1 files changed, 25 insertions, 19 deletions
diff --git a/spec/ruby/core/string/shared/chars.rb b/spec/ruby/core/string/shared/chars.rb
index 1f045e4530..826d403589 100644
--- a/spec/ruby/core/string/shared/chars.rb
+++ b/spec/ruby/core/string/shared/chars.rb
@@ -11,22 +11,21 @@ describe :string_chars, shared: true do
 
   it "returns self" do
     s = StringSpecs::MyString.new "hello"
-    s.send(@method){}.should equal(s)
+    s.send(@method){}.should.equal?(s)
   end
 
-
   it "is unicode aware" do
     "\303\207\342\210\202\303\251\306\222g".send(@method).to_a.should ==
       ["\303\207", "\342\210\202", "\303\251", "\306\222", "g"]
   end
 
   it "returns characters in the same encoding as self" do
-    "&%".force_encoding('Shift_JIS').send(@method).to_a.all? {|c| c.encoding.name.should == 'Shift_JIS'}
+    "&%".dup.force_encoding('Shift_JIS').send(@method).to_a.all? {|c| c.encoding.name.should == 'Shift_JIS'}
     "&%".encode('BINARY').send(@method).to_a.all? {|c| c.encoding.should == Encoding::BINARY }
   end
 
   it "works with multibyte characters" do
-    s = "\u{8987}".force_encoding("UTF-8")
+    s = "\u{8987}".dup.force_encoding("UTF-8")
     s.bytesize.should == 3
     s.send(@method).to_a.should == [s]
   end
@@ -34,19 +33,19 @@ describe :string_chars, shared: true do
   it "works if the String's contents is invalid for its encoding" do
     xA4 = [0xA4].pack('C')
     xA4.force_encoding('UTF-8')
-    xA4.valid_encoding?.should be_false
+    xA4.valid_encoding?.should == false
     xA4.send(@method).to_a.should == [xA4.force_encoding("UTF-8")]
   end
 
   it "returns a different character if the String is transcoded" do
-    s = "\u{20AC}".force_encoding('UTF-8')
-    s.encode('UTF-8').send(@method).to_a.should == ["\u{20AC}".force_encoding('UTF-8')]
+    s = "\u{20AC}".dup.force_encoding('UTF-8')
+    s.encode('UTF-8').send(@method).to_a.should == ["\u{20AC}".dup.force_encoding('UTF-8')]
     s.encode('iso-8859-15').send(@method).to_a.should == [[0xA4].pack('C').force_encoding('iso-8859-15')]
-    s.encode('iso-8859-15').encode('UTF-8').send(@method).to_a.should == ["\u{20AC}".force_encoding('UTF-8')]
+    s.encode('iso-8859-15').encode('UTF-8').send(@method).to_a.should == ["\u{20AC}".dup.force_encoding('UTF-8')]
   end
 
   it "uses the String's encoding to determine what characters it contains" do
-    s = "\u{24B62}"
+    s = +"\u{24B62}"
 
     s.force_encoding('UTF-8').send(@method).to_a.should == [
       s.force_encoding('UTF-8')
@@ -64,17 +63,24 @@ describe :string_chars, shared: true do
     ]
   end
 
-  ruby_version_is ''...'2.7' do
-    it "taints resulting strings when self is tainted" do
-      str = "hello"
+  it "returns individual chars for dummy encodings" do
+    "ab".dup.force_encoding(Encoding::UTF_7).send(@method).to_a.should == [
+      "\x61".dup.force_encoding(Encoding::UTF_7),
+      "\x62".dup.force_encoding(Encoding::UTF_7)
+    ]
 
-      str.send(@method) do |x|
-        x.should_not.tainted?
-      end
+    "abcd".dup.force_encoding(Encoding::UTF_16).send(@method).to_a.should == [
+      "\x61".dup.force_encoding(Encoding::UTF_16),
+      "\x62".dup.force_encoding(Encoding::UTF_16),
+      "\x63".dup.force_encoding(Encoding::UTF_16),
+      "\x64".dup.force_encoding(Encoding::UTF_16)
+    ]
 
-      str.dup.taint.send(@method) do |x|
-        x.should.tainted?
-      end
-    end
+    "abcd".dup.force_encoding(Encoding::UTF_32).send(@method).to_a.should == [
+      "\x61".dup.force_encoding(Encoding::UTF_32),
+      "\x62".dup.force_encoding(Encoding::UTF_32),
+      "\x63".dup.force_encoding(Encoding::UTF_32),
+      "\x64".dup.force_encoding(Encoding::UTF_32)
+    ]
   end
 end