[Fix #3918] Prevent Rails/EnumUniqueness from breaking on a non-lit…

…eral hash value

This cop would break on any enum hash that did not have a literal value.
This change fixes that.

CHANGELOG.md

@@ -6,6 +6,7 @@
 
 * [#3911](https://github.com/bbatsov/rubocop/issues/3911): Prevent a crash in `Performance/RegexpMatch` cop with module definition. ([@pocke][])
 * [#3908](https://github.com/bbatsov/rubocop/issues/3908): Prevent `Style/AlignHash` from breaking on a keyword splat when using enforced `table` style. ([@drenmi][])
+* [#3918](https://github.com/bbatsov/rubocop/issues/3918): Prevent `Rails/EnumUniqueness` from breaking on a non-literal hash value. ([@drenmi][])
 
 ## 0.47.0 (2017-01-16)
 

lib/rubocop/cop/rails/enum_uniqueness.rb

@@ -23,7 +23,7 @@ class EnumUniqueness < Cop
         MSG = 'Duplicate value `%s` found in `%s` enum declaration.'.freeze
 
         def_node_matcher :enum_declaration, <<-END
-          (send nil :enum (hash (pair (_ $_) $_)))
+          (send nil :enum (hash (pair (_ $_) ${array hash})))
         END
 
         def on_send(node)

spec/rubocop/cop/rails/enum_uniqueness_spec.rb

@@ -64,11 +64,37 @@
   end
 
   context 'when receiving a variable' do
-    it 'does not register an offence' do
+    it 'does not register an offense' do
       inspect_source(cop, ['var = { status: { active: 0, archived: 1 } }',
                            'enum var'])
 
       expect(cop.offenses).to be_empty
     end
   end
+
+  context 'when receiving a hash without literal values' do
+    context 'when value is a variable' do
+      it 'does not register an offense' do
+        inspect_source(cop, 'enum status: statuses')
+
+        expect(cop.offenses).to be_empty
+      end
+    end
+
+    context 'when value is a method chain' do
+      it 'does not register an offense' do
+        inspect_source(cop, 'enum status: User.statuses.keys')
+
+        expect(cop.offenses).to be_empty
+      end
+    end
+
+    context 'when value is a constant' do
+      it 'does not register an offense' do
+        inspect_source(cop, 'enum status: STATUSES')
+
+        expect(cop.offenses).to be_empty
+      end
+    end
+  end
 end