static void Check(TextBoxEditor editor, string keys, TextSlice expected)
        {
            var clipboardProvider = new TestClipboardProvider();

            editor.Interpret(keys);
            Assert.AreEqual(expected, editor.TextSlice, "Expected result of keystroke");
        }
        public void ClipboardAccess()
        {
            IClipboardProvider clipboardProvider = new TestClipboardProvider();
            var editor = new TextBoxEditor(clipboardProvider);

            Assert.IsNull(clipboardProvider.GetText());
            editor.Interpret("Hello World");
            editor.SelectAll();
            editor.Interpret("^C");
            Assert.AreEqual("Hello World", clipboardProvider.GetText());
            editor.Interpret("^V");
            editor.Interpret("^V");
            Assert.AreEqual("Hello WorldHello World", editor.TextSlice.Text);
        }