gistfile1.cs

[TestMethod]
public async Task TestLocationSearchHasResult()
{
  var testVm = new GeocodeViewModel { SearchText = "Springerstraat Amersfoort Netherlands" };
  await Deployment.Current.Dispatcher.InvokeTaskAsync(() => testVm.SearchLocation());
  Assert.IsTrue(testVm.MapLocations.Any());
}

public static class DispatcherExtensions
{
    public static Task<T> InvokeTaskAsync<T>(this Dispatcher dispatcher, Func<Task<T>> func)
    {
        var tcs = new TaskCompletionSource<T>();
        dispatcher.BeginInvoke(new Action(async () =>{
            try
            {
                var result = await func();
                tcs.SetResult(result);
            }
            catch (Exception e)
            {
                tcs.SetException(e);
            }
        }));
        
        return tcs.Task;
    }
    
    public static Task<T> InvokeAsync<T>(this Dispatcher dispatcher, Func<T> func)
    {
        var tcs = new TaskCompletionSource<T>();
        dispatcher.BeginInvoke(new Action(()=>{
            try
            {
                var result = func();
                tcs.SetResult(result);
            }
            catch (Exception e)
            {
                tcs.SetException(e);
            }
        }));
        
        return tcs.Task;
    }
}