path: root/wiki/src/blueprint/test_suite_getting_rid_of_the_jruby_mess.mdwn
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authorTails developers <>2014-12-03 13:01:52 +0100
committerTails developers <>2014-12-03 13:01:52 +0100
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+We want to drop the dependency of JRuby from our automated test suite,
+and move to native Ruby.
+**Ticket**: [[!tails_ticket 5731]]
+[[!toc levels=2]]
+# Why
+We depend on JRuby only because of the `sikuli-ruby` gem. Since
+Debian's JRuby is too old this forces us to use RVM to install a more
+recent JRuby *and* all required Ruby gems from RVM's non-Debian
+sources, even though most of them are packaged for Debian. For all we
+know, all of this can break in the future, especially after the Wheezy
+release. Also, some parts of the RVM/gem mess have none or at best
+scetchy authentication. Clearly we want all dependencies for the
+automated test suite to be in Debian, and this mess is a big blocker
+for that.
+Also, in JRuby 1.7 the C extension was deprecated, which means that
+two gems we depend on hsa become unusabe: `ruby-libvirt`, which is
+highly critical for us, and `system_timer`, which is not so critical.
+A move to native Ruby would put us in a much better position, since
+all gems are packaged in Debian, and native Ruby
+still has a C extension. To be able to do this we need a replacement
+for the `sikuli-ruby` gem, though.
+# Ways to replace the sikuli-ruby gem
+## Rjb
+[[rjb|<>]] seems maintained, if not actively developed.
+It is now in Debian Jessie and wheezy-backports.
+Other projects using it or interesting stuff at:
+* [rjb-require](
+* [rjb-examples](
+* [poi_pond]( (uses Rjb)
+* [Antrap]( (uses rjb)
+The jruby sikuli gem is quite simple, implementing it in Rjb can be as
+lightweight, or not.
+See [[!tails_ticket 6399]], `test/rjb-migration` branch.
+## Wrapping Sikuli commands via a stand-alone Sikuli server
+If the Rjb solution doesn't work out, this fallback is a drop-in
+replacement for the Sikuli gem, and that we know will work no matter
+what, and that should be reasonably easy to implement.
+In short, we create a pure Java program that controls a single
+`Screen` object, and listens for commands that that it translates into
+Sikuli API calls for that `Screen` object, and then responds
+appropriately to the calling client.
+### Details
+1. We write a pure Java program using the Java API for Sikuli, that
+ takes the `$DISPLAY`, image dir etc. as arguments and then sets up
+ all required Sikuli objects: Mouse and Keyboard robots, and a single
+ `Screen` object. Let's call this the "Sikuli server".
+1. The Sikuli server listens (on a UNIX socket, or whatever) for
+ "Sikuli commands" that it translates to Sikuli calls on the single
+ `Screen` object via the Sikuli API, and then translates the result
+ and sends that as a response.
+1. We completely re-write `sikuli_helper.rb`, defining a `Screen`
+ class (and possibly `Region`; see below). On `initialize()` it
+ starts a Sikuli server instance (simply via `Popen()` or whatever).
+ We implement simple wrappers for all methods we've used earlier
+ (i.e. `find()`, `wait()`, `type()`, `hover()` and `click()`) that
+ will send an appropriate command to the Sikuli server.
+### Example
+Say `screen` is an instance of `sikuli_helper.rb`'s `Screen`. Then
+`screen.wait("image.png", 100)` will result in something like
+`wait,image.png,100` being sent to the Sikuli server, which it
+translates into the call `screenObject.wait("image.png", 100)`, and
+responds back with something easily parsable, like
+`exception=ImageNotFound:Could not find image.png` (or whatever the
+exact exception name and message are) on failure, otherwise it just
+sends an ACK so `screen.wait()` can stop blocking execution.
+> I'd rather not invent a new protocol entirely, and instead
+> piggy-back e.g. on HTTP or something more appropriate. Also, I'd
+> rather use a well-known, well-defined serialization format (YAML,
+> JSON, you name it) instead of inventing a new one.
+### Obstacles
+* There may be some complexity to deal with `Region` objects (returned
+ by e.g. `find()`, which we use in `wait_and_click()`) since we'd
+ need some way (an identifier?) to know which `Region` object in
+ `sikuli_helper.rb` corresponds to which `Region` (Java) object in
+ the Sikuli server; we avoid this issue with `Screen` since each
+ Sikuli server deals with a single `Screen` object, but we can
+ potentially deal with any number of `Region` objects. A simple
+ solution would be to only store the appropriate coordinates and
+ dimensions in `sikuli_helper.rb`'s `Region` object and then whenever
+ it's used we create a new `Region` object in the Sikuli server using
+ those coordinates and dimensions. We could then implement methods
+ via the `Screen` object, like `` could use those
+ coordinates and dimensions to `` on the right place.
+ We currently only use `Region` in our `wait_and_click` helper, so
+ a ad-hoc solution would probably be enough.
+* Getting Sikuli's key constants (e.g. `Sikuli::KEY_CTRL`) into
+ `sikuli_helper.rb` is not completely trivial. Perhaps we could make
+ the Sikuli server send the values of all these so they can be stored
+ into the appropriate constants upon `Screen.initialize()`, when the
+ server is first contacted? Otherwise we can always statically define
+ them with magic values.
+# Roadmap
+Complete the move to Rjb in `test/rjb-migration`.