[Fix rubocop#12434] Fix a false positive for `Lint/LiteralAssignmentI…

…nCondition`

Fixes rubocop#12434.

This PR fixes a false positive for `Lint/LiteralAssignmentInCondition`
when using interpolated string or xstring literals.

changelog/fix_a_false_positive_for_lint_literal_assignment_in_condition.md

@@ -0,0 +1 @@
+* [#12434](https://github.com/rubocop/rubocop/issues/12434): Fix a false positive for `Lint/LiteralAssignmentInCondition` when using interpolated string or xstring literals. ([@koic][])

lib/rubocop/cop/lint/literal_assignment_in_condition.rb

@@ -41,7 +41,7 @@ def on_if(node)
             next unless asgn_node.loc.operator
 
             rhs = asgn_node.to_a.last
-            next if !literal?(rhs) || parallel_assignment_with_splat_operator?(rhs)
+            next if !forbidden_literal?(rhs) || parallel_assignment_with_splat_operator?(rhs)
 
             range = offense_range(asgn_node, rhs)
 
@@ -59,7 +59,9 @@ def traverse_node(node, &block)
           node.each_child_node { |child| traverse_node(child, &block) }
         end
 
-        def literal?(node)
+        def forbidden_literal?(node)
+          return false if node.dstr_type? || node.xstr_type?
+
           node.respond_to?(:literal?) && node.literal?
         end
 

spec/rubocop/cop/lint/literal_assignment_in_condition_spec.rb

@@ -9,6 +9,28 @@
     RUBY
   end
 
+  it 'registers an offense when assigning string literal to local variable in `if` condition' do
+    expect_offense(<<~RUBY)
+      if test = 'foo'
+              ^^^^^^^ Don't use literal assignment `= 'foo'` in conditional, should be `==` or non-literal operand.
+      end
+    RUBY
+  end
+
+  it 'does not register an offense when assigning interpolated string literal to local variable in `if` condition' do
+    expect_no_offenses(<<~'RUBY')
+      if test = "#{foo}"
+      end
+    RUBY
+  end
+
+  it 'does not register an offense when assigning xstring literal to local variable in `if` condition' do
+    expect_no_offenses(<<~RUBY)
+      if test = `echo 'hi'`
+      end
+    RUBY
+  end
+
   it 'registers an offense when assigning array literal to local variable in `if` condition' do
     expect_offense(<<~RUBY)
       if test = []