public void Exporters_XrefExporter_getNextImageKey()
{
var docs = GetDocs();
TestExporter exporter = new TestExporter();
exporter.SetDocs(docs);
Assert.AreEqual("DOC000002", exporter.getNextImageKey(0, 0));
Assert.AreEqual("DOC000003", exporter.getNextImageKey(0, 1));
Assert.AreEqual(null, exporter.getNextImageKey(1, 1));
Assert.AreEqual(null, exporter.getNextImageKey(2, 1));
}