public void Exporters_XrefExporter_getCustomValue()
        {
            string   key1  = "DOC000123";
            string   key2  = "DOC000124";
            string   field = "DocType";
            string   value = "Email";
            Document doc   = new Document(key1, null, null, new Dictionary <string, string>()
            {
                { field, value }
            }, null);
            TestExporter exporter = new TestExporter();

            Assert.AreEqual(value, exporter.getCustomValue(key1, doc, field));
            Assert.AreEqual(String.Empty, exporter.getCustomValue(key2, doc, field));
            Assert.AreEqual(String.Empty, exporter.getCustomValue(key1, doc, null));
            Assert.AreEqual(String.Empty, exporter.getCustomValue(key1, doc, String.Empty));
            Assert.AreEqual(String.Empty, exporter.getCustomValue(key1, doc, "bananas"));
        }