Merge pull request #1038 from fatkodima/fix-unique_validation_without_index-empty-schema

Fix an error for `UniqueValidationWithoutIndex` when `db/schema.rb` is empty

Author: koic

changelog/fix_error_for_unique_validation_without_index_when_schema_empty.md

@@ -0,0 +1 @@
+* [#1036](https://github.com/rubocop/rubocop-rails/issues/1036): Fix an error for `UniqueValidationWithoutIndex` when `db/schema.rb` is empty. ([@fatkodima][])

lib/rubocop/rails/schema_loader.rb

@@ -43,7 +43,7 @@ def load!(target_ruby_version)
         return unless path
 
         ast = parse(path, target_ruby_version)
-        Schema.new(ast)
+        Schema.new(ast) if ast
       end
 
       def parse(path, target_ruby_version)

spec/rubocop/cop/rails/unique_validation_without_index_spec.rb

@@ -690,5 +690,17 @@ module User
         RUBY
       end
     end
+
+    context 'when db/schema.rb file is empty' do
+      let(:schema) { '' }
+
+      it 'does not register an offense' do
+        expect_no_offenses(<<~RUBY)
+          class User
+            validates :account, uniqueness: true
+          end
+        RUBY
+      end
+    end
   end
 end