static string ref_string_read = "hello_dotnet_world_����.";     // The last 4 character are German umlauts.

static internal long Sread(IntPtr handle, System.IntPtr buffer, long buffersize)
{
    string s = ref_string_read + "\n";
    byte[] array = System.Text.Encoding.Unicode.GetBytes(s);
    System.Runtime.InteropServices.Marshal.Copy(array, 0, buffer, array.Length);
    return array.Length;
}


[TestMethod]
public void StreamRead()
{
    DelegateStreamReadFunction rf = new DelegateStreamReadFunction(Sread);
    PlEngine.SetStreamFunctionRead(PlStreamType.Input, rf);
    // NOTE: read/1 needs a dot ('.') at the end
    PlQuery.PlCall("assert( (test_read(A) :- read(A)) )");
    PlTerm t = PlQuery.PlCallQuery("test_read(A)");
    Assert.AreEqual(ref_string_read, t.ToString()+".");
}