Prevent duplicate ids

.circleci/config.yml

@@ -17,6 +17,9 @@ jobs:
       - run:
           name: Rspec tests
           command: bundle exec rspec --color --require spec_helper spec
+      - run:
+          name: Duplicate rule check
+          command: bundle exec ./bin/cfn_nag_rules
   end_to_end_test:
     docker:
       - image: circleci/ruby:2.5.5-browsers

lib/cfn-nag/custom_rules/ElastiCacheReplicationGroupTransitEncryptionRule.rb

@@ -13,7 +13,7 @@ def rule_type
   end
 
   def rule_id
-    'F24'
+    'F33'
   end
 
   def audit_impl(cfn_model)

lib/cfn-nag/result_view/rules_view.rb

@@ -8,10 +8,24 @@ def emit(rule_registry, profile)
     puts
     puts 'FAILING VIOLATIONS:'
     emit_failings rule_registry.failings, profile
+
+    if rule_registry.duplicate_ids?
+      emit_duplicates(rule_registry.duplicate_ids)
+      exit 1
+    end
   end
 
   private
 
+  def emit_duplicates(duplicates)
+    duplicates.each do |info|
+      puts '------------------'.red
+      puts "Rule ID conflict detected for #{info[:id]}.".red
+      puts "New rule: #{info[:new_message]}".red
+      puts "Registered rule: #{info[:registered_message]}".red
+    end
+  end
+
   def emit_warnings(warnings, profile)
     warnings.sort { |left, right| sort_id(left, right) }.each do |warning|
       if profile.nil?

lib/cfn-nag/rule_registry.rb

@@ -3,10 +3,15 @@
 require_relative 'rule_definition'
 
 class RuleRegistry
-  attr_reader :rules
+  attr_reader :rules, :duplicate_ids
 
   def initialize
     @rules = []
+    @duplicate_ids = []
+  end
+
+  def duplicate_ids?
+    @duplicate_ids.count.positive?
   end
 
   def definition(id:,
@@ -20,7 +25,11 @@ def definition(id:,
     if existing_def.nil?
       add_rule rule_definition
     else
-      existing_def
+      @duplicate_ids << {
+        id: id,
+        new_message: message,
+        registered_message: existing_def.message
+      }
     end
   end
 

spec/end_to_end/cfn_nag_rules/rules_spec.rb

@@ -15,4 +15,41 @@
       expect(failure_rule_count).not_to eq 0
     end
   end
+
+  context 'detecting a duplicate rule id' do
+    before(:all) do
+      @duplicate_rule = 'lib/cfn-nag/custom_rules/DuplicateRule.rb'
+      duplicate_rule_content = <<-CONTENT
+      require 'cfn-nag/violation'
+      require_relative 'base'
+
+      class DuplicateRule < BaseRule
+        def rule_text
+          'Example duplicate rule'
+        end
+
+        def rule_type
+          Violation::FAILING_VIOLATION
+        end
+
+        def rule_id
+          'F1'
+        end
+
+        def audit_impl(cfn_model); end
+      end
+CONTENT
+      File.open(@duplicate_rule, 'w') {|f| f.write(duplicate_rule_content) }
+      @stdout,@stderr,@status = Open3.capture3("bundle exec ./bin/cfn_nag_rules")
+    end
+
+    after(:all) do
+      File.delete(@duplicate_rule)
+    end
+
+    it 'blah' do
+      puts @status.exitstatus
+      expect(@status.exitstatus).to eq 1
+    end
+  end
 end

spec/rule_registry_spec.rb

@@ -17,13 +17,22 @@
         ]
 
         expect(rule_registry.rules).to eq expected_rules
+        expect(rule_registry.duplicate_ids?).to be false
 
         # add a dupe
         rule_registry.definition(id: 'F444',
                                  type: RuleDefinition::WARNING,
-                                 message: 'you have been warned!!')
+                                 message: 'you have been warned!! dupe')
+
+        expected_duplicate = {
+          id: 'F444',
+          new_message: 'you have been warned!! dupe',
+          registered_message: 'you have been warned!!'
+        }
 
         expect(rule_registry.rules).to eq expected_rules
+        expect(rule_registry.duplicate_ids?).to be true
+        expect(rule_registry.duplicate_ids.first).to eq expected_duplicate
       end
     end
   end