jinjatestcase.py

from collections import Mapping
import unittest
import warnings

from flask import get_template_attribute

from myapplication import app


class JinjaTestCase(unittest.TestCase):
    """Base/mixin class for tests that may refer to Jinja templates
    and symbols defined therin (mostly macros).

    Usage::

        class Hello(JinjaTestCase):
            __template_imports__ = {
                'hello': 'hello.html',  # import 'hello' macro as 'hello' attr.
            }

            def test_hello(self):
                self.assert_equal("Hello, world!", self.hello())
    """
    class __metaclass__(type):
        """Metaclass for importing Jinja symbols as class attributes."""

        def __new__(cls, cls_name, bases, dict_):
            """Create test case class, resolving ``__template_imports__``
            specifications into Jinja template imports.
            """
            imports = dict_.get('__template_imports__', {})
            if isinstance(imports, Mapping):
                imports = imports.items()

            for name, template in imports:
                if name in dict_:
                    warnings.warn(
                        "Template import %s/%s hides existing "
                        "attribute of class %s" % (template, name, cls_name))
                dict_[name] = cls._template_import(template_name, name)

            return type.__new__(cls, cls_name, bases, dict_)

        @classmethod
        def _template_import(cls, template_name, attribute):
            """Import template attribute from specified Jinja template file."""
            with app.app_context():
                return get_template_attribute(template_name, attribute)