public void TestAddDirectoryFail()
{
_mockStore1.Setup(x => x.Contains(_digest1)).Returns(false);
_mockStore2.Setup(x => x.Contains(_digest1)).Returns(false);
_mockStore2.Setup(x => x.AddDirectory("path", _digest1, _handler)).Throws(new IOException("Fake IO exception for testing"));
_mockStore1.Setup(x => x.AddDirectory("path", _digest1, _handler)).Throws(new IOException("Fake IO exception for testing"));
_testStore.Invoking(x => x.AddDirectory("path", _digest1, _handler)).ShouldThrow <IOException>(because: "Should pass through fatal exceptions");
}