While it is easy to create test cases for conditions that don’t satisfy this requirement, it is somewhat more difficult to determine how third-party libraries will handle HTTP requests that fall outside this constraint. I looked around the internet for websites to help me test weird status codes, but most of them only let me test with the known status codes. As such, I decided to add arbitrary HTTP status codes to my naughty httpbin fork, called misbehaving.site.
What I discovered is that the various browser manufacturers have wildly different behavior with how they handle unknown HTTP status codes.
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