Bugfix: make possible to use RSpec::Matchers#include inside a custom …

…matcher

That bug was happening because RSpec::Matchers::DSL::Matcher has a
`include` private method that was overriding the `include` method
include from RSpec::Matchers.

lib/rspec/matchers/matcher.rb

@@ -238,7 +238,15 @@ def method_missing(method, *args, &block)
         end
 
         def include(*args)
-          singleton_class.__send__(:include, *args)
+          if trying_to_include_a_module?(*args)
+            singleton_class.__send__(:include, *args)
+          else
+            BuiltIn::Include.new(*args)
+          end
+        end
+
+        def trying_to_include_a_module?(*args)
+          args.first.is_a?(Module)
         end
 
         def define_method(name, &block)

spec/rspec/matchers/matcher_spec.rb

@@ -327,6 +327,17 @@ def second_word
       expect(matcher.matches?(8)).to be_true
     end
 
+    it "has access to the built in include matcher" do
+      matcher = RSpec::Matchers::DSL::Matcher.new(:ignore) do |expected|
+        match do |actual|
+          extend RSpec::Matchers
+          expect(actual).to include(expected)
+        end
+      end.for_expected(3)
+
+      expect(matcher.matches?([1, 2, 3])).to be_true
+    end
+
     context 'when multiple instances of the same matcher are used in the same example' do
       RSpec::Matchers.define(:be_like_a) do |expected|
         match { |actual| actual == expected }