@@ -2,6 +2,7 @@ package stdcopy

 import (

 	"bytes"

+	"errors"

 	"io/ioutil"

 	"strings"

 	"testing"

@@ -49,6 +50,41 @@ func TestWrite(t *testing.T) {

 	}

 }

+type errWriter struct {

+	n   int

+	err error

+}

+

+func (f *errWriter) Write(buf []byte) (int, error) {

+	return f.n, f.err

+}

+

+func TestWriteWithWriterError(t *testing.T) {

+	expectedError := errors.New("expected")

+	expectedReturnedBytes := 10

+	writer := NewStdWriter(&errWriter{

+		n:   stdWriterPrefixLen + expectedReturnedBytes,

+		err: expectedError}, Stdout)

+	data := []byte("This won't get written, sigh")

+	n, err := writer.Write(data)

+	if err != expectedError {

+		t.Fatalf("Didn't get expected error.")

+	}

+	if n != expectedReturnedBytes {

+		t.Fatalf("Didn't get expected writen bytes %d, got %d.",

+			expectedReturnedBytes, n)

+	}

+}

+

+func TestWriteDoesNotReturnNegativeWrittenBytes(t *testing.T) {

+	writer := NewStdWriter(&errWriter{n: -1}, Stdout)

+	data := []byte("This won't get written, sigh")

+	actual, _ := writer.Write(data)

+	if actual != 0 {

+		t.Fatalf("Expected returned written bytes equal to 0, got %d", actual)

+	}

+}

+

 func TestStdCopyWithInvalidInputHeader(t *testing.T) {

 	dstOut := NewStdWriter(ioutil.Discard, Stdout)

 	dstErr := NewStdWriter(ioutil.Discard, Stderr)