[Fix #6822] Fix Lint/LiteralInInterpolation autocorrection for single…

… quotes (#6979)

## Current behavior:

  Doing `$ rubocop --only Lint/LiteralInInterpolation`;

  source:

  ```ruby
  x = "ABC".gsub(/(A)(B)(C)/, "D#{'\2'}F")
  "foo#{'\n'}bar"
  "this is #{'"'} silly"
  ```

  corrected to:

  ```ruby
  x = "ABC".gsub(/(A)(B)(C)/, "D\2F")
  "foo\nbar"
  "this is " silly"
  ```

  ## New behavior:

  corrected to:

  ```ruby
  x = "ABC".gsub(/(A)(B)(C)/, "D\\2F")
  "foo\\nbar"
  "this is \" silly"
  ```

CHANGELOG.md

@@ -27,6 +27,7 @@
 * [#6935](https://github.com/rubocop-hq/rubocop/issues/6935): `Layout/AccessModifierIndentation` should ignore access modifiers that apply to specific methods. ([@deivid-rodriguez][])
 * [#6956](https://github.com/rubocop-hq/rubocop/issues/6956): Prevent auto-correct confliction of `Lint/Lambda` and `Lint/UnusedBlockArgument`. ([@koic][])
 * [#6915](https://github.com/rubocop-hq/rubocop/issues/6915): Fix false positive in `Style/SafeNavigation` when a modifier if is safe guarding a method call being passed to `break`, `fail`, `next`, `raise`, `return`, `throw`, and `yield`. ([@rrosenblum][])
+* [#6822](https://github.com/rubocop-hq/rubocop/issues/6822): Fix Lint/LiteralInInterpolation autocorrection for single quotes. ([@hoshinotsuyoshi][])
 * [#6985](https://github.com/rubocop-hq/rubocop/issues/6985): Fix an incorrect auto-correct for `Lint/LiteralInInterpolation` if contains array percent literal. ([@yakout][])
 
 ### Changes

lib/rubocop/cop/lint/literal_in_interpolation.rb

@@ -56,7 +56,7 @@ def autocorrected_value(node)
           when :float
             node.children.last.to_f.to_s
           when :str
-            node.children.last
+            autocorrected_value_for_string(node)
           when :sym
             autocorrected_value_for_symbol(node)
           when :array
@@ -66,6 +66,14 @@ def autocorrected_value(node)
           end
         end
 
+        def autocorrected_value_for_string(node)
+          if node.source.start_with?("'", '%q')
+            node.children.last.inspect[1..-2]
+          else
+            node.children.last
+          end
+        end
+
         def autocorrected_value_for_symbol(node)
           end_pos =
             node.loc.end ? node.loc.end.begin_pos : node.loc.expression.end_pos

spec/rubocop/cop/lint/literal_in_interpolation_spec.rb

@@ -152,4 +152,42 @@
 
   it_behaves_like('non-special string literal interpolation', %('foo'))
   it_behaves_like('non-special string literal interpolation', %("foo"))
+
+  it 'handles double quotes in single quotes when auto-correction' do
+    corrected = autocorrect_source(<<-'RUBY'.strip_indent)
+      "this is #{'"'} silly"
+    RUBY
+    expect(corrected).to eq(<<-'RUBY'.strip_indent)
+      "this is \" silly"
+    RUBY
+  end
+
+  it 'handles backslach in single quotes when auto-correction' do
+    corrected = autocorrect_source(<<-'RUBY'.strip_indent)
+      x = "ABC".gsub(/(A)(B)(C)/, "D#{'\2'}F")
+      "this is #{'\n'} silly"
+      "this is #{%q(\n)} silly"
+    RUBY
+    expect(corrected).to eq(<<-'RUBY'.strip_indent)
+      x = "ABC".gsub(/(A)(B)(C)/, "D\\2F")
+      "this is \\n silly"
+      "this is \\n silly"
+    RUBY
+  end
+
+  it 'handles backslach in double quotes when auto-correction' do
+    corrected = autocorrect_source(<<-'RUBY'.strip_indent)
+      "this is #{"\n"} silly"
+      "this is #{%(\n)} silly"
+      "this is #{%Q(\n)} silly"
+    RUBY
+    expect(corrected).to eq(<<-'RUBY'.strip_indent)
+      "this is 
+       silly"
+      "this is 
+       silly"
+      "this is 
+       silly"
+    RUBY
+  end
 end