[Fix #1630] Fix a false positive in Rails/StrongParametersExpect

changelog/fix_false_positives_for_rails_strong_parameters_expect_with_negation.md

@@ -0,0 +1 @@
+* [#1630](https://github.com/rubocop/rubocop-rails/issues/1630): Fix a false positive in `Rails/StrongParametersExpect` when negating `params[:key]` with `!`, such as `!params[:key]`. ([@koic][])

lib/rubocop/cop/rails/strong_parameters_expect.rb

@@ -60,7 +60,7 @@ class StrongParametersExpect < Base
         # Covers presence/nil checks, nil-safe conversions and type checks, key-check methods,
         # and collection methods that imply `params[:key]` is a Hash/Array.
         IGNORED_METHODS = %i[
-          blank? compact compact! compact_blank compact_blank! deep_merge deep_merge!
+          ! blank? compact compact! compact_blank compact_blank! deep_merge deep_merge!
           delete delete_if dig each except exclude? extract! fetch has_key? has_value?
           include? instance_of? is_a? keep_if key? keys kind_of? member? merge merge!
           nil? presence present? reverse_merge reverse_merge! slice stringify_keys

spec/rubocop/cop/rails/strong_parameters_expect_spec.rb

@@ -207,6 +207,18 @@
       RUBY
     end
 
+    it 'does not register an offense when using `!params[:key]`' do
+      expect_no_offenses(<<~RUBY)
+        !params[:key]
+      RUBY
+    end
+
+    it 'does not register an offense when using `condition && !params[:key]`' do
+      expect_no_offenses(<<~RUBY)
+        condition && !params[:key]
+      RUBY
+    end
+
     it 'does not register an offense when using `params[:key].blank?`' do
       expect_no_offenses(<<~RUBY)
         params[:key].blank?