1 files changed, 29 insertions, 0 deletions
diff --git a/spec/ruby/core/set/merge_spec.rb b/spec/ruby/core/set/merge_spec.rb
new file mode 100644
index 0000000000..a2c1a7e706
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+++ b/spec/ruby/core/set/merge_spec.rb
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+require_relative '../../spec_helper'
+
+describe "Set#merge" do
+  it "adds the elements of the passed Enumerable to self" do
+    Set[:a, :b].merge(Set[:b, :c, :d]).should == Set[:a, :b, :c, :d]
+    Set[1, 2].merge([3, 4]).should == Set[1, 2, 3, 4]
+  end
+
+  it "returns self" do
+    set = Set[1, 2]
+    set.merge([3, 4]).should.equal?(set)
+  end
+
+  it "raises an ArgumentError when passed a non-Enumerable" do
+    -> { Set[1, 2].merge(1) }.should.raise(ArgumentError)
+    -> { Set[1, 2].merge(Object.new) }.should.raise(ArgumentError)
+  end
+
+  it "raises RuntimeError when called during iteration" do
+    set = Set[:a, :b]
+    set.each do |_m|
+      -> { set.merge([1, 2]) }.should.raise(RuntimeError, /iteration/)
+    end
+  end
+
+  it "accepts multiple arguments" do
+    Set[:a, :b].merge(Set[:b, :c], [:d]).should == Set[:a, :b, :c, :d]
+  end
+end