Musify/backend/Tests/Musify.Application.Tests/YouTube/SearchYouTubeTracksQueryHandlerTests.cs

using ErrorOr;
using Musify.Application.Contracts;
using Musify.Application.YouTube;
using NSubstitute;
using Xunit;

namespace Musify.Application.Tests.YouTube
{
    public sealed class SearchYouTubeTracksQueryHandlerTests
    {
        private readonly IYouTubeMusicService youTubeMusicService = Substitute.For<IYouTubeMusicService>();

        private SearchYouTubeTracksQueryHandler CreateHandler() => new(youTubeMusicService);

        [Fact]
        public async Task Handle_EmptyQuery_ReturnsValidationErrorWithoutCallingTheService()
        {
            var result = await CreateHandler().Handle(new SearchYouTubeTracksQuery(string.Empty, string.Empty), TestContext.Current.CancellationToken);

            Assert.Equal(ErrorType.Validation, result.FirstError.Type);
            await youTubeMusicService.DidNotReceiveWithAnyArgs()
                .SearchSongsAsync(default!, default!, TestContext.Current.CancellationToken);
        }

        [Fact]
        public async Task Handle_NonEmptyQuery_DelegatesToTheService()
        {
            var expected = new YouTubeSearchResult([], "next-token");
            youTubeMusicService.SearchSongsAsync("query", "token", Arg.Any<CancellationToken>()).Returns(expected);

            var result = await CreateHandler().Handle(new SearchYouTubeTracksQuery("query", "token"), TestContext.Current.CancellationToken);

            Assert.False(result.IsError);
            Assert.Same(expected, result.Value);
        }
    }
}