1 files changed, 53 insertions, 0 deletions
diff --git a/spec/ruby/core/enumerator/chain/rewind_spec.rb b/spec/ruby/core/enumerator/chain/rewind_spec.rb
new file mode 100644
index 0000000000..61b07b8c0a
--- /dev/null
+++ b/spec/ruby/core/enumerator/chain/rewind_spec.rb
@@ -0,0 +1,53 @@
+require_relative '../../../spec_helper'
+
+ruby_version_is "2.6" do
+  describe "Enumerator::Chain#rewind" do
+    before(:each) do
+      @obj = mock('obj')
+      @obj.should_receive(:each).any_number_of_times.and_yield(42)
+      @second = mock('obj')
+      @second.should_receive(:each).any_number_of_times.and_yield(:second)
+      @enum = Enumerator::Chain.new(@obj, @second)
+    end
+
+    it "returns self" do
+      @enum.rewind.should equal @enum
+    end
+
+    it "does nothing if receiver has not been iterated" do
+      @obj.should_not_receive(:rewind)
+      @obj.respond_to?(:rewind).should == true # sanity check
+      @enum.rewind
+    end
+
+    it "does nothing on objects that don't respond_to rewind" do
+      @obj.respond_to?(:rewind).should == false # sanity check
+      @enum.each {}
+      @enum.rewind
+    end
+
+    it "calls_rewind its objects" do
+      @obj.should_receive(:rewind)
+      @enum.each {}
+      @enum.rewind
+    end
+
+    it "calls_rewind in reverse order" do
+      @obj.should_not_receive(:rewind)
+      @second.should_receive(:rewind).and_raise(RuntimeError)
+      @enum.each {}
+      lambda { @enum.rewind }.should raise_error(RuntimeError)
+    end
+
+    it "calls rewind only for objects that have actually been iterated on" do
+      @obj = mock('obj')
+      @obj.should_receive(:each).any_number_of_times.and_raise(RuntimeError)
+      @enum = Enumerator::Chain.new(@obj, @second)
+
+      @obj.should_receive(:rewind)
+      @second.should_not_receive(:rewind)
+      lambda { @enum.each {} }.should raise_error(RuntimeError)
+      @enum.rewind
+    end
+  end
+end