public void Can_merge_intersecting_props()
        {
            var p1 = new AppProps();
            p1.Append("key1", "value1");
            var p2 = new AppProps();
            p2.Append("key1", "value2");

            var merged = AppProps.Merge(p1, p2);

            Assert.AreEqual("value2", merged["key1"]);

            AssertItemsCountInOutputFile(merged, 1);
        }