Catch HTTP adapter run_forever failures in test fixture

[rosesyrett]

Currently on master, running pytest if port 8080 on localhost is bound freezes the output. The terminal simply hangs. I have investigated the issue and fixed this by changing the fixture where this is happening so that it keeps track of the task that calls .run_forever on the adaptor as well as .wait_until_ready and waits until one of those completes.

wait_until_ready will only ever be set if run_forever gets far enough to set it; if, for example, the server cannot be instantiated, this fails silently, and wait_until_ready therefore waits forever.

[codecov]

Codecov Report

Merging #165 (539d44d) into master (9380b1a) will not change coverage.
The diff coverage is n/a.

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