[Fix #247] Fix an incorrect auto-correct for Performance/MapCompact

Fixes #247. This PR fixes an incorrect auto-correct for `Performance/MapCompact` when using multi-line trailing dot method calls.
rubocop · May 20, 2021 · e1b1316 · e1b1316
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## master (unreleased)
 
+### Bug fixes
+
+* [#247](https://github.com/rubocop/rubocop-performance/issues/247): Fix an incorrect auto-correct for `Performance/MapCompact` when using multi-line trailing dot method calls. ([@koic][])
+
 ### Changes
 
 * [#245](https://github.com/rubocop/rubocop-performance/issues/245): Mark `Performance/DeletePrefix` and `Performance/DeleteSuffix` as unsafe. ([@koic][])

diff --git a/lib/rubocop/cop/performance/map_compact.rb b/lib/rubocop/cop/performance/map_compact.rb
@@ -56,23 +56,24 @@ def on_send(node)
 
           add_offense(range) do |corrector|
             corrector.replace(map_node.loc.selector, 'filter_map')
-            corrector.remove(compact_loc.dot)
-            corrector.remove(compact_method_range(node))
+            remove_compact_method(corrector, node)
           end
         end
 
         private
 
-        def compact_method_range(compact_node)
+        def remove_compact_method(corrector, compact_node)
           chained_method = compact_node.parent
           compact_method_range = compact_node.loc.selector
 
           if compact_node.multiline? && chained_method&.loc.respond_to?(:selector) &&
              !invoke_method_after_map_compact_on_same_line?(compact_node, chained_method)
-            range_by_whole_lines(compact_method_range, include_final_newline: true)
+            compact_method_range = range_by_whole_lines(compact_method_range, include_final_newline: true)
           else
-            compact_method_range
+            corrector.remove(compact_node.loc.dot)
           end
+
+          corrector.remove(compact_method_range)
         end
 
         def invoke_method_after_map_compact_on_same_line?(compact_node, chained_method)

diff --git a/spec/rubocop/cop/performance/map_compact_spec.rb b/spec/rubocop/cop/performance/map_compact_spec.rb
@@ -73,6 +73,22 @@
       RUBY
     end
 
+    it 'registers an offense when using `map.compact.first` with multi-line trailing dot method calls' do
+      expect_offense(<<~RUBY)
+        collection.
+          map { |item| item.do_something }.
+          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Use `filter_map` instead.
+          compact.
+          first
+      RUBY
+
+      expect_correction(<<~RUBY)
+        collection.
+          filter_map { |item| item.do_something }.
+          first
+      RUBY
+    end
+
     it 'registers an offense when using `map.compact.first` and there is a line break after `map.compact`' do
       expect_offense(<<~RUBY)
         collection.map { |item| item.do_something }.compact