Fix Enumerable#sole when element is a tuple

Fix rails#55807

Author: olivier-thatch

activesupport/CHANGELOG.md

@@ -1,3 +1,7 @@
+*   Fix `Enumerable#sole` to return the full tuple instead of just the first element of the tuple.
+
+    *Olivier Bellone*
+
 *   Fix parallel tests hanging when worker processes die abruptly.
 
     Previously, if a worker process was killed (e.g., OOM killed, `kill -9`) during parallel

activesupport/lib/active_support/core_ext/enumerable.rb

@@ -212,12 +212,12 @@ def sole
     result = nil
     found = false
 
-    each do |element|
+    each do |*element|
       if found
         raise SoleItemExpectedError, "multiple items found"
       end
 
-      result = element
+      result = element.size == 1 ? element[0] : element
       found = true
     end
 

activesupport/test/core_ext/enumerable_test.rb

@@ -401,6 +401,26 @@ def test_sole
     assert_raise(expected_raise) { GenericEnumerable.new(1..).sole }
   end
 
+  def test_sole_returns_same_value_as_first_for_tuples
+    enum = Enumerator.new(1) { |yielder| yielder.yield(1, "one") }
+    assert_equal [1, "one"], enum.sole
+    assert_equal enum.first, enum.sole
+  end
+
+  class KeywordYielder
+    include Enumerable
+
+    def each
+      yield 1, two: 3
+    end
+  end
+
+  def test_sole_keyword_arguments
+    yielder = KeywordYielder.new
+    assert_equal [1, { two: 3 }], yielder.sole
+    assert_equal yielder.first, yielder.sole
+  end
+
   def test_doesnt_bust_constant_cache
     skip "Only applies to MRI" unless defined?(RubyVM.stat)