Verify something for each item in a list

[Flatscha]

I am trying to write an extension method for Mock to verify a call to every item in a list.

My extension:
public static void VerifyMultiple<T, TItem>(this Mock<T> value, Action<T, TItem> action, Times times, IEnumerable<TItem> items) where T : class { foreach (var item in items) { value.Verify(x => action(x, item), times); } }

Example call:
this._mockDAL.VerifyMultiple((x,i) => x.Save(i), Times.Once(), items);

But I get the error System.NotSupportedException: 'Unsupported expression: x'

I unfortunately do not know what is wrong with that call or why this exception is thrown
Can somebody explain?

[kzu]

Make your action parameter an Expression<Action<T, TItem>> instead? That's the type Mock<T>.Verify receives and is that makes it possible to inspect which mock member invocation to verify.

[Flatscha]

Unfortunately I already tried that and it doesn't change anything.