const test_cases = [ ("Empty", UInt8[], "text/plain; charset=utf-8"), ("Binary", UInt8[1, 2, 3], "application/octet-stream"), ("HTML document #1", HTTP.bytes("blah blah blah"), "text/html; charset=utf-8"), ("HTML document #2", HTTP.bytes(""), "text/html; charset=utf-8"), ("HTML document #3 (leading whitespace)", HTTP.bytes(" ..."), "text/html; charset=utf-8"), ("HTML document #4 (leading CRLF)", HTTP.bytes("\r\n..."), "text/html; charset=utf-8"), ("Plain text", HTTP.bytes("This is not HTML. It has ☃ though."), "text/plain; charset=utf-8"), ("XML", HTTP.bytes("\n