Merge pull request #423 from koic/fix_false_positives_for_performance…

…_times_map

[Fix #421] Fix false positives for `Performance/TimesMap`

lib/rubocop/cop/performance/times_map.rb

@@ -50,6 +50,8 @@ def on_block(node)
 
         def check(node)
           times_map_call(node) do |map_or_collect, count|
+            next unless handleable_receiver?(node)
+
             add_offense(node, message: message(map_or_collect, count)) do |corrector|
               replacement = "Array.new(#{count.source}#{map_or_collect.arguments.map { |arg| ", #{arg.source}" }.join})"
 
@@ -58,6 +60,13 @@ def check(node)
           end
         end
 
+        def handleable_receiver?(node)
+          receiver = node.receiver.receiver
+          return true if receiver.literal? && (receiver.int_type? || receiver.float_type?)
+
+          node.receiver.dot?
+        end
+
         def message(map_or_collect, count)
           template = if count.literal?
                        "#{MESSAGE}."

spec/rubocop/cop/performance/times_map_spec.rb

@@ -29,6 +29,48 @@
         end
       end
 
+      context 'with a block with safe navigation call for integer literal' do
+        it 'registers an offense and corrects' do
+          expect_offense(<<~RUBY, method: method)
+            42&.times&.#{method} { |i| i.to_s }
+            ^^^^^^^^^^^^{method}^^^^^^^^^^^^^^^ Use `Array.new(42)` with a block instead of `.times.#{method}`.
+          RUBY
+        end
+      end
+
+      context 'with a block with safe navigation call for float literal' do
+        it 'registers an offense and corrects' do
+          expect_offense(<<~RUBY, method: method)
+            4.2&.times&.#{method} { |i| i.to_s }
+            ^^^^^^^^^^^^^{method}^^^^^^^^^^^^^^^ Use `Array.new(4.2)` with a block instead of `.times.#{method}`.
+          RUBY
+        end
+      end
+
+      context 'with a block with safe navigation call for nil literal' do
+        it 'does not register an offense' do
+          expect_no_offenses(<<~RUBY, method: method)
+            nil&.times&.#{method} { |i| i.to_s }
+          RUBY
+        end
+      end
+
+      context 'with a block with safe navigation call for local variable' do
+        it 'does not register an offense' do
+          expect_no_offenses(<<~RUBY, method: method)
+            nullable&.times&.#{method} { |i| i.to_s }
+          RUBY
+        end
+      end
+
+      context 'with a block with safe navigation call for instance variable' do
+        it 'does not register an offense' do
+          expect_no_offenses(<<~RUBY, method: method)
+            @nullable&.times&.#{method} { |i| i.to_s }
+          RUBY
+        end
+      end
+
       context 'for non-literal receiver' do
         it 'registers an offense' do
           expect_offense(<<~RUBY, method: method)