1 files changed, 47 insertions, 0 deletions
diff --git a/rubocop/cop/inject_enterprise_edition_module.rb b/rubocop/cop/inject_enterprise_edition_module.rb
new file mode 100644
index 00000000000..c8b8aca51ab
--- /dev/null
+++ b/rubocop/cop/inject_enterprise_edition_module.rb
@@ -0,0 +1,47 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    # Cop that blacklists the injecting of EE specific modules anywhere but on
+    # the last line of a file. Injecting a module in the middle of a file will
+    # cause merge conflicts, while placing it on the last line will not.
+    class InjectEnterpriseEditionModule < RuboCop::Cop::Cop
+      MSG = 'Injecting EE modules must be done on the last line of this file' \
+        ', outside of any class or module definitions'
+
+      METHODS = Set.new(%i[include extend prepend]).freeze
+
+      def_node_matcher :ee_const?, <<~PATTERN
+        (const (const _ :EE) _)
+      PATTERN
+
+      def on_send(node)
+        return unless METHODS.include?(node.children[1])
+        return unless ee_const?(node.children[2])
+
+        line = node.location.line
+        buffer = node.location.expression.source_buffer
+        last_line = buffer.last_line
+
+        # Parser treats the final newline (if present) as a separate line,
+        # meaning that a simple `line < last_line` would yield true even though
+        # the expression is the last line _of code_.
+        last_line -= 1 if buffer.source.end_with?("\n")
+
+        add_offense(node) if line < last_line
+      end
+
+      # Automatically correcting these offenses is not always possible, as
+      # sometimes code needs to be refactored to make this work. As such, we
+      # only allow developers to easily blacklist existing offenses.
+      def autocorrect(node)
+        lambda do |corrector|
+          corrector.insert_after(
+            node.source_range,
+            " # rubocop: disable #{cop_name}"
+          )
+        end
+      end
+    end
+  end
+end