AO3-5336 Fix OTP filter to account for synonymous relationships (#3246)

app/models/work.rb

@@ -1578,8 +1578,11 @@ def crossover
   end
 
   # Does this work have only one relationship tag?
+  # (not counting synonyms)
   def otp
-    relationships.count == 1
+    return true if relationships.count == 1
+    all_without_syns = relationships.map { |r| r.merger ? r.merger : r }.uniq.compact
+    all_without_syns.count == 1
   end
 
   # Quick and dirty categorization of the most obvious stuff

spec/models/work_spec.rb

@@ -102,6 +102,57 @@
     end
   end
 
+  describe "#otp" do
+    it "is not otp with no relationship" do
+      work = create(:work)
+      expect(work.relationships).to be_empty
+      expect(work.otp).to be_falsy
+    end
+
+    it "is otp with only one relationship" do
+      rel = create(:relationship, name: "asushin")
+      work = create(:work, relationships: [rel])
+      expect(work.otp).to be_truthy
+    end
+
+    it "is otp with one canonical relationship and one of its synonyms" do
+      rel = create(:canonical_relationship, name: "kawoshin")
+      syn = create(:relationship, name: "shinkawo", merger: rel)
+      work = create(:work, relationships: [rel, syn])
+      expect(work.otp).to be_truthy
+    end
+
+    it "is otp with multiple synonyms of the same canonical relationship" do
+      rel = create(:canonical_relationship, name: "kawoshin")
+      syn1 = create(:relationship, name: "shinkawo", merger: rel)
+      syn2 = create(:relationship, name: "kaworu/shinji", merger: rel)
+      work = create(:work, relationships: [syn1, syn2])
+      expect(work.otp).to be_truthy
+    end
+
+    it "is not otp with unrelated relationships, one of which is canonical" do
+      ships = [create(:relationship, name: "shinrei"), create(:canonical_relationship, name: "asurei")]
+      work = create(:work, relationships: ships)
+      expect(work.otp).to be_falsy
+    end
+
+    it "is not otp with unrelated relationships" do
+      ships = [create(:relationship, name: "asushin"), create(:relationship, name: "asurei")]
+      work = create(:work, relationships: ships)
+      expect(work.otp).to be_falsy
+    end
+
+    it "is not otp with related relationships that are not synonyms" do
+      rel1 = create(:canonical_relationship, name: "shinrei")
+      rel2 = create(:canonical_relationship, name: "asurei")
+      parent = create(:canonical_relationship)
+      parent.update_attribute(:sub_tag_string, "#{rel1.name},#{rel2.name}")
+
+      work = create(:work, relationships: [rel1, rel2])
+      expect(work.otp).to be_falsy
+    end
+  end
+
   describe "#set_author_sorting" do
     let(:work) { build(:work) }