1 files changed, 102 insertions, 0 deletions
diff --git a/spec/ruby/library/stringio/readpartial_spec.rb b/spec/ruby/library/stringio/readpartial_spec.rb
new file mode 100644
index 0000000000..dadefb7837
--- /dev/null
+++ b/spec/ruby/library/stringio/readpartial_spec.rb
@@ -0,0 +1,102 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "StringIO#readpartial" do
+  before :each do
+    @string = StringIO.new(+'Stop, look, listen')
+  end
+
+  after :each do
+    @string.close unless @string.closed?
+  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
+    @string.readpartial(1).should == "t"
+  end
+
+  it "reads after ungetc with data in the buffer" do
+    c = @string.getc
+    @string.ungetc(c)
+    @string.readpartial(4).should == "Stop"
+    @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
+    @string.rewind
+    c = @string.getc
+    c.should == 'f'
+    @string.ungetc(c).should == nil
+
+    @string.readpartial(2).should == "f"
+    @string.rewind
+    # now, also check that the ungot char is cleared and
+    # not returned again
+    @string.write("b").should == 1
+    @string.rewind
+    @string.readpartial(2).should == "b"
+  end
+
+  it "discards the existing buffer content upon successful read" do
+    buffer = +"existing"
+    @string.readpartial(11, buffer)
+    buffer.should == "Stop, look,"
+  end
+
+  it "raises EOFError on EOF" do
+    @string.readpartial(18).should == 'Stop, look, listen'
+    -> { @string.readpartial(10) }.should raise_error(EOFError)
+  end
+
+  it "discards the existing buffer content upon error" do
+    buffer = +'hello'
+    @string.readpartial(100)
+    -> { @string.readpartial(1, buffer) }.should raise_error(EOFError)
+    buffer.should be_empty
+  end
+
+  it "raises IOError if the stream is closed" do
+    @string.close
+    -> { @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, "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