check for method existance in a ruby 1.8- and 1.9-compatible way

this is a cherry-pick of ed6785b
[mislav#269 state:resolved]

lib/will_paginate.rb

@@ -17,7 +17,7 @@ def enable
 
     # hooks WillPaginate::ViewHelpers into ActionView::Base
     def enable_actionpack
-      return if ActionView::Base.instance_methods.include? 'will_paginate'
+      return if ActionView::Base.instance_methods.include_method? :will_paginate
       require 'will_paginate/view_helpers'
       ActionView::Base.send :include, ViewHelpers
 

lib/will_paginate/core_ext.rb

@@ -1,7 +1,18 @@
 require 'set'
 require 'will_paginate/array'
 
-unless Hash.instance_methods.include? 'except'
+# helper to check for method existance in ruby 1.8- and 1.9-compatible way
+# because `methods`, `instance_methods` and others return strings in 1.8 and symbols in 1.9
+#
+#   ['foo', 'bar'].include_method?(:foo) # => true
+class Array
+  def include_method?(name)
+    name = name.to_sym
+    !!(find { |item| item.to_sym == name })
+  end
+end
+
+unless Hash.instance_methods.include_method? :except
   Hash.class_eval do
     # Returns a new hash without the given keys.
     def except(*keys)
@@ -16,7 +27,7 @@ def except!(*keys)
   end
 end
 
-unless Hash.instance_methods.include? 'slice'
+unless Hash.instance_methods.include_method? :slice
   Hash.class_eval do
     # Returns a new hash with only the given keys.
     def slice(*keys)

lib/will_paginate/finder.rb

@@ -214,7 +214,7 @@ def wp_count(options, args, finder)
 
         # forget about includes if they are irrelevant (Rails 2.1)
         if count_options[:include] and
-            klass.private_methods.include?('references_eager_loaded_tables?') and
+            klass.private_methods.include_method?(:references_eager_loaded_tables?) and
             !klass.send(:references_eager_loaded_tables?, count_options)
           count_options.delete :include
         end

test/finder_test.rb

@@ -284,11 +284,11 @@ def test_readonly
   # this functionality is temporarily removed
   def xtest_pagination_defines_method
     pager = "paginate_by_created_at"
-    assert !User.methods.include?(pager), "User methods should not include `#{pager}` method"
+    assert !User.methods.include_method?(pager), "User methods should not include `#{pager}` method"
     # paginate!
     assert 0, User.send(pager, nil, :page => 1).total_entries
     # the paging finder should now be defined
-    assert User.methods.include?(pager), "`#{pager}` method should be defined on User"
+    assert User.methods.include_method?(pager), "`#{pager}` method should be defined on User"
   end
 
   # Is this Rails 2.0? Find out by testing find_all which was removed in [6998]
@@ -440,7 +440,7 @@ def test_paginated_each_with_named_scope
     end
 
     # detect ActiveRecord 2.1
-    if ActiveRecord::Base.private_methods.include?('references_eager_loaded_tables?')
+    if ActiveRecord::Base.private_methods.include_method?(:references_eager_loaded_tables?)
       def test_removes_irrelevant_includes_in_count
         Developer.expects(:find).returns([1])
         Developer.expects(:count).with({}).returns(0)