1 files changed, 34 insertions, 0 deletions
diff --git a/spec/ruby/library/set/subset_spec.rb b/spec/ruby/library/set/subset_spec.rb
new file mode 100644
index 0000000000..6503a7539f
--- /dev/null
+++ b/spec/ruby/library/set/subset_spec.rb
@@ -0,0 +1,34 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+require 'set'
+
+describe "Set#subset?" do
+  before :each do
+    @set = Set[1, 2, 3, 4]
+  end
+
+  it "returns true if passed a Set that is equal to self or self is a subset of" do
+    @set.subset?(@set).should be_true
+    Set[].subset?(Set[]).should be_true
+
+    Set[].subset?(@set).should be_true
+    Set[].subset?(Set[1, 2, 3]).should be_true
+    Set[].subset?(Set["a", :b, ?c]).should be_true
+
+    Set[1, 2, 3].subset?(@set).should be_true
+    Set[1, 3].subset?(@set).should be_true
+    Set[1, 2].subset?(@set).should be_true
+    Set[1].subset?(@set).should be_true
+
+    Set[5].subset?(@set).should be_false
+    Set[1, 5].subset?(@set).should be_false
+    Set[nil].subset?(@set).should be_false
+    Set["test"].subset?(@set).should be_false
+  end
+
+  it "raises an ArgumentError when passed a non-Set" do
+    lambda { Set[].subset?([]) }.should raise_error(ArgumentError)
+    lambda { Set[].subset?(1) }.should raise_error(ArgumentError)
+    lambda { Set[].subset?("test") }.should raise_error(ArgumentError)
+    lambda { Set[].subset?(Object.new) }.should raise_error(ArgumentError)
+  end
+end