Update Rubocop and address the addressable todos

This is a big step forward in our Rubocop setup. I addressed all of the todos
from the current version of Rubocop that made sense to. The only things that
remain are metrics and one cop that relies on the line length metric to work.

I made some judgment calls on disabling a few cops:

1. The `Layout/IndentHeredoc` cop wants you to either use the squiggly heredoc
   from Ruby 2.3 or introduce a library. Since we are a low-level library that
   is used as a transitive dependency, we cannot introduce another library as a
   dependence, so that option is out. Also, we support Rubies back to 2.0
   currently, so using the squiggly heredoc isn't an option. Once we remove
   support for Rubies older than 2.3, we can switch to the squiggly heredoc cop.
2. The `Naming/FileName` cop was reporting false positives for a few files in
   the repository, so I disabled it on those files.
3. The `Style/DoubleNegation` cop reports lints on a few cases where we use
   double negation. Given the very generic nature of Hashie, the double-negation
   is the easiest, clearest way to express that we want an item to be a Boolean.
   I disabled the cop because we exist in the gray area where this makes sense.

1 files changed, 13 insertions, 14 deletions

diff --git a/lib/hashie/dash.rb b/lib/hashie/dash.rb
index a111e4b..ee27b11 100644
--- a/lib/hashie/dash.rb
+++ b/lib/hashie/dash.rb
@@ -15,7 +15,7 @@ module Hashie
   class Dash < Hash
     include Hashie::Extensions::PrettyInspect
 
-    alias_method :to_s, :inspect
+    alias to_s inspect
 
     # Defines a property on the Dash. Options are
     # as follows:
@@ -48,16 +48,14 @@ module Hashie
         define_method(property_assignment) { |value| self.[]=(property_name, value) }
       end
 
-      if defined? @subclasses
-        @subclasses.each { |klass| klass.property(property_name, options) }
-      end
+      @subclasses.each { |klass| klass.property(property_name, options) } if defined? @subclasses
 
       condition = options.delete(:required)
       if condition
         message = options.delete(:message) || "is required for #{name}."
         required_properties[property_name] = { condition: condition, message: message }
-      else
-        fail ArgumentError, 'The :message option should be used with :required option.' if options.key?(:message)
+      elsif options.key?(:message)
+        raise ArgumentError, 'The :message option should be used with :required option.'
       end
     end
 
@@ -111,8 +109,8 @@ module Hashie
       assert_required_attributes_set!
     end
 
-    alias_method :_regular_reader, :[]
-    alias_method :_regular_writer, :[]=
+    alias _regular_reader []
+    alias _regular_writer []=
     private :_regular_reader, :_regular_writer
 
     # Retrieve a value from the Dash (will return the
@@ -163,11 +161,12 @@ module Hashie
       update_attributes(attributes)
 
       self.class.defaults.each_pair do |prop, value|
+        next unless self[prop].nil?
         self[prop] = begin
           value.dup
         rescue TypeError
           value
-        end if self[prop].nil?
+        end
       end
       assert_required_attributes_set!
     end
@@ -208,11 +207,11 @@ module Hashie
     end
 
     def fail_property_required_error!(property)
-      fail ArgumentError, "The property '#{property}' #{self.class.required_properties[property][:message]}"
+      raise ArgumentError, "The property '#{property}' #{self.class.required_properties[property][:message]}"
     end
 
     def fail_no_property_error!(property)
-      fail NoMethodError, "The property '#{property}' is not defined for #{self.class.name}."
+      raise NoMethodError, "The property '#{property}' is not defined for #{self.class.name}."
     end
 
     def required?(property)
@@ -220,9 +219,9 @@ module Hashie
 
       condition = self.class.required_properties[property][:condition]
       case condition
-      when Proc   then !!(instance_exec(&condition))
-      when Symbol then !!(send(condition))
-      else             !!(condition)
+      when Proc   then !!instance_exec(&condition)
+      when Symbol then !!send(condition)
+      else             !!condition
       end
     end
   end