Issue #27365: Allow non-ascii in idlelib/NEWS.txt, for contributor names.

Rest of patch that should not be cherry picked into 3.5.2 final.

Lib/idlelib/aboutDialog.py

@@ -145,5 +145,7 @@ class AboutDialog(Toplevel):
         self.destroy()
 
 if __name__ == '__main__':
+    import unittest
+    unittest.main('idlelib.idle_test.test_helpabout', verbosity=2, exit=False)
     from idlelib.idle_test.htest import run
     run(AboutDialog)

Lib/idlelib/idle_test/test_help_about.py

@@ -0,0 +1,52 @@
+'''Test idlelib.help_about.
+
+Coverage:
+'''
+from idlelib import aboutDialog as help_about
+from idlelib import textView as textview
+from idlelib.idle_test.mock_idle import Func
+from idlelib.idle_test.mock_tk import Mbox
+import unittest
+
+About = help_about.AboutDialog
+class Dummy_about_dialog():
+    # Dummy class for testing file display functions.
+    idle_credits = About.ShowIDLECredits
+    idle_readme = About.ShowIDLEAbout
+    idle_news = About.ShowIDLENEWS
+    # Called by the above
+    display_file_text = About.display_file_text
+
+
+class DisplayFileTest(unittest.TestCase):
+    "Test that .txt files are found and properly decoded."
+    dialog = Dummy_about_dialog()
+
+    @classmethod
+    def setUpClass(cls):
+        cls.orig_mbox = textview.tkMessageBox
+        cls.orig_view = textview.view_text
+        cls.mbox = Mbox()
+        cls.view = Func()
+        textview.tkMessageBox = cls.mbox
+        textview.view_text = cls.view
+        cls.About = Dummy_about_dialog()
+
+    @classmethod
+    def tearDownClass(cls):
+        textview.tkMessageBox = cls.orig_mbox
+        textview.view_text = cls.orig_view
+
+    def test_file_isplay(self):
+        for handler in (self.dialog.idle_credits,
+                        self.dialog.idle_readme,
+                        self.dialog.idle_news):
+            self.mbox.showerror.message = ''
+            self.view.called = False
+            handler()
+            self.assertEqual(self.mbox.showerror.message, '')
+            self.assertEqual(self.view.called, True)
+
+
+if __name__ == '__main__':
+    unittest.main(verbosity=2)

Lib/idlelib/textView.py

@@ -76,6 +76,10 @@ def view_file(parent, title, filename, encoding=None, modal=True):
         tkMessageBox.showerror(title='File Load Error',
                                message='Unable to load file %r .' % filename,
                                parent=parent)
+    except UnicodeDecodeError as err:
+        tkMessageBox.showerror(title='Unicode Decode Error',
+                               message=str(err),
+                               parent=parent)
     else:
         return view_text(parent, title, contents, modal)