MONGOID-5258 Review enumerable === implementation (#5180)

Co-authored-by: Oleg Pudeyev <[email protected]>

Author: p-mongo

docs/release-notes/mongoid-7.4.txt

@@ -50,17 +50,25 @@ Mongoid 7.4, the ``===`` operator will function as it did in Mongoid 7.3:
 ``===`` returned ``true`` for some cases when the equivalent Ruby
 ``===`` implementation returned false, as per the examples below.
 
-Mongoid 7.4 behavior:
+Mongoid 7.4 with ``Mongoid.legacy_triple_equals`` set to ``false`` behavior:
 
 .. code-block:: ruby
 
   class Band
     include Mongoid::Document
+    
+    has_many :members
   end
 
   class CoverBand < Band
   end
 
+  class Member
+    include Mongoid::Document
+    
+    belongs_to :band
+  end
+
   band = Band.new
   cover_band = CoverBand.new
 
@@ -75,8 +83,15 @@ Mongoid 7.4 behavior:
 
   CoverBand === Band
   # => false
+  
+  band.members === Array
+  # => false
+  
+  band.members === Mongoid::Association::Referenced::HasMany::Enumerable
+  # => false
 
-Mongoid 7.3 behavior:
+Mongoid 7.3 and 7.4 with ``Mongoid.legacy_triple_equals`` set to ``true``
+behavior:
 
 .. code-block:: ruby
 
@@ -91,6 +106,12 @@ Mongoid 7.3 behavior:
 
   CoverBand === Band
   # => true
+  
+  band.members === Array
+  # => true
+  
+  band.members === Mongoid::Association::Referenced::HasMany::Enumerable
+  # => true
 
 The standard invocation of ``===``, that is having the class on the left and
 the instance on the right, works the same in Mongoid 7.4 as it did previously

lib/mongoid/association/referenced/has_many/enumerable.rb

@@ -34,8 +34,8 @@ def ==(other)
             entries == other.entries
           end
 
-          # Check equality of the enumerable against the provided object for case
-          # statements.
+          # Check equality of the enumerable against the provided object for
+          # case statements.
           #
           # @example Check case equality.
           #   enumerable === Array
@@ -44,7 +44,12 @@ def ==(other)
           #
           # @return [ true, false ] If the objects are equal in a case.
           def ===(other)
-            other.class == Class ? (Array == other || Enumerable == other) : self == other
+            return false unless other.respond_to?(:entries)
+            if Mongoid.legacy_triple_equals
+              other.class == Class ? (Array == other || Enumerable == other) : self == other
+            else
+              entries === other.entries
+            end
           end
 
           # Append a document to the enumerable.

spec/mongoid/association/referenced/has_many/enumerable_spec.rb

@@ -113,55 +113,86 @@
 
   describe "#===" do
 
-    let(:enumerable) do
-      described_class.new([])
-    end
+    let(:data) { [] }
 
-    context "when compared to an array class" do
+    shared_examples 'standard library-compatible enumerable' do
+      context "when compared to an array class" do
 
-      it "returns true" do
-        expect(enumerable === Array).to be true
+        it "returns false" do
+          expect(enumerable === Array).to be false
+        end
       end
-    end
 
-    context "when compared to an enumerable class" do
+      context "when compared to an enumerable class" do
 
-      it "returns true" do
-        expect(enumerable === described_class).to be true
+        it "returns false" do
+          expect(enumerable === described_class).to be false
+        end
       end
-    end
 
-    context "when compared to a different class" do
+      context "when compared to a different class" do
 
-      it "returns false" do
-        expect(enumerable === Mongoid::Document).to be false
+        it "returns false" do
+          expect(enumerable === Mongoid::Document).to be false
+        end
       end
-    end
 
-    context "when compared to an array instance" do
+      context "when compared to an array instance" do
 
-      context "when the entries are equal" do
+        context "when the entries are equal" do
 
-        let(:other) do
-          described_class.new([])
-        end
+          let(:data) do
+            [Post.new(id: 2)]
+          end
 
-        it "returns true" do
-          expect(enumerable === other).to be true
+          let(:other) do
+            described_class.new([Post.new(id: 2)])
+          end
+
+          it "returns true" do
+            expect(enumerable === other).to be true
+          end
         end
-      end
 
-      context "when the entries are not equal" do
+        context "when the entries are both empty" do
 
-        let(:other) do
-          described_class.new([ Band.new ])
+          let(:other) do
+            described_class.new([])
+          end
+
+          it "returns true" do
+            expect(enumerable === other).to be true
+          end
         end
 
-        it "returns false" do
-          expect(enumerable === other).to be false
+        context "when the entries are not equal" do
+
+          let(:other) do
+            described_class.new([ Band.new ])
+          end
+
+          it "returns false" do
+            expect(enumerable === other).to be false
+          end
         end
       end
     end
+
+    context 'enumerable' do
+      let(:enumerable) do
+        described_class.new(data)
+      end
+
+      include_examples 'standard library-compatible enumerable'
+    end
+
+    context 'Array instance' do
+      let(:enumerable) do
+        data
+      end
+
+      include_examples 'standard library-compatible enumerable'
+    end
   end
 
   describe "#<<" do