Add `assert_same` and `assert_not_same`

test/assert.rb

@@ -124,6 +124,32 @@ def assert_not_equal(arg1, arg2 = nil, arg3 = nil)
   assert_false(exp == act, msg, diff)
 end
 
+def assert_same(arg1, arg2 = nil, arg3 = nil)
+  if block_given?
+    exp, act, msg = arg1, yield, arg2
+  else
+    exp, act, msg = arg1, arg2, arg3
+  end
+
+  msg ||= "Expected #{act.inspect} to be the same object as #{exp.inspect}"
+  diff = "    Expected: #{exp.inspect} (class=#{exp.class}, oid=#{exp.__id__})\n" +
+         "      Actual: #{act.inspect} (class=#{act.class}, oid=#{act.__id__})"
+  assert_true(exp.equal?(act), msg, diff)
+end
+
+def assert_not_same(arg1, arg2 = nil, arg3 = nil)
+  if block_given?
+    exp, act, msg = arg1, yield, arg2
+  else
+    exp, act, msg = arg1, arg2, arg3
+  end
+
+  msg ||= "Expected #{act.inspect} to not be the same object as #{exp.inspect}"
+  diff = "    Expected: #{exp.inspect} (class=#{exp.class}, oid=#{exp.__id__})\n" +
+         "      Actual: #{act.inspect} (class=#{act.class}, oid=#{act.__id__})"
+  assert_false(exp.equal?(act), msg, diff)
+end
+
 def assert_nil(obj, msg = nil)
   msg = "Expected #{obj.inspect} to be nil" unless msg
   diff = assertion_diff(nil, obj)

test/t/proc.rb

@@ -157,7 +157,7 @@ assert('&obj call to_proc if defined') do
   def mock(&b)
     b
   end
-  assert_equal pr.object_id, mock(&pr).object_id
+  assert_same pr, mock(&pr)
   assert_equal pr, mock(&pr)
 
   obj = Object.new

test/t/string.rb

@@ -579,7 +579,7 @@ assert('String#sub', '15.2.10.5.36') do
   str = "abc"
   miss = str.sub("X", "Z")
   assert_equal str, miss
-  assert_not_equal str.object_id, miss.object_id
+  assert_not_same str, miss
 
   a = []
   assert_equal '.abc', "abc".sub("") { |i| a << i; "." }