How can I build an IOptionsMonitor<T> for testing?

Question

For the normal IOptions interface, you can manually build an instance e.g. this SO question.

Is there any equivalent way to make an IOptionsMonitor instance without using DI?

Answer 1

nice answer from Hananiel

Here the generic version of it:

public class TestOptionsMonitor<T> : IOptionsMonitor<T>
    where T : class, new()
{
    public TestOptionsMonitor(T currentValue)
    {
        CurrentValue = currentValue;
    }

    public T Get(string name)
    {
        return CurrentValue;
    }

    public IDisposable OnChange(Action<T, string> listener)
    {
        throw new NotImplementedException();
    }

    public T CurrentValue { get; }
}

and simply create an instance with your object!

Answer 2

You can do something like below and and then use that for testing:

    public class TestOptionsMonitor : IOptionsMonitor<MyOptions>
    {
        public TestOptionsMonitor(MyOptions currentValue)
        {
            CurrentValue = currentValue;
        }

        public MyOptions Get(string name)
        {
            return CurrentValue;
        }

        public IDisposable OnChange(Action<MyOptions, string> listener)
        {
            throw new NotImplementedException();
        }

        public MyOptions CurrentValue { get; }
    }