'Make sure the required fields are in the header, according to:
http://www.gnu.org/software/gettext/manual/gettext.html#Header-Entry'

def test_header(self):

    with temp_cwd(None) as cwd:
        assert_python_ok(self.script)
        with open('messages.pot') as fp:
            data = fp.read()
        header = self.get_header(data)
        self.assertIn('Project-Id-Version', header)
        self.assertIn('POT-Creation-Date', header)
        self.assertIn('PO-Revision-Date', header)
        self.assertIn('Last-Translator', header)
        self.assertIn('Language-Team', header)
        self.assertIn('MIME-Version', header)
        self.assertIn('Content-Type', header)
        self.assertIn('Content-Transfer-Encoding', header)
        self.assertIn('Generated-By', header)
