internal static void Verify(TestContext tc, string testname, TabWriter w, Buffer b, ustring src, ustring expected)
{
w.Flush();
var res = b.ToUstring();
// DBG:
tc.WriteLine($" expected = {expected.Slice()}");
tc.WriteLine($" found = {res.Slice()}");
Assert.AreEqual(expected, res,
$"--- test: {testname}\n--- src:\n{src}\n--- found:\n{res}\n--- expected:\n{expected}\n");
}
