalse(has_recursed)
+
+        # check if recursion works
+        test_grep_file = os.path.join(os.pardir, 'idle_test', 'test_grep.py')
+        parent_contents_rec = GrepDialog_module.findfiles(os.pardir, '*', True)
+        self.assertIn(test_grep_file, parent_contents_rec)
+
+        # restore old cwd
+        os.chdir(old_cwd)
 
 class Grep_itTest(unittest.TestCase):
     # Test captured reports with 0 and some hits.