Use Rdebug When Debugging Statements Don't Take Effect

I was meta-meta-programming, and had an issue when an #included method was called:

1 anon = Module.new
2 anon.class_eval do
3 def self.included(base)
4 debugger
5 if some_method then
6 # code
7 else
8 # more code
9 end
10 end
11 end

The code above resulted in:

1 /Users/francois/Projects/project/lib/extensions.rb:214:in `included': undefined local variable or method `some_method' for #<Module:0x103305b20> (NameError)
2 from /Users/francois/Projects/project/lib/extensions.rb:245:in `include'
3 from /Users/francois/Projects/project/lib/extensions.rb:245:in `send'
4 ...
5

The debugger statement above just wouldn’t take: Ruby ran right over it. I happened to look at ruby-debug’s Rubygem spec file:

1 --- !ruby/object:Gem::Specification
2 name: ruby-debug
3 ...
4 executables:
5 - rdebug
6 ...

Oh, had never noticed the executables before… Sure enough, I managed to run under debugger control immediately:

1 $ rdebug -I test test/functional/ad_spots_controller_test.rb [-4, 5] in /Users/francois/Projects/bloom/adgear-admin/test/functional/ad_spots_controller_test.rb
2 => 1 require "test_helper"
3 2
4 3 class AdSpotsControllerTest < ActionController::TestCase
5 4
6 5 def setup
7 /Users/francois/Projects/bloom/adgear-admin/test/functional/ad_spots_controller_test.rb:1
8 require "test_helper"
9 (rdb:1)

From there, I was able to use (C)ontinue to end up on my debugger statement. Happy times ensued!

For the curious, the NoMethodError is because #some_method is defined on base, not on self. self in this context is the included module, while base is the place where we’re including it into.