Currently our test suite only has to worry about HTTP/1.1, but with HTTP/2 support coming we're going to need to run tests both in HTTP/1.1 and HTTP/2 modes to avoid duplicating the entire test suite for the high-level tests like for PoolManager.

My proposal for the mechanism would be to control Hypercorn's ALPN to only offer http/1.1 or h2 depending on the test suite and then either run tests twice using a fixture or allowing external control somehow (environment variable?) and then running a separate job on CI? Open to other ideas too!