1 files changed, 33 insertions, 11 deletions
diff --git a/spec/ruby/library/stringio/readpartial_spec.rb b/spec/ruby/library/stringio/readpartial_spec.rb
index 2601fe8c42..dadefb7837 100644
--- a/spec/ruby/library/stringio/readpartial_spec.rb
+++ b/spec/ruby/library/stringio/readpartial_spec.rb
@@ -3,20 +3,14 @@ require_relative 'fixtures/classes'
 
 describe "StringIO#readpartial" do
   before :each do
-    @string = StringIO.new('Stop, look, listen')
+    @string = StringIO.new(+'Stop, look, listen')
   end
 
   after :each do
     @string.close unless @string.closed?
   end
 
-  it "raises IOError on closed stream" do
-    @string.close
-    -> { @string.readpartial(10) }.should raise_error(IOError)
-  end
-
   it "reads at most the specified number of bytes" do
-
     # buffered read
     @string.read(1).should == 'S'
     # return only specified number, not the whole buffer
@@ -30,6 +24,14 @@ describe "StringIO#readpartial" do
     @string.readpartial(3).should == ", l"
   end
 
+  it "reads after ungetc with multibyte characters in the buffer" do
+    @string = StringIO.new(+"∂φ/∂x = gaîté")
+    c = @string.getc
+    @string.ungetc(c)
+    @string.readpartial(3).should == "\xE2\x88\x82".b
+    @string.readpartial(3).should == "\xCF\x86/".b
+  end
+
   it "reads after ungetc without data in the buffer" do
     @string = StringIO.new
     @string.write("f").should == 1
@@ -48,7 +50,7 @@ describe "StringIO#readpartial" do
   end
 
   it "discards the existing buffer content upon successful read" do
-    buffer = "existing"
+    buffer = +"existing"
     @string.readpartial(11, buffer)
     buffer.should == "Stop, look,"
   end
@@ -59,7 +61,7 @@ describe "StringIO#readpartial" do
   end
 
   it "discards the existing buffer content upon error" do
-    buffer = 'hello'
+    buffer = +'hello'
     @string.readpartial(100)
     -> { @string.readpartial(1, buffer) }.should raise_error(EOFError)
     buffer.should be_empty
@@ -67,14 +69,34 @@ describe "StringIO#readpartial" do
 
   it "raises IOError if the stream is closed" do
     @string.close
-    -> { @string.readpartial(1) }.should raise_error(IOError)
+    -> { @string.readpartial(1) }.should raise_error(IOError, "not opened for reading")
   end
 
   it "raises ArgumentError if the negative argument is provided" do
-    -> { @string.readpartial(-1) }.should raise_error(ArgumentError)
+    -> { @string.readpartial(-1) }.should raise_error(ArgumentError, "negative length -1 given")
   end
 
   it "immediately returns an empty string if the length argument is 0" do
     @string.readpartial(0).should == ""
   end
+
+  it "raises IOError if the stream is closed and the length argument is 0" do
+    @string.close
+    -> { @string.readpartial(0) }.should raise_error(IOError, "not opened for reading")
+  end
+
+  it "clears and returns the given buffer if the length argument is 0" do
+    buffer = +"existing content"
+    @string.readpartial(0, buffer).should == buffer
+    buffer.should == ""
+  end
+
+  version_is StringIO::VERSION, "3.1.2" do # ruby_version_is "3.4"
+    it "preserves the encoding of the given buffer" do
+      buffer = ''.encode(Encoding::ISO_8859_1)
+      @string.readpartial(10, buffer)
+
+      buffer.encoding.should == Encoding::ISO_8859_1
+    end
+  end
 end