canvas-lms/gems

Gems

This folder is a place to extract modular functionality from canvas. Canvas's Gemfile arrangement is enabled to read gems from this path locally without installing from a remote source. This is valuable for a few reasons:

• it prevents circular dependencies (bundler won't allow it)
• modularized code cannot bind to specific domain concepts on canvas models
• gems can have their specs run independently, without needing to load all of canvas, saving iteration time
• it allows for eventual build optimization via only running specs for the transitive closure of parents depending on a gem where a change is.

There are some tradeoffs:

• spreads canvas over more subdirectories, giving some mental overhad to traversing the entire codebase.
• modular tests necessarily don't test integration with canvas concepts, so solid integration tests in the app are still a requirement.
• total SERIALIZED build time goes up because each gem loads it's specs in a new process rather than all running within an already booted canvas process.

[TODO] eventually write more on whether we feel like those tradeoffs are good ones, and what the best practices are to leverage this pattern for max-gain/min-pain.

Testing

To test all the gems:

cd gems
./test_all_gems.sh

To test an individual gem

Run ./test.sh inside the gem's folder. This is basically the same as:

cd gems/google_drive
bundle
rspec