Extract errors to its own module

lib/robinet/errors.rb

@@ -0,0 +1,12 @@
+module Robinet
+  module Errors
+    class RateLimitExceeded < StandardError
+      def http_response
+        [429, {}, ['Rate Limit Exceeded']]
+      end
+    end
+
+    class InvalidRateLimit < StandardError
+    end
+  end
+end

lib/robinet/parser.rb

@@ -4,12 +4,9 @@ class Parser
     SINGLE_EXPR = /\s*([0-9]+)\s*(\/|\s*per\s*)\s*([0-9]+)*\s*(hour|minute|second|day|month|year)s?\s*/i
     EXPR = /^#{SINGLE_EXPR}(:?#{SEPARATORS}#{SINGLE_EXPR})*$/i
 
-    class InvalidRateLimit < StandardError
-
-    end
 
     def self.extract(limit_string)
-      raise InvalidRateLimit unless EXPR.match(limit_string)
+      raise Errors::InvalidRateLimit unless EXPR.match(limit_string)
       limit_string.split(SEPARATORS).map do |limit|
         _, amount, _, multiples, granularity = *SINGLE_EXPR.match(limit)
         Robinet::Limit.new(amount, multiples, granularity)

spec/parser_spec.rb

@@ -1,7 +1,7 @@
 describe Robinet::Parser do
   describe '#test' do
     it 'raises an error for an empty limit' do
-      expect{Robinet::Parser.extract('')}.to raise_error Robinet::Parser::InvalidRateLimit
+      expect{Robinet::Parser.extract('')}.to raise_error Robinet::Errors::InvalidRateLimit
     end
     it 'returns an array of a single limit' do
       expect(Robinet::Parser.extract('5 per minute')).to eq([Robinet::Limit.new(5, 1, :minute)])