Add rails specific environment boostrapping

lib/mutant/bootstrap.rb

@@ -31,6 +31,7 @@ module Bootstrap
     #
     # rubocop:disable Metrics/MethodLength
     def self.apply(world, config)
+      # TOOD: Have this behind a conditional.
       config = Rails.call(world, config)
 
       env = Env

lib/mutant/bootstrap/rails.rb

@@ -1,29 +1,49 @@
 module Mutant
   module Bootstrap
-    module Rails
-      def self.call(world, config)
+    class Rails
+      include Procto.call, Concord.new(:world, :config)
+
+      def call
         world.stdout.puts('Loading mutant config from rails environment')
 
-        # TODO move to world.
+        # TODO add env to world.
+        #
+        # Make actual env configurable
         ENV['RAILS_ENV'] = 'test'
 
         world.kernel.require('./config/environment.rb')
 
         ::Rails.application.eager_load!
 
+        # TODO: preload engines, these *love* to pack things
+        # in the main project
+        #
+        # TODO: allow custom preload hooks.
+
+        add_rails_matchers
+      end
+
+    private
+
+      def add_rails_matchers
+        # This logic sucks, instead rails should be come a match expression
+        # possibly allow match expressions like: `ActionController.subclasses`
+        return config if config.matcher.match_expressions.any?
+
+        config.with(
+          matcher: config.matcher.with(match_expressions: rails_expressions)
+        )
+      end
+
+      def rails_expressions
         expressions = [
           ApplicationController,
           *ApplicationController.subclasses,
           ApplicationRecord,
           *ApplicationRecord.subclasses
         ].map { |klass| config.expression_parser.apply(klass.name).from_right }
-
-        config.with(
-          matcher: config.matcher.with(
-            match_expressions: config.matcher.match_expressions | expressions
-          )
-        )
       end
+
     end # Rails
   end # Bootstrap
 end # Mutant

lib/mutant/matcher/config.rb

@@ -51,9 +51,10 @@ def add(attribute, value)
       # @return [Config]
       def merge(other)
         self.class.new(
-          to_h
-            .map { |name, value| [name, value + other.public_send(name)] }
-            .to_h
+          ignore_expressions: other.ignore_expressions + ignore_expressions,
+          match_expressions:  other.match_expressions,
+          start_expressions:  other.start_expressions,
+          subject_filters:    other.subject_filters + subject_filters
         )
       end