Reviewers: mp+217067_code.launchpad.net,

Message:
Please take a look.

Description:
Check unicode support.

Ensure utf-8 is supported before starting
the Urwid interactive session.
This way we hope to avoid bad crashes
when the user has locale configuration problems.

Tests: `make check`.

QA:
If you have juju-quickstart installed, you should
be able to make it crash by overriding all the language
env vars, like the following:
`LC_ALL=C juju-quickstart -i`
You should see a UnicodeEncodeError:
'ascii' codec can't encode character u'\u2582' in position 0:
ordinal not in range(128)

With this branch, the following should instead work as usual:
`LC_ALL=C .venv/bin/python juju-quickstart -i`.

I am not sure how to make Urwid fail so that we can QA
the system exit in the code, but at least that code path
is tested.

https://code.launchpad.net/~frankban/juju-quickstart/check-locale/+merge/217067

(do not edit description out of merge proposal)


Please review this at https://codereview.appspot.com/90740043/

Affected files (+57, -0 lines):
   A [revision details]
   M quickstart/cli/base.py
   M quickstart/tests/cli/test_base.py


Index: [revision details]
=== added file '[revision details]'
--- [revision details]	2012-01-01 00:00:00 +0000
+++ [revision details]	2012-01-01 00:00:00 +0000
@@ -0,0 +1,2 @@
+Old revision: <email address hidden>
+New revision:  
<email address hidden>

Index: quickstart/cli/base.py
=== modified file 'quickstart/cli/base.py'
--- quickstart/cli/base.py	2014-01-03 10:22:24 +0000
+++ quickstart/cli/base.py	2014-04-24 14:47:18 +0000
@@ -26,6 +26,7 @@
  from __future__ import unicode_literals

  from collections import namedtuple
+import sys

  import urwid

@@ -44,6 +45,24 @@
  )


+def _check_encoding():
+    """Set the Urwid global byte encoding to utf-8.
+
+    Exit the application if, for some reasons, the change does not have  
effect.
+    """
+    urwid.set_encoding('utf-8')
+    if not urwid.supports_unicode():
+        # Note: the following message must only include ASCII characters.
+        msg = (
+            'Error: your terminal does not seem to support UTF-8  
encoding.\n'
+            'Please check your locale settings.\n'
+            'On Ubuntu, running the following might fix the problem:\n'
+            '  sudo locale-gen en_US.UTF-8\n'
+            '  sudo dpkg-reconfigure locales'
+        )
+        sys.exit(msg.encode('ascii'))
+
+
  class _MainLoop(urwid.MainLoop):
      """A customized Urwid loop.

@@ -109,6 +128,7 @@
            with the exit shortcut. See the quickstart.cli.views module  
docstring
            for more information about this functionality.
      """
+    _check_encoding()
      # Set up the application header.
      title = urwid.Text('\npreparing...')
      header_line = urwid.Divider('\N{LOWER ONE QUARTER BLOCK}')


Index: quickstart/tests/cli/test_base.py
=== modified file 'quickstart/tests/cli/test_base.py'
--- quickstart/tests/cli/test_base.py	2014-01-03 10:22:24 +0000
+++ quickstart/tests/cli/test_base.py	2014-04-24 14:49:16 +0000
@@ -18,14 +18,49 @@

  from __future__ import unicode_literals

+from contextlib import contextmanager
  import unittest

+import mock
  import urwid

  from quickstart.cli import base
  from quickstart.tests.cli import helpers as cli_helpers


+class TestCheckEncoding(unittest.TestCase):
+
+    @contextmanager
+    def patch_urwid(self, supports_unicode=True):
+        """Patch the urwid.set_encoding and urwid.supports_unicode calls.
+
+        Ensure the mock functions are called once with the expected  
arguments.
+
+        Make urwid.supports_unicode return the given supports_unicode  
value.
+        """
+        mock_supports_unicode = mock.Mock(return_value=supports_unicode)
+        with mock.patch('urwid.set_encoding') as mock_set_encoding:
+            with mock.patch('urwid.supports_unicode',  
mock_supports_unicode):
+                yield
+        mock_set_encoding.assert_called_once_with('utf-8')
+        mock_supports_unicode.assert_called_once_with()
+
+    def test_unicode_supported(self):
+        # The utf-8 encoding is properly set and the function exits without
+        # errors.
+        with self.patch_urwid(supports_unicode=True):
+            base._check_encoding()
+
+    def test_unicode_not_supported(self):
+        # If unicode is not supported, the program exits with an error.
+        with self.patch_urwid(supports_unicode=False):
+            with self.assertRaises(SystemExit) as context_manager:
+                base._check_encoding()
+        self.assertIn(
+            b'Error: your terminal does not seem to support UTF-8  
encoding.',
+            bytes(context_manager.exception))
+
+
  class TestMainLoop(unittest.TestCase):

      def setUp(self):