public void TestContext()
{
SeekableStringReader s = new SeekableStringReader("abcdefghijklmnopqrstuvwxyz");
s.Read(10);
string left, right;
s.Context(-1, 5, out left, out right);
Assert.AreEqual("fghij", left);
Assert.AreEqual("klmno", right);
s.Context(-1, 12, out left, out right);
Assert.AreEqual("abcdefghij", left);
Assert.AreEqual("klmnopqrstuv", right);
s.Read(13);
s.Context(-1, 6, out left, out right);
Assert.AreEqual("rstuvw", left);
Assert.AreEqual("xyz", right);
s.Context(5, 4, out left, out right);
Assert.AreEqual("bcde", left);
Assert.AreEqual("fghi", right);
}