Singularize model name.

app/models/event.rb

@@ -395,6 +395,6 @@ class Event < ActiveRecord::Base
     # Note the call to .available? is due to earlier migrations
     # that would otherwise conflict with the call to .track
     # (because the table does not exist yet).
-    UserInteractedProjects.track(self) if UserInteractedProjects.available?
+    UserInteractedProject.track(self) if UserInteractedProject.available?
   end
 end

app/models/user_interacted_project.rb

@@ -1,4 +1,4 @@
-class UserInteractedProjects < ActiveRecord::Base
+class UserInteractedProject < ActiveRecord::Base
   belongs_to :user
   belongs_to :project
 

spec/models/event_spec.rb

@@ -53,15 +53,15 @@ describe Event do
     describe 'after_create :track_user_interacted_projects' do
       let(:event) { build(:push_event, project: project, author: project.owner) }
 
-      it 'passes event to UserInteractedProjects.track' do
-        expect(UserInteractedProjects).to receive(:available?).and_return(true)
-        expect(UserInteractedProjects).to receive(:track).with(event)
+      it 'passes event to UserInteractedProject.track' do
+        expect(UserInteractedProject).to receive(:available?).and_return(true)
+        expect(UserInteractedProject).to receive(:track).with(event)
         event.save
       end
 
-      it 'does not call UserInteractedProjects.track if its not yet available' do
-        expect(UserInteractedProjects).to receive(:available?).and_return(false)
-        expect(UserInteractedProjects).not_to receive(:track)
+      it 'does not call UserInteractedProject.track if its not yet available' do
+        expect(UserInteractedProject).to receive(:available?).and_return(false)
+        expect(UserInteractedProject).not_to receive(:track)
         event.save
       end
     end

spec/models/user_interacted_project_spec.rb

@@ -1,6 +1,6 @@
 require 'spec_helper'
 
-describe UserInteractedProjects do
+describe UserInteractedProject do
   describe '.track' do
     subject { described_class.track(event) }
     let(:event) { build(:event) }