OverviewVM null repository test

OverviewVMTests.cs

    [Test]
    public void creating_a_new_instance_of_OverviewVM_with_null_repository_throws_ArgumentNullException()
    {
        // Assert
        Assert.That(() => new OverviewVM(null),
            Throws.Exception
                .TypeOf<ArgumentNullException>()
                .With.Property("ParamName")
                .EqualTo("toDoRepo"));
    }