Package urlfetch provides a way for an application to get http.RoundTripper that can make outbound HTTP requests. If used for https:// protocol, will always validate SSL certificates.
Get pulls http.RoundTripper implementation from context or panics if it wasn't set. Use SetFactory(...) or Set(...) in unit tests to mock the round tripper.
Set sets the current http.RoundTripper object in the context. Useful for testing with a quick mock. This is just a shorthand SetFactory invocation to set a factory which always returns the same object.