1 files changed, 23 insertions, 18 deletions
diff --git a/spec/ruby/core/io/sysread_spec.rb b/spec/ruby/core/io/sysread_spec.rb
index e7f63cefec..2d58db2250 100644
--- a/spec/ruby/core/io/sysread_spec.rb
+++ b/spec/ruby/core/io/sysread_spec.rb
@@ -21,25 +21,25 @@ describe "IO#sysread on a file" do
   end
 
   it "reads the specified number of bytes from the file to the buffer" do
-    buf = "" # empty buffer
+    buf = +"" # empty buffer
     @file.sysread(15, buf).should == buf
     buf.should == "012345678901234"
 
     @file.rewind
 
-    buf = "ABCDE" # small buffer
+    buf = +"ABCDE" # small buffer
     @file.sysread(15, buf).should == buf
     buf.should == "012345678901234"
 
     @file.rewind
 
-    buf = "ABCDE" * 5 # large buffer
+    buf = +"ABCDE" * 5 # large buffer
     @file.sysread(15, buf).should == buf
     buf.should == "012345678901234"
   end
 
   it "coerces the second argument to string and uses it as a buffer" do
-    buf = "ABCDE"
+    buf = +"ABCDE"
     (obj = mock("buff")).should_receive(:to_str).any_number_of_times.and_return(buf)
     @file.sysread(15, obj).should == buf
     buf.should == "012345678901234"
@@ -52,7 +52,7 @@ describe "IO#sysread on a file" do
 
   it "raises an error when called after buffered reads" do
     @file.readline
-    -> { @file.sysread(5) }.should raise_error(IOError)
+    -> { @file.sysread(5) }.should.raise(IOError)
   end
 
   it "reads normally even when called immediately after a buffered IO#read" do
@@ -63,13 +63,13 @@ describe "IO#sysread on a file" do
   it "does not raise error if called after IO#read followed by IO#write" do
     @file.read(5)
     @file.write("abcde")
-    -> { @file.sysread(5) }.should_not raise_error(IOError)
+    -> { @file.sysread(5) }.should_not.raise(IOError)
   end
 
   it "does not raise error if called after IO#read followed by IO#syswrite" do
     @file.read(5)
     @file.syswrite("abcde")
-    -> { @file.sysread(5) }.should_not raise_error(IOError)
+    -> { @file.sysread(5) }.should_not.raise(IOError)
   end
 
   it "reads updated content after the flushed buffered IO#write" do
@@ -82,7 +82,7 @@ describe "IO#sysread on a file" do
   end
 
   it "raises IOError on closed stream" do
-    -> { IOSpecs.closed_io.sysread(5) }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.sysread(5) }.should.raise(IOError)
   end
 
   it "immediately returns an empty string if the length argument is 0" do
@@ -90,22 +90,29 @@ describe "IO#sysread on a file" do
   end
 
   it "immediately returns the given buffer if the length argument is 0" do
-    buffer = "existing content"
+    buffer = +"existing content"
     @file.sysread(0, buffer).should == buffer
     buffer.should == "existing content"
   end
 
   it "discards the existing buffer content upon successful read" do
-    buffer = "existing content"
-    @file.sysread(11, buffer)
+    buffer = +"existing content"
+    @file.sysread(11, buffer).should.equal?(buffer)
     buffer.should == "01234567890"
   end
 
   it "discards the existing buffer content upon error" do
-    buffer = "existing content"
+    buffer = +"existing content"
     @file.seek(0, :END)
-    -> { @file.sysread(1, buffer) }.should raise_error(EOFError)
-    buffer.should be_empty
+    -> { @file.sysread(1, buffer) }.should.raise(EOFError)
+    buffer.should.empty?
+  end
+
+  it "preserves the encoding of the given buffer" do
+    buffer = ''.encode(Encoding::ISO_8859_1)
+    string = @file.sysread(10, buffer)
+
+    buffer.encoding.should == Encoding::ISO_8859_1
   end
 end
 
@@ -124,9 +131,7 @@ describe "IO#sysread" do
     @read.sysread(3).should == "ab"
   end
 
-  guard_not -> { platform_is :windows and ruby_version_is ""..."3.2" } do # https://bugs.ruby-lang.org/issues/18880
-    it "raises ArgumentError when length is less than 0" do
-      -> { @read.sysread(-1) }.should raise_error(ArgumentError)
-    end
+  it "raises ArgumentError when length is less than 0" do
+    -> { @read.sysread(-1) }.should.raise(ArgumentError)
   end
 end