Merge pull request #1616 from koic/fix_false_positives_in_rails_strong_parameters_expect

Fix false positives in `Rails/StrongParametersExpect`

Author: koic

changelog/fix_false_positives_for_rails_strong_parameters_expect.md

@@ -0,0 +1 @@
+* [#1616](https://github.com/rubocop/rubocop-rails/pull/1616): Fix false positives in `Rails/StrongParametersExpect` when using nil-safe conversion methods such as `to_i`, `to_s`, `to_a`, `to_f`, and `to_h` on `params[:key]`. ([@koic][])

lib/rubocop/cop/rails/strong_parameters_expect.rb

@@ -8,7 +8,7 @@ module Rails
       # In the following cases, `params[:key]` is treated as a key that is expected to be passed from the HTTP client,
       # and the cop detects it using the `expect` method.
       #
-      # - Method calls on `params[:key]` without comparison methods
+      # - Method calls on `params[:key]` without comparison methods and nil-safe conversion methods
       # - Passing `params[:key]` as an argument to finder methods that raise on missing records
       # - Strong parameter methods using `require` or `permit`
       #
@@ -54,6 +54,7 @@ class StrongParametersExpect < Base
         MSG = 'Use `%<prefer>s` instead.'
         RESTRICT_ON_SEND = %i[[] require permit].freeze
         PRESENCE_CHECK_METHODS = %i[nil? blank? present? presence].freeze
+        NIL_SAFE_CONVERSION_METHODS = %i[to_a to_f to_h to_i to_s].freeze
         RAISING_FINDER_METHODS = %i[find find_by! find_sole_by].freeze
 
         minimum_target_rails_version 8.0
@@ -131,9 +132,11 @@ def offensive_bracket_access?(node)
           return false unless parent.call_type?
 
           if parent.receiver == node
-            return false if parent.comparison_method?
+            return false if parent.comparison_method? || parent.method?(:[])
 
-            !parent.method?(:[]) && !PRESENCE_CHECK_METHODS.include?(parent.method_name)
+            method_name = parent.method_name
+
+            !PRESENCE_CHECK_METHODS.include?(method_name) && !NIL_SAFE_CONVERSION_METHODS.include?(method_name)
           else
             raising_finder_method?(parent)
           end

spec/rubocop/cop/rails/strong_parameters_expect_spec.rb

@@ -25,6 +25,36 @@
       RUBY
     end
 
+    it 'does not register an offense when using `key = params[:key].to_i`' do
+      expect_no_offenses(<<~RUBY)
+        params[:key].to_i
+      RUBY
+    end
+
+    it 'does not register an offense when using `params[:key].to_s`' do
+      expect_no_offenses(<<~RUBY)
+        params[:key].to_s
+      RUBY
+    end
+
+    it 'does not register an offense when using `params[:key].to_a`' do
+      expect_no_offenses(<<~RUBY)
+        params[:key].to_a
+      RUBY
+    end
+
+    it 'does not register an offense when using `params[:key].to_f`' do
+      expect_no_offenses(<<~RUBY)
+        params[:key].to_f
+      RUBY
+    end
+
+    it 'does not register an offense when using `params[:key].to_h`' do
+      expect_no_offenses(<<~RUBY)
+        params[:key].to_h
+      RUBY
+    end
+
     it "does not register an offense when using `params[:key] == 'value'`" do
       expect_no_offenses(<<~RUBY)
         params[:key] == 'value'