fixes without_count last_page? behaviour (#1009)

* fixes without_count last_page? behaviour
* attempt to handle older versions for arel
* typo
* should be checking limit class after super too
* stricter class checking
* fixes rails 4.{1,2}
* made adjustable? more readable
* regression tests for without_count

kaminari-activerecord/lib/kaminari/activerecord/active_record_relation_methods.rb

@@ -59,11 +59,11 @@ def load
       else
         @values[:limit] = limit_value + 1
         # FIXME: this could be removed when we're dropping AR 4 support
-        @arel.limit = @values[:limit] if @arel && (Integer === @arel.limit)
+        @arel.limit = adjusted_limit(@values[:limit]) if @arel && adjustable?(@arel.limit)
         super
         @values[:limit] = limit_value - 1
         # FIXME: this could be removed when we're dropping AR 4 support
-        @arel.limit = @values[:limit] if @arel && (Integer === @arel.limit)
+        @arel.limit = adjusted_limit(@values[:limit]) if @arel && adjustable?(@arel.limit)
 
         if @records.any?
           @records = @records.dup if (frozen = @records.frozen?)
@@ -75,6 +75,19 @@ def load
       end
     end
 
+    def adjustable?(obj)
+      obj.class == Integer || obj.class == Fixnum || (obj.class == Arel::Nodes::BindParam && obj.respond_to?(:value))
+    end
+
+    def adjusted_limit(limit)
+      case @arel.limit.class
+      when Integer, Fixnum
+        limit
+      when Arel::Nodes::BindParam
+        Arel::Nodes::BindParam.new(@arel.limit.value.with_cast_value(limit))
+      end
+    end
+
     # The page wouldn't be the last page if there's "limit + 1" record
     def last_page?
       !out_of_range? && !@_has_next

kaminari-core/test/models/active_record/paginable_without_count_test.rb

@@ -70,6 +70,22 @@ def self.shutdown
       assert @users.out_of_range?
     end
 
+    test 'regression: call arel first' do
+      @user = User.page(1).without_count
+      @user.arel
+
+      assert_equal false, @user.last_page?
+    end
+
+    test 'regression: call last page first' do
+      @user = User.page(1).without_count
+
+      @user.last_page?
+      @user.arel
+
+      assert_equal false, @user.last_page?
+    end
+
     def assert_no_queries
       subscriber = ActiveSupport::Notifications.subscribe 'sql.active_record' do
         raise 'A SQL query is being made to the db:'