1 files changed, 16 insertions, 18 deletions
diff --git a/test/-ext-/string/test_fstring.rb b/test/-ext-/string/test_fstring.rb
index 9b4956ecef..fcec6be543 100644
--- a/test/-ext-/string/test_fstring.rb
+++ b/test/-ext-/string/test_fstring.rb
@@ -15,19 +15,27 @@ class Test_String_Fstring < Test::Unit::TestCase
   def test_rb_enc_interned_str_autoloaded_encoding
     assert_separately([], <<~RUBY)
       require '-test-/string'
-      assert_include(Encoding::Windows_31J.inspect, 'autoload')
-      Bug::String.rb_enc_interned_str(Encoding::Windows_31J)
+      assert_include(Encoding::CESU_8.inspect, 'autoload')
+      Bug::String.rb_enc_interned_str(Encoding::CESU_8)
     RUBY
   end
 
+  def test_rb_enc_interned_str_null_encoding
+    assert_equal Encoding::ASCII_8BIT, Bug::String.rb_enc_interned_str(nil).encoding
+  end
+
   def test_rb_enc_str_new_autoloaded_encoding
     assert_separately([], <<~RUBY)
       require '-test-/string'
-      assert_include(Encoding::Windows_31J.inspect, 'autoload')
-      Bug::String.rb_enc_str_new(Encoding::Windows_31J)
+      assert_include(Encoding::CESU_8.inspect, 'autoload')
+      Bug::String.rb_enc_str_new(Encoding::CESU_8)
     RUBY
   end
 
+  def test_rb_enc_str_new_null_encoding
+    assert_equal Encoding::ASCII_8BIT, Bug::String.rb_enc_str_new(nil).encoding
+  end
+
   def test_instance_variable
     str = __method__.to_s * 3
     str.instance_variable_set(:@test, 42)
@@ -49,6 +57,10 @@ class Test_String_Fstring < Test::Unit::TestCase
     assert_raise(TypeError) {fstr.singleton_class}
   end
 
+  def test_fake_str
+    assert_equal([*"a".."z"].join(""), Bug::String.fstring_fake_str)
+  end
+
   class S < String
   end
 
@@ -57,18 +69,4 @@ class Test_String_Fstring < Test::Unit::TestCase
     str.freeze
     assert_fstring(str) {|s| assert_instance_of(S, s)}
   end
-
-  def test_shared_string_safety
-    _unused = -('a' * 30).force_encoding(Encoding::ASCII)
-    begin
-      verbose_back, $VERBOSE = $VERBOSE, nil
-      str = ('a' * 30).force_encoding(Encoding::ASCII).taint
-    ensure
-      $VERBOSE = verbose_back
-    end
-    frozen_str = Bug::String.rb_str_new_frozen(str)
-    assert_fstring(frozen_str) {|s| assert_equal(str, s)}
-    GC.start
-    assert_equal('a' * 30, str, "[Bug #16151]")
-  end
 end