Add Set Default Tasks For Rake To Run as a Ruby TIL

ruby/set-default-tasks-for-rake-to-run.md

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+# Set Default Tasks For Rake To Run
+
+Let's say our Ruby codebase has a `test` rake task and a `test:system` rake
+task. One runs our unit tests and the other runs our system (headless
+browser-based) tests. They aren't necessary defined in our `Rakefile`. In fact,
+that's how it is in a Rails codebase where these are defined by Rails itself.
+
+We want the default action when [`rake`](https://ruby.github.io/rake/) is
+invoked by itself to be to run both of those test tasks.
+
+This can be accomplished by specifying a `default` task and specifying both of
+those tasks as prerequisites.
+
+```ruby
+task default: ["test", "test:system"]
+```
+
+The `default` task itself does nothing. When we invoke it though, it has to run
+our prerequisites. So running `rake` results in `test` and then `test:system`
+getting run.
+
+If I have something like
+[`unicornleap`](https://github.com/dkarter/dotfiles/blob/b5aae6a9edd5766f0cc9100235b0955a9d53aa85/installer/mac-setup.sh#L47-L74)
+or
+[`confetti`](https://manual.raycast.com/deeplinks#block-702a9613bc82440d853492f553876a20),
+then I can have one of those run in the event that all the prerequisites pass.
+
+```ruby
+task default: ["test", "test:system"] do
+  system("unicornleap") if system("which unicornleap > /dev/null 2>&1")
+end
+```