1 files changed, 51 insertions, 2 deletions
diff --git a/spec/ruby/core/array/intersect_spec.rb b/spec/ruby/core/array/intersect_spec.rb
index b8c5b1e69a..62ac157278 100644
--- a/spec/ruby/core/array/intersect_spec.rb
+++ b/spec/ruby/core/array/intersect_spec.rb
@@ -1,17 +1,66 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe 'Array#intersect?' do
   ruby_version_is '3.1' do # https://bugs.ruby-lang.org/issues/15198
     describe 'when at least one element in two Arrays is the same' do
       it 'returns true' do
-        [1, 2].intersect?([2, 3]).should == true
+        [1, 2].intersect?([2, 3, 4]).should == true
+        [2, 3, 4].intersect?([1, 2]).should == true
       end
     end
 
     describe 'when there are no elements in common between two Arrays' do
       it 'returns false' do
-        [1, 2].intersect?([3, 4]).should == false
+        [0, 1, 2].intersect?([3, 4]).should == false
+        [3, 4].intersect?([0, 1, 2]).should == false
+        [3, 4].intersect?([]).should == false
+        [].intersect?([0, 1, 2]).should == false
       end
     end
+
+    it "tries to convert the passed argument to an Array using #to_ary" do
+      obj = mock('[1,2,3]')
+      obj.should_receive(:to_ary).and_return([1, 2, 3])
+
+      [1, 2].intersect?(obj).should == true
+    end
+
+    it "determines equivalence between elements in the sense of eql?" do
+      obj1 = mock('1')
+      obj2 = mock('2')
+      obj1.stub!(:hash).and_return(0)
+      obj2.stub!(:hash).and_return(0)
+      obj1.stub!(:eql?).and_return(true)
+      obj2.stub!(:eql?).and_return(true)
+
+      [obj1].intersect?([obj2]).should == true
+
+      obj1 = mock('3')
+      obj2 = mock('4')
+      obj1.stub!(:hash).and_return(0)
+      obj2.stub!(:hash).and_return(0)
+      obj1.stub!(:eql?).and_return(false)
+      obj2.stub!(:eql?).and_return(false)
+
+      [obj1].intersect?([obj2]).should == false
+    end
+
+    it "does not call to_ary on array subclasses" do
+      [5, 6].intersect?(ArraySpecs::ToAryArray[1, 2, 5, 6]).should == true
+    end
+
+    it "properly handles 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].intersect?([x]).should == true
+    end
+
+    it "has semantic of !(a & b).empty?" do
+      [].intersect?([]).should == false
+      [nil].intersect?([nil]).should == true
+    end
   end
 end