'Assert that `email_user` was used to send and email with the supplied subject and body
`email_user`: The mock `django.contrib.auth.models.User.email_user` function
to verify
`subject_template`: The template to have been used for the subject
`subject_context`: The context to have been used for the subject
`body_template`: The template to have been used for the body
`body_context`: The context to have been used for the body'

def assertEmailUser(self, email_user, subject_template, subject_context, body_template, body_context):

    email_user.assert_called_with(mock_render_to_string(subject_template, subject_context), mock_render_to_string(body_template, body_context), configuration_helpers.get_value('email_from_address', settings.DEFAULT_FROM_EMAIL))
