1 files changed, 14 insertions, 12 deletions
diff --git a/spec/ruby/core/string/encode_spec.rb b/spec/ruby/core/string/encode_spec.rb
index 5604ab7210..97dd753b62 100644
--- a/spec/ruby/core/string/encode_spec.rb
+++ b/spec/ruby/core/string/encode_spec.rb
@@ -34,8 +34,8 @@ describe "String#encode" do
 
     it "encodes an ascii substring of a binary string to UTF-8" do
       x82 = [0x82].pack('C')
-      str =  "#{x82}foo".force_encoding("binary")[1..-1].encode("utf-8")
-      str.should == "foo".force_encoding("utf-8")
+      str =  "#{x82}foo".dup.force_encoding("binary")[1..-1].encode("utf-8")
+      str.should == "foo".dup.force_encoding("utf-8")
       str.encoding.should equal(Encoding::UTF_8)
     end
   end
@@ -49,7 +49,7 @@ describe "String#encode" do
     end
 
     it "round trips a String" do
-      str = "abc def".force_encoding Encoding::US_ASCII
+      str = "abc def".dup.force_encoding Encoding::US_ASCII
       str.encode("utf-32be").encode("ascii").should == "abc def"
     end
   end
@@ -79,6 +79,10 @@ describe "String#encode" do
       encoded.encode("UTF-8").should == "ちfoofoo"
     end
 
+    it "replace multiple invalid bytes at the end with a single replacement character" do
+      "\xE3\x81\x93\xE3\x81".encode("UTF-8", invalid: :replace).should == "\u3053\ufffd"
+    end
+
     it "replaces invalid encoding in source using a specified replacement even when a fallback is given" do
       encoded = "ち\xE3\x81\xFF".encode("UTF-16LE", invalid: :replace, replace: "foo", fallback: -> c { "bar" })
       encoded.should == "\u3061foofoo".encode("UTF-16LE")
@@ -118,8 +122,7 @@ describe "String#encode" do
 
   describe "when passed to, from" do
     it "returns a copy in the destination encoding when both encodings are the same" do
-      str = "あ"
-      str.force_encoding("binary")
+      str = "あ".dup.force_encoding("binary")
       encoded = str.encode("utf-8", "utf-8")
 
       encoded.should_not equal(str)
@@ -151,8 +154,7 @@ describe "String#encode" do
     end
 
     it "returns a copy in the destination encoding when both encodings are the same" do
-      str = "あ"
-      str.force_encoding("binary")
+      str = "あ".dup.force_encoding("binary")
       encoded = str.encode("utf-8", "utf-8", invalid: :replace)
 
       encoded.should_not equal(str)
@@ -187,13 +189,13 @@ describe "String#encode!" do
   describe "when passed no options" do
     it "returns self when Encoding.default_internal is nil" do
       Encoding.default_internal = nil
-      str = "あ"
+      str = +"あ"
       str.encode!.should equal(str)
     end
 
     it "returns self for a ASCII-only String when Encoding.default_internal is nil" do
       Encoding.default_internal = nil
-      str = "abc"
+      str = +"abc"
       str.encode!.should equal(str)
     end
   end
@@ -201,14 +203,14 @@ describe "String#encode!" do
   describe "when passed options" do
     it "returns self for ASCII-only String when Encoding.default_internal is nil" do
       Encoding.default_internal = nil
-      str = "abc"
+      str = +"abc"
       str.encode!(invalid: :replace).should equal(str)
     end
   end
 
   describe "when passed to encoding" do
     it "returns self" do
-      str = "abc"
+      str = +"abc"
       result = str.encode!(Encoding::BINARY)
       result.encoding.should equal(Encoding::BINARY)
       result.should equal(str)
@@ -217,7 +219,7 @@ describe "String#encode!" do
 
   describe "when passed to, from" do
     it "returns self" do
-      str = "ああ"
+      str = +"ああ"
       result = str.encode!("euc-jp", "utf-8")
       result.encoding.should equal(Encoding::EUC_JP)
       result.should equal(str)