/// <summary>
/// Two changes have been made, first on firstStack, then on secondStack. Verify that they must be Undone
/// in the reverse order, and redone in the same order.
/// </summary>
/// <param name="firstStack"></param>
/// <param name="secondStack"></param>
private void VerifyOrderRequired(IActionHandler firstStack, IActionHandler secondStack)
{
Assert.That(firstStack.CanUndo(), Is.False); // can't undo the first change before the other.
Assert.That(secondStack.CanUndo(), Is.True);
secondStack.Undo(); // get back to where we can Undo creating it.
Assert.That(firstStack.CanUndo(), Is.True); // now the second one is undone, we can
firstStack.Undo(); // now both are undone.
Assert.That(secondStack.CanRedo(), Is.False); // can't redo the second change first
Assert.That(firstStack.CanRedo(), Is.True); // but of course we can redo the first one first
firstStack.Redo();
Assert.That(secondStack.CanRedo(), Is.True); // now we can redo the second change, since we already redid the first.
}
