[ruby/singleton] Simplify the implementation

(https://github.com/ruby/singleton/pull/7)

Remove `__init__` and move logic to `included`.

1 files changed, 11 insertions, 0 deletions

diff --git a/test/test_singleton.rb b/test/test_singleton.rb
index b3c48bb5f5..b08972b9d5 100644
--- a/test/test_singleton.rb
+++ b/test/test_singleton.rb
@@ -94,6 +94,13 @@ class TestSingleton < Test::Unit::TestCase
     assert_same a, b
   end
 
+  def test_inheritance_creates_separate_singleton
+    a = SingletonTest.instance
+    b = Class.new(SingletonTest).instance
+
+    assert_not_same a, b
+  end
+
   def test_class_level_cloning_preserves_singleton_behavior
     klass = SingletonTest.clone
 
@@ -101,4 +108,8 @@ class TestSingleton < Test::Unit::TestCase
     b = klass.instance
     assert_same a, b
   end
+
+  def test_class_level_cloning_creates_separate_singleton
+    assert_not_same SingletonTest.instance, SingletonTest.clone.instance
+  end
 end