1 files changed, 30 insertions, 0 deletions
diff --git a/spec/ruby/core/enumerable/sum_spec.rb b/spec/ruby/core/enumerable/sum_spec.rb
new file mode 100644
index 0000000000..4881039a8d
--- /dev/null
+++ b/spec/ruby/core/enumerable/sum_spec.rb
@@ -0,0 +1,30 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+require File.expand_path('../fixtures/classes', __FILE__)
+
+ruby_version_is '2.4' do
+  describe 'Enumerable#sum' do
+    before :each do
+      @enum = Object.new.to_enum
+      class << @enum
+        def each
+          yield 0
+          yield(-1)
+          yield 2
+          yield 2/3r
+        end
+      end
+    end
+
+    it 'returns amount of the elements with taking an argument as the initial value' do
+      @enum.sum(10).should == 35/3r
+    end
+
+    it 'gives 0 as a default argument' do
+      @enum.sum.should == 5/3r
+    end
+
+    it 'takes a block to transform the elements' do
+      @enum.sum { |element| element * 2 }.should == 10/3r
+    end
+  end
+end