public void ExstsReturnsListOfPersons()
{
//Assert
moq.Setup(m => m.Exists(It.IsAny <Person>())).Returns <Person>(p => Task.FromResult(new List <Person> {
p
} as IEnumerable <Person>));
long personId = 3;
//Act
var result = controller.Exists(new Person {
Id = personId
}).Result;
//Assert
Assert.IsInstanceOfType(result, typeof(IEnumerable <Person>));
Assert.AreEqual(personId, (result as List <Person>)?[0]?.Id);
}