1 files changed, 31 insertions, 0 deletions
diff --git a/spec/ruby/library/set/fixtures/set_like.rb b/spec/ruby/library/set/fixtures/set_like.rb
new file mode 100644
index 0000000000..46f61a451e
--- /dev/null
+++ b/spec/ruby/library/set/fixtures/set_like.rb
@@ -0,0 +1,31 @@
+require 'set'
+
+module SetSpecs
+  # This class is used to test the interaction of "Set-like" objects with real Sets
+  #
+  # These "Set-like" objects reply to is_a?(Set) with true and thus real Set objects are able to transparently
+  # interoperate with them in a duck-typing manner.
+  class SetLike
+    include Enumerable
+
+    def is_a?(klass)
+      super || klass == ::Set
+    end
+
+    def initialize(entries)
+      @entries = entries
+    end
+
+    def each(&block)
+      @entries.each(&block)
+    end
+
+    def inspect
+      "#<#{self.class}: {#{map(&:inspect).join(", ")}}>"
+    end
+
+    def size
+      @entries.size
+    end
+  end
+end