[Fix rubocop#504] Rails/FindBy being wrongly triggered on non Active …

…Record methods

lib/rubocop/cop/rails/find_by.rb

@@ -31,7 +31,12 @@ class FindBy < Base
         MSG = 'Use `find_by` instead of `where.%<method>s`.'
         RESTRICT_ON_SEND = %i[first take].freeze
 
+        def_node_matcher :preceding_where?, <<~PATTERN
+          (send ({send csend} _ :where ...) {:first :take})
+        PATTERN
+
         def on_send(node)
+          return unless preceding_where?(node)
           return if ignore_where_first? && node.method?(:first)
 
           range = range_between(node.receiver.loc.selector.begin_pos, node.loc.selector.end_pos)

spec/rubocop/cop/rails/find_by_spec.rb

@@ -55,4 +55,24 @@
       expect_no_corrections
     end
   end
+
+  context 'when receiver is not an Active Record' do
+    context 'when method is Array#take' do
+      it 'does not register an offence' do
+        expect_no_offenses(<<~RUBY)
+          array = Array.new(1) { rand }
+          array.compact.take
+        RUBY
+      end
+    end
+
+    context 'when method is Array#first' do
+      it 'does not register an offence' do
+        expect_no_offenses(<<~RUBY)
+          array = Array.new(1) { rand }
+          array.compact.first
+        RUBY
+      end
+    end
+  end
 end