1 files changed, 78 insertions, 0 deletions
diff --git a/spec/ruby/core/array/shared/difference.rb b/spec/ruby/core/array/shared/difference.rb
new file mode 100644
index 0000000000..3e69050d82
--- /dev/null
+++ b/spec/ruby/core/array/shared/difference.rb
@@ -0,0 +1,78 @@
+describe :array_binary_difference, shared: true do
+  it "creates an array minus any items from other array" do
+    [].send(@method, [ 1, 2, 4 ]).should == []
+    [1, 2, 4].send(@method, []).should == [1, 2, 4]
+    [ 1, 2, 3, 4, 5 ].send(@method, [ 1, 2, 4 ]).should == [3, 5]
+  end
+
+  it "removes multiple items on the lhs equal to one on the rhs" do
+    [1, 1, 2, 2, 3, 3, 4, 5].send(@method, [1, 2, 4]).should == [3, 3, 5]
+  end
+
+  it "properly handles recursive arrays" do
+    empty = ArraySpecs.empty_recursive_array
+    empty.send(@method, empty).should == []
+
+    [].send(@method, ArraySpecs.recursive_array).should == []
+
+    array = ArraySpecs.recursive_array
+    array.send(@method, array).should == []
+  end
+
+  it "tries to convert the passed arguments to Arrays using #to_ary" do
+    obj = mock('[2,3,3,4]')
+    obj.should_receive(:to_ary).and_return([2, 3, 3, 4])
+    [1, 1, 2, 2, 3, 4].send(@method, obj).should == [1, 1]
+  end
+
+  it "raises a TypeError if the argument cannot be coerced to an Array by calling #to_ary" do
+    obj = mock('not an array')
+    -> { [1, 2, 3].send(@method, obj) }.should raise_error(TypeError)
+  end
+
+  it "does not return subclass instance for Array subclasses" do
+    ArraySpecs::MyArray[1, 2, 3].send(@method, []).should be_an_instance_of(Array)
+    ArraySpecs::MyArray[1, 2, 3].send(@method, ArraySpecs::MyArray[]).should be_an_instance_of(Array)
+    [1, 2, 3].send(@method, ArraySpecs::MyArray[]).should be_an_instance_of(Array)
+  end
+
+  it "does not call to_ary on array subclasses" do
+    [5, 6, 7].send(@method, ArraySpecs::ToAryArray[7]).should == [5, 6]
+  end
+
+  it "removes an item identified as equivalent via #hash and #eql?" do
+    obj1 = mock('1')
+    obj2 = mock('2')
+    obj1.stub!(:hash).and_return(0)
+    obj2.stub!(:hash).and_return(0)
+    obj1.should_receive(:eql?).at_least(1).and_return(true)
+
+    [obj1].send(@method, [obj2]).should == []
+    [obj1, obj1, obj2, obj2].send(@method, [obj2]).should == []
+  end
+
+  it "doesn't remove an item with the same hash but not #eql?" do
+    obj1 = mock('1')
+    obj2 = mock('2')
+    obj1.stub!(:hash).and_return(0)
+    obj2.stub!(:hash).and_return(0)
+    obj1.should_receive(:eql?).at_least(1).and_return(false)
+
+    [obj1].send(@method, [obj2]).should == [obj1]
+    [obj1, obj1, obj2, obj2].send(@method, [obj2]).should == [obj1, obj1]
+  end
+
+  it "removes an identical item even when its #eql? isn't reflexive" do
+    x = mock('x')
+    x.stub!(:hash).and_return(42)
+    x.stub!(:eql?).and_return(false) # Stubbed for clarity and latitude in implementation; not actually sent by MRI.
+
+    [x].send(@method, [x]).should == []
+  end
+
+  it "is not destructive" do
+    a = [1, 2, 3]
+    a.send(@method, [1])
+    a.should == [1, 2, 3]
+  end
+end