Support running tests in Rails engines

[tristil]

Motivation

In Rails projects with engines, you need to cd into the engine in order to run a test, or else requires, etc. will not work.

Implementation

This change detects when a file has engines in its path and has a Rails dependency and alters the command to cd in (and out, afterwards) of the engine. This allows running a test and sending the test to terminal. The special characters involved break debug, which is fixed in the second commit. The second commit escapes the command when passing to rdbg.

Automated Tests

Tests added

Manual Tests

I am able to run tests in an engine using VS Code

[st0012]

@tristil have you tried installing the ruby-lsp-rails addon? With it, the code lens feature would use bin/rails test to execute the tests instead of ruby -Itest, which may take the engine setup into consideration.

[tristil]

@st0012 I tried it out and it didn't work. When running engine tests manually we always cd into the engine directory.

[st0012]

Can you explain how it didn't work? Was the bin/rails test command didn't work, or the path was not correct, or was it something else?

[tristil]

@st0012 I run ./bin/rails test engines/some_engine/test/some_engine/some_file_test.rb and I get require: cannot load such file -- some_helper (LoadError) but if I cd into engines/some_engine I can run bundle exec ruby -Itest test/some_engine/some_file_test.rb without an error

[tristil]

Some context is that we are a big company with a Rails monolith that is divided into 40+ engines. So although it's true that we could open vscode, etc. in each engine it would be a lot of context switching especially since there are interactions between engines and the top level app.

[vinistock]

Sorry about the lack of feedback. The main issue with this is solving it in a general way that works for any app using engines.

My understanding is that you don't have to put the engines under the engines directory, so assuming that will likely not work for everybody.

Also, depending on your Gemfile setup, then the files in engines are available for require from the top level, avoiding this issue.

If you discover that there is a convention about how to run tests inside engines and where to put them or if you find an alternative that works generally, please let us know.

[tristil]

@vinistock Sorry, I should have left a comment about why I was closing. Basically I think this is too specific to my organization's needs, plus we are moving away from engines to Packwerk packs. But: the underlying problem is that ruby-lsp wants there to be a Gemfile at the root of a project, even if there is also a .gemspec file, and in general it doesn't understand how to load an engine in isolation (or at least I couldn't figure it out). If it did know how to do these things then we could have set up our app as a multi root project as recommended and we wouldn't need special handling. IOW if it were possible for ruby-lsp to work with a single engine (or a single inline gem without an explicit Gemfile) then multi root project would have served our needs.