Unit test to verify the balance of BinaryReader/Writer for char arrays. Could be expanded to form a complete balance test for all calls.

gistfile1.cs

    [TestClass]
    public class BinaryReaderWriterBalance
    {

        class TestBinaryWriter : BinaryWriter
        {
            private int _counter;

            public TestBinaryWriter(Stream output)
                : base(output)
            {
            }

            public override void Write(char[] chars)
            {
                base.Write(_counter++);
                base.Write(chars);
            }

            public override void Write(char[] chars, int index, int count)
            {
                base.Write(_counter++);
                base.Write(chars, index, count);
            }
        }

        class TestBinaryReader : BinaryReader
        {
            private int _counter;

            public TestBinaryReader(Stream input)
                : base(input)
            {
            }

            public override char[] ReadChars(int count)
            {
                Assert.AreEqual(_counter++, base.ReadInt32());
                return base.ReadChars(count);
            }

            public override int Read(char[] buffer, int index, int count)
            {
                Assert.AreEqual(_counter++, base.ReadInt32());
                return base.Read(buffer, index, count);
            }
        }


        [TestMethod]
        public void TestCharReadWriteBalance()
        {
            var stream = new MemoryStream();

            var writeChars = "TEST".ToCharArray();

            var writer = new TestBinaryWriter(stream);
            writer.Write(writeChars);
            writer.Write(writeChars, 0, writeChars.Length);

            stream.Seek(0, SeekOrigin.Begin);

            var reader = new TestBinaryReader(stream);
            var readChars = reader.ReadChars(writeChars.Length);
            reader.Read(readChars, 0, writeChars.Length);
        }
    }