Stenographer logging and playback

[maxlinc]

Details from the WIP README for upcoming v0.4.0

The Stenographer

The stenographer keeps a short-hand record of everything that happens in the courtroom. These logs can be used for troubleshooting, creating reports, or re-enacting the courtroom activities at a later date (and with different actors.

The stenographer's logs are similar to HTTP access logs in this respect, but in a format that's more compact and suited to Pacto. A typical HTTP access log might look like this:

#Fields: date time c-ip cs-username s-ip s-port cs-method cs-uri-stem cs-uri-query sc-status cs(User-Agent)
2014-07-01 17:42:15 127.0.0.1 - 127.0.0.1 80 PUT /store/album/123/cover_art - 201 curl/7.30.0
2014-07-01 17:42:18 127.0.0.1 - 127.0.0.1 80 GET /store/album/123/cover_art size=small 200 curl/7.30.0

If Pacto has the following services registered:

Then it can match those requests to request and generate a stenographer log that looks like this:

request 'Upload Album Art', values: {album_id: '123'}, response: {status: 201} # no contract violations
request 'Download Album Art', values: {album_id: '123', size: 'small'}, response: {status: 200} # no contract violations

This log file is designed so Pacto it can be used by Pacto to simulate the requests:

Pacto.simulate_consumer :my_client do
  request 'Upload Album Art', values: {album_id: '123'}, response: {status: 201} # no contract violations
  request 'Download Album Art', values: {album_id: '123', size: 'small'}, response: {status: 200} # no contract violations
end

Since Pacto has added a layer of abstraction you can experiment with changes to the contracts (including routing) without needing to re-record the interactions with the stenographer. For example Pacto will adjust if you change the route from:

to

[maxlinc]

See also samples/stenographer.rb for some stuff that's not currently in the README. In particular, you can playback a stenographer log file without copying pasting:

Pacto.simulate_consumer :my_consumer do
  playback 'pacto_stenographer.log'
end

In the future it may make sense to have something like rake validate which takes a stenographer log and replays each request (w/ variations for different values) rather than just one request per contract.
That'd let a consumer (e.g. in java) launch a pacto server and point their test suite at it (w/ pacto either stubbed or hitting the live service). They could then hand the contracts and stenographer log over the the provider, who could use just pacto to replay the requests w/out the dependency on the consumer (java).

[coveralls]

Changes Unknown when pulling fe8548b on stenographer into * on master*.