Functional Testing of Web Applications

Framework Hooks

Frameworks can detect that they are in a testing environment by the presence (and truth) of the WSGI environmental variable "paste.testing" (the key name is inherited from paste.fixture).

More generally, frameworks can detect that something (possibly a test fixture) is ready to catch unexpected errors by the presence and truth of "paste.throw_errors" (this is sometimes set outside of testing fixtures too, when an error-handling middleware is in place).

Frameworks that want to expose the inner structure of the request may use "paste.testing_variables". This will be a dictionary – any values put into that dictionary will become attributes of the response object. So if you do env["paste.testing_variables"]['template'] = template_name in your framework, then response.template will be template_name.