Moq callback method not hit within lambda expression

Question

I have an issue while trying to get parameter values from MOQ Method using Callback.

// Test 1 - can get parameters in moq method callback - OK
var test = _myService.GetValues(9, 9).ToList();

// Test 2 - can not drill into moq method callback - KO
var test2 = mylist
.Select(x => _myService.GetValues(x.p1, x.p2).ToList());

// with:
var l1 = new list<int>();
var _myService = new Mock<MyService>();

_myService
    .Setup(x => x.GetValues(It.IsAny<int>(), It.IsAny<int>()))
    .Returns(something)
    .Callback<int, int>((a, b) => l1.Add(a));

Can someone explain me why ?

Provide a minimal reproducible example that reproduces the problem other wise the question will remain unclear and will be closed. — Nkosi
– Nkosi, Commented Nov 15, 2016 at 17:26

Nkosi · Accepted Answer · 2016-11-15 17:45:09Z

3

Unless the Select query is enumerated the lambda expression is not executed. That is why it appears not to work.

Enumerate the select and everything should work as expected.

var test2 = mylist
.Select(x => _myService.GetValues(x.p1, x.p2).ToList())
.ToList();

OR

var test2 = mylist
.Select(x => _myService.GetValues(x.p1, x.p2).ToList());
foreach(var x in test2) { ... }

edited Nov 15, 2016 at 17:45

answered Nov 15, 2016 at 17:35

Nkosi

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