[BC-26568] Add rubocop warning for the use of Bugsnag

config/default.yml

@@ -76,3 +76,9 @@ BugcrowdCops/PreventReindexFullESDocumentCop:
   Enabled: true
   Include:
     - 'app/**/*.rb'
+
+BugcrowdCops/PreventBugsnagUsage:
+  Enabled: true
+  Include:
+    - 'app/**/*.rb'
+    - 'lib/**/*.rb'

lib/rubocop/cop/bugcrowd/prevent_bugsnag_usage.rb

@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module Bugcrowd
+      class PreventBugsnagUsage < RuboCop::Cop::Base
+        MSG = 'Do not use Bugsnag in the codebase, as its integration has been removed. ' \
+              'Use ErrorTrackingService for reporting errors.'
+
+        def on_send(node)
+          add_offense(node, message: MSG) if node.receiver&.const_name == 'Bugsnag'
+        end
+      end
+    end
+  end
+end

lib/rubocop/cop/bugcrowd_cops.rb

@@ -38,3 +38,4 @@
 require_relative 'bugcrowd/no_event_deprecated_publish'
 require_relative 'bugcrowd/sidekiq_testing_inline'
 require_relative 'bugcrowd/prevent_reindex_full_es_document_cop'
+require_relative 'bugcrowd/prevent_bugsnag_usage'

spec/rubocop/cop/bugcrowd/prevent_bugsnag_usage_spec.rb

@@ -0,0 +1,49 @@
+# frozen_string_literal: true
+
+RSpec.describe RuboCop::Cop::Bugcrowd::PreventBugsnagUsage, :config do
+  subject(:cop) { described_class.new(config) }
+
+  let(:message) do
+    'Do not use Bugsnag in the codebase, as its integration has been removed. ' \
+    'Use ErrorTrackingService for reporting errors.'
+  end
+
+  it 'registers an offense when Bugsnag is used' do
+    expect_offense(<<~RUBY)
+      Bugsnag.error('Error')
+      ^^^^^^^^^^^^^^^^^^^^^^ #{message}
+    RUBY
+  end
+
+  it 'registers an offense when Bugsnag.notify is used' do
+    expect_offense(<<~RUBY)
+      Bugsnag.notify('Error')
+      ^^^^^^^^^^^^^^^^^^^^^^^ #{message}
+    RUBY
+  end
+
+  it 'does not register an offense for ErrorTrackingService' do
+    expect_no_offenses(<<~RUBY)
+      ErrorTrackingService.notify('Error')
+    RUBY
+  end
+
+  it 'does not register an offense for unrelated constants' do
+    expect_no_offenses(<<~RUBY)
+      SomeOtherService.notify('Error')
+    RUBY
+  end
+
+  it 'does not register an offense for lowercase bugsnag' do
+    expect_no_offenses(<<~RUBY)
+      bugsnag.error('Error')
+    RUBY
+  end
+
+  it 'does not register an offense for local variable named Bugsnag' do
+    expect_no_offenses(<<~RUBY)
+      bugsnag = SomeService.new
+      bugsnag.error('Error')
+    RUBY
+  end
+end