1 files changed, 33 insertions, 0 deletions
diff --git a/spec/rubyspec/library/set/sortedset/proper_subset_spec.rb b/spec/rubyspec/library/set/sortedset/proper_subset_spec.rb
new file mode 100644
index 0000000000..7e94774c1f
--- /dev/null
+++ b/spec/rubyspec/library/set/sortedset/proper_subset_spec.rb
@@ -0,0 +1,33 @@
+require File.expand_path('../../../../spec_helper', __FILE__)
+require 'set'
+
+describe "SortedSet#proper_subset?" do
+  before :each do
+    @set = SortedSet[1, 2, 3, 4]
+  end
+
+  it "returns true if passed a SortedSet that self is a proper subset of" do
+    SortedSet[].proper_subset?(@set).should be_true
+    SortedSet[].proper_subset?(SortedSet[1, 2, 3]).should be_true
+    SortedSet[].proper_subset?(SortedSet["a", "b", "c"]).should be_true
+
+    SortedSet[1, 2, 3].proper_subset?(@set).should be_true
+    SortedSet[1, 3].proper_subset?(@set).should be_true
+    SortedSet[1, 2].proper_subset?(@set).should be_true
+    SortedSet[1].proper_subset?(@set).should be_true
+
+    SortedSet[5].proper_subset?(@set).should be_false
+    SortedSet[1, 5].proper_subset?(@set).should be_false
+    SortedSet["test"].proper_subset?(@set).should be_false
+
+    @set.proper_subset?(@set).should be_false
+    SortedSet[].proper_subset?(SortedSet[]).should be_false
+  end
+
+  it "raises an ArgumentError when passed a non-SortedSet" do
+    lambda { SortedSet[].proper_subset?([]) }.should raise_error(ArgumentError)
+    lambda { SortedSet[].proper_subset?(1) }.should raise_error(ArgumentError)
+    lambda { SortedSet[].proper_subset?("test") }.should raise_error(ArgumentError)
+    lambda { SortedSet[].proper_subset?(Object.new) }.should raise_error(ArgumentError)
+  end
+end