diff --git a/core/range/to_set_spec.rb b/core/range/to_set_spec.rb
new file mode 100644
index 000000000..62c212164
--- /dev/null
+++ b/core/range/to_set_spec.rb
@@ -0,0 +1,43 @@
+require_relative '../../spec_helper'
+require_relative '../enumerable/fixtures/classes'
+
+describe "Enumerable#to_set" do
+  it "returns a new Set created from self" do
+    (1..4).to_set.should == Set[1, 2, 3, 4]
+    (1...4).to_set.should == Set[1, 2, 3]
+  end
+
+  it "passes down passed blocks" do
+    (1..3).to_set { |x| x * x }.should == Set[1, 4, 9]
+  end
+
+  ruby_version_is "4.0" do
+    it "instantiates an object of provided as the first argument set class" do
+      set = nil
+      proc{set = (1..3).to_set(EnumerableSpecs::SetSubclass)}.should complain(/Enumerable#to_set/)
+      set.should be_kind_of(EnumerableSpecs::SetSubclass)
+      set.to_a.sort.should == [1, 2, 3]
+    end
+
+    it "raises a RangeError if the range is infinite" do
+      -> { (1..).to_set }.should raise_error(RangeError, "cannot convert endless range to a set")
+      -> { (1...).to_set }.should raise_error(RangeError, "cannot convert endless range to a set")
+    end
+  end
+
+  ruby_version_is ""..."4.0" do
+    it "instantiates an object of provided as the first argument set class" do
+      set = (1..3).to_set(EnumerableSpecs::SetSubclass)
+      set.should be_kind_of(EnumerableSpecs::SetSubclass)
+      set.to_a.sort.should == [1, 2, 3]
+    end
+  end
+
+  it "does not need explicit `require 'set'`" do
+    output = ruby_exe(<<~RUBY, options: '--disable-gems', args: '2>&1')
+      puts (1..3).to_set.to_a.inspect
+    RUBY
+
+    output.chomp.should == "[1, 2, 3]"
+  end
+end