1 files changed, 50 insertions, 0 deletions
diff --git a/test/ruby/test_stringchar.rb b/test/ruby/test_stringchar.rb
index 943b656510..34934e87bd 100644
--- a/test/ruby/test_stringchar.rb
+++ b/test/ruby/test_stringchar.rb
@@ -113,4 +113,54 @@ EOS
     }
     assert_equal(0, a.size)
   end
+
+  def test_bang
+    s = "aBc"
+    s.upcase
+    assert_equal("aBc", s)
+    s.upcase!
+    assert_equal("ABC", s)
+
+    s = "aBc"
+    s.downcase
+    assert_equal("aBc", s)
+    s.downcase!
+    assert_equal("abc", s)
+
+    s = "aBc"
+    s.swapcase
+    assert_equal("aBc", s)
+    s.swapcase!
+    assert_equal("AbC", s)
+
+    s = "aBc"
+    s.capitalize
+    assert_equal("aBc", s)
+    s.capitalize!
+    assert_equal("Abc", s)
+
+    s = "aBc"
+    s.tr("a-z", "A-Z")
+    assert_equal("aBc", s)
+    s.tr!("a-z", "A-Z")
+    assert_equal("ABC", s)
+
+    s = "aaBBcc"
+    s.tr_s("a-z", "A-Z")
+    assert_equal("aaBBcc", s)
+    s.tr_s!("a-z", "A-Z")
+    assert_equal("ABBC", s)
+
+    s = "aaBBcc"
+    s.squeeze("a-z")
+    assert_equal("aaBBcc", s)
+    s.squeeze!("a-z")
+    assert_equal("aBBc", s)
+
+    s = "aaBBcc"
+    s.delete("a-z")
+    assert_equal("aaBBcc", s)
+    s.delete!("a-z")
+    assert_equal("BB", s)
+  end
 end