[Fix #238] Fix an incorrect auto-correct for Performance/MapCompact

Fixes #238.

This PR fixes an incorrect auto-correct for `Performance/MapCompact`
when invoking a method after `map { ... }.compact` on the same line.

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## master (unreleased)
 
+### Bug fixes
+
+* [#238](https://github.com/rubocop/rubocop-performance/issues/238): Fix an incorrect auto-correct for `Performance/MapCompact` when invoking a method after `map { ... }.compact` on the same line. ([@koic][])
+
 ## 1.11.1 (2021-05-02)
 
 ### Bug fixes

lib/rubocop/cop/performance/map_compact.rb

@@ -63,14 +63,20 @@ def on_send(node)
         private
 
         def compact_method_range(compact_node)
+          chained_method = compact_node.parent
           compact_method_range = compact_node.loc.selector
 
-          if compact_node.multiline?
+          if compact_node.multiline? &&
+             chained_method && !invoke_method_after_map_compact_on_same_line?(compact_node, chained_method)
             range_by_whole_lines(compact_method_range, include_final_newline: true)
           else
             compact_method_range
           end
         end
+
+        def invoke_method_after_map_compact_on_same_line?(compact_node, chained_method)
+          compact_node.loc.selector.line == chained_method.loc.selector.line
+        end
       end
     end
   end

spec/rubocop/cop/performance/map_compact_spec.rb

@@ -86,6 +86,32 @@
       RUBY
     end
 
+    it 'registers an offense when using `map { ... }.compact`' do
+      expect_offense(<<~RUBY)
+        collection.map { |item|
+                   ^^^^^^^^^^^^ Use `filter_map` instead.
+        }.compact
+      RUBY
+
+      expect_correction(<<~RUBY)
+        collection.filter_map { |item|
+        }
+      RUBY
+    end
+
+    it 'registers an offense when invoking a method after `map { ... }.compact`' do
+      expect_offense(<<~RUBY)
+        collection.map { |item|
+                   ^^^^^^^^^^^^ Use `filter_map` instead.
+        }.compact.do_something
+      RUBY
+
+      expect_correction(<<~RUBY)
+        collection.filter_map { |item|
+        }.do_something
+      RUBY
+    end
+
     it 'does not register an offense when using `collection.map(&:do_something).compact!`' do
       expect_no_offenses(<<~RUBY)
         collection.map(&:do_something).compact!