[Fix rubocop#8835] Fix an incorrect autocorrect for `Style/RedundantI…

…nterpolation`

Fixes rubocop#8835.

This PR fixes an incorrect autocorrect for `Style/RedundantInterpolation`
when using string interpolation for non-operator methods.

CHANGELOG.md

@@ -20,6 +20,7 @@
 * [#8807](https://github.com/rubocop-hq/rubocop/pull/8807): Fix a false positive for `Style/RedundantCondition` when using assignment by hash key access. ([@koic][])
 * [#8848](https://github.com/rubocop-hq/rubocop/issues/8848): Fix a false positive for `Style/CombinableLoops` when using the same method with different arguments. ([@dvandersluis][])
 * [#8843](https://github.com/rubocop-hq/rubocop/issues/8843): Fix an incorrect autocorrect for `Lint/AmbiguousRegexpLiteral` when sending method to regexp literal receiver. ([@koic][])
+* [#8835](https://github.com/rubocop-hq/rubocop/issues/8835): Fix an incorrect autocorrect for `Style/RedundantInterpolation` when using string interpolation for non-operator methods. ([@koic][])
 
 ### Changes
 

lib/rubocop/cop/style/redundant_interpolation.rb

@@ -51,7 +51,12 @@ def single_interpolation?(node)
         end
 
         def single_variable_interpolation?(node)
-          node.children.one? && variable_interpolation?(node.children.first)
+          return false unless node.children.one?
+
+          first_child = node.children.first
+
+          variable_interpolation?(first_child) ||
+            first_child.send_type? && !first_child.operator_method?
         end
 
         def interpolation?(node)

spec/rubocop/cop/style/redundant_interpolation_spec.rb

@@ -157,6 +157,28 @@
     RUBY
   end
 
+  it 'registers an offense for "#{number}"' do
+    expect_offense(<<~'RUBY')
+      "#{number}"
+      ^^^^^^^^^^^ Prefer `to_s` over string interpolation.
+    RUBY
+
+    expect_correction(<<~'RUBY')
+      number.to_s
+    RUBY
+  end
+
+  it 'registers an offense for "#{do_something(42)}"' do
+    expect_offense(<<~'RUBY')
+      "#{do_something(42)}"
+      ^^^^^^^^^^^^^^^^^^^^^ Prefer `to_s` over string interpolation.
+    RUBY
+
+    expect_correction(<<~'RUBY')
+      do_something(42).to_s
+    RUBY
+  end
+
   it 'registers an offense for "#{var}"' do
     expect_offense(<<~'RUBY')
       var = 1; "#{var}"