Musify/backend/Tests/Musify.Application.Tests/TestSupport/HandlerTestBase.cs

using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Logging.Abstractions;
using Xunit;

namespace Musify.Application.Tests.TestSupport
{
    /// <summary>
    /// Base class for handler tests: gives every test method its own empty, isolated
    /// <see cref="TestDatabase"/> (xUnit creates a new instance of the test class per test method,
    /// so there is no state to reset between tests) and a no-op logger factory for handlers that
    /// take an <see cref="ILogger{TCategoryName}"/>.
    /// </summary>
    public abstract class HandlerTestBase : IAsyncLifetime
    {
        private TestDatabase database = null!;

        protected TestDatabase Database => database;

        public async ValueTask InitializeAsync() => database = await TestDatabase.CreateAsync();

        public ValueTask DisposeAsync() => database.DisposeAsync();

        protected static ILogger<T> NoOpLogger<T>() => NullLogger<T>.Instance;

        /// <summary>Adds the entities and persists them, so handlers under test see committed data.</summary>
        protected async Task SeedAsync(params object[] entities)
        {
            foreach (var entity in entities)
                Database.Add(entity);

            await Database.SaveChangesAsync(CancellationToken.None);
        }
    }
}