[Fix rubocop#12683] Fix an incorrect autocorrect for `Style/MapCompac…

…tWithConditionalBlock`

Fixes rubocop#12683

This PR fixes an incorrect autocorrect for `Style/MapCompactWithConditionalBlock`
when using guard clause with `next` implicitly nil. It also fixes the incorrect test code.

changelog/fix_an_incorrect_autocorrect_for_style_map_compact_with_conditional_block.md

@@ -0,0 +1 @@
+* [#12683](https://github.com/rubocop/rubocop/issues/12683): Fix an incorrect autocorrect for `Style/MapCompactWithConditionalBlock` when using guard clause with `next` implicitly nil. ([@koic][])

lib/rubocop/cop/style/map_compact_with_conditional_block.rb

@@ -115,11 +115,14 @@ def truthy_branch_for_if?(node)
 
         def truthy_branch_for_guard?(node)
           if_node = node.left_sibling
+          if_branch = if_node.if_branch
+
+          return false unless if_branch.next_type?
 
           if if_node.if? || if_node.ternary?
-            if_node.else_branch.nil?
+            if_branch.arguments.any? && if_node.else_branch.nil?
           elsif if_node.unless?
-            if_node.if_branch.nil?
+            if_branch.arguments.none? && if_node.else_branch.nil?
           end
         end
 

spec/rubocop/cop/style/map_compact_with_conditional_block_spec.rb

@@ -158,33 +158,33 @@
       RUBY
     end
 
-    it 'registers an offense and corrects to `select` with guard clause of `if`' do
+    it 'registers an offense and corrects to `reject` with guard clause of `if`' do
       expect_offense(<<~RUBY)
         foo.map do |item|
-            ^^^^^^^^^^^^^ Replace `map { ... }.compact` with `select`.
+            ^^^^^^^^^^^^^ Replace `map { ... }.compact` with `reject`.
           next if item.bar?
 
           item
         end.compact
       RUBY
 
       expect_correction <<~RUBY
-        foo.select { |item| item.bar? }
+        foo.reject { |item| item.bar? }
       RUBY
     end
 
-    it 'registers an offense and corrects to `reject` with guard clause of `unless`' do
+    it 'registers an offense and corrects to `select` with guard clause of `unless`' do
       expect_offense(<<~RUBY)
         foo.map do |item|
-            ^^^^^^^^^^^^^ Replace `map { ... }.compact` with `reject`.
+            ^^^^^^^^^^^^^ Replace `map { ... }.compact` with `select`.
           next unless item.bar?
 
           item
         end.compact
       RUBY
 
       expect_correction <<~RUBY
-        foo.reject { |item| item.bar? }
+        foo.select { |item| item.bar? }
       RUBY
     end