public void ShouldThrowExceptionWhenGetCacheKeysFails()
{
_cacheDataSource = new Mock<ICacheDataSource<DummyModel>>();
_cacheDataSource.Setup(a => a.GetKeys()).Throws(new Exception());
var cache = new Cache<DummyModel>(_cacheDataSource.Object);
Assert.Throws<BlogException>(() => cache.GetKeys());
}