public void Preload_test() { // arrange var field1 = "test"; var field2 = DateTime.UtcNow; storage[0] = new Dictionary<string, object>{ {"Field1", field1}, {"Field2", field2} }; var foo = new Foo(0, dBCollectionMock.Object); // act foo.Preload(x => x.Field1); var val1 = foo.Field1; var val2 = foo.Field2; // assert val1.Should().Be(field1); val2.Should().Be(field2); dBCollectionMock.Verify(x => x.GetModelField(0, It.IsAny<string>()), Times.Once); }