| 1 | ---
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| 2 | default_highlighter: oils-sh
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| 3 | ---
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| 4 | 
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| 5 | BYO - Protocols for Test Discovery, Shell Completion
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| 6 | ===========
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| 7 | 
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| 8 | BYO is a simple mechanism to turn CLI processes into "servers" which respond to
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| 9 | requests encoded in environment variables.
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| 10 | 
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| 11 | Points of reference:
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| 12 | 
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| 13 | - [Test Anything Protocol][TAP]
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| 14 |   - e.g. Perl scripts parse stdout of test processes in any language
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| 15 | - [Shellac Protocol Proposal V2]($wiki) (wiki, 2019)
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| 16 | 
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| 17 | (About the name: It originally stood for Bash YSH OSH.  But "bring your own" is
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| 18 | a good acronym!)
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| 19 | 
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| 20 | [TAP]: https://testanything.org/
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| 21 | 
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| 22 | <div id="toc">
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| 23 | </div> 
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| 24 | 
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| 25 | ## The General Idea
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| 26 | 
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| 27 | Executables should respond to the `BYO_COMMAND` environment variable:
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| 28 | 
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| 29 |     BYO_COMMAND=foo
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| 30 | 
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| 31 | And `BYO_ARG=bar` varies based on the command.
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| 32 | 
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| 33 | A library that implements this is:
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| 34 | 
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| 35 |     source $LIB_OSH/byo-server.sh
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| 36 | 
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| 37 | But it's designed to be implemented in Python, C++, etc.
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| 38 | 
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| 39 | A client is:
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| 40 | 
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| 41 |     test/byo-client.sh detect myscript.sh
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| 42 | 
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| 43 | 
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| 44 | ## Protocol
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| 45 | 
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| 46 | ### Detecting BYO Servers
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| 47 | 
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| 48 | Here's how you detect if an executable supports BYO:
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| 49 | 
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| 50 |     $ BYO_COMMAND=detect ./any-executable </dev/null
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| 51 |     list-tests
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| 52 |     run-tests
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| 53 | 
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| 54 |     # must exit with code 66, which is ASCII 'B'
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| 55 | 
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| 56 | ### Testing - discover and run
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| 57 | 
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| 58 | List tests first:
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| 59 | 
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| 60 |     BYO_COMMAND=list-tests   
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| 61 | 
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| 62 | Then run them one at a time:
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| 63 | 
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| 64 |     BYO_COMMAND=run-test
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| 65 |     BYO_ARG=foo
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| 66 | 
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| 67 | ### Shell completion - use these primitives
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| 68 | 
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| 69 | TODO:
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| 70 | 
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| 71 |     BYO_COMMAND=list-tasks  # related to task-five
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| 72 |     BYO_COMMAND=list-flags  # only some binaries have flags
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| 73 | 
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| 74 | <!--
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| 75 | Note: Look at Clang and npm completion?
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| 76 | -->
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| 77 | 
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| 78 | ## Client Tool
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| 79 | 
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| 80 | The tool should work like this:
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| 81 | 
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| 82 |     $ byo detect myscript.sh
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| 83 |     $ byo test myscript.sh
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| 84 | 
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| 85 | (Right now it's [test/byo-client.sh]($oils-src))
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| 86 | 
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| 87 | ## Appendix: Future Work
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| 88 | 
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| 89 | ### Other Applications
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| 90 | 
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| 91 | - Benchmarking with TSV output
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| 92 | - Building tests first, with Ninja
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| 93 | - Deployment
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| 94 | 
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| 95 | Runtime:
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| 96 | 
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| 97 | - Gateway Interface / Coprocess
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| 98 |   - like FastCGI / CGI
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| 99 | - Logs
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| 100 | 
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| 101 | Points of reference:
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| 102 | 
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| 103 | - 12 factor app for Hosting (Heroku)
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| 104 | - CGI / FastCGI
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| 105 | 
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| 106 | ### Coprocesses
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| 107 | 
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| 108 | Instead of a fresh process env variables, we might want to detect coprocesses.
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| 109 | 
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