'Test _find_mako_expressions for unparseable expressions'

@data({'template': '    ${{unparseable}    ${}', 'start_index': 1}, {'template': "    ${'unparseable}    ${}", 'start_index': 1})
def test_find_unparseable_mako_expressions(self, data):

    linter = MakoTemplateLinter()
    expressions = linter._find_mako_expressions(data['template'])
    self.assertTrue((2 <= len(expressions)))
    self.assertEqual(expressions[0].start_index, data['start_index'])
    self.assertIsNone(expressions[0].expression)
