Fix test bad practices and tighten weak assertions

- StorageServiceTests: replace out-param + manual dispose with IAsyncLifetime
- PictureServiceTests: Assert.True bound checks -> Assert.InRange
- CreateAlbumCommandHandlerTests: assert the specific NotFound error type
  instead of just IsError, matching what the test name promises
- CreateAlbumRequestValidatorTests: replace a boundary Theory that computed
  its expected result inline with explicit Facts against the real
  AlbumReleaseYear constants
- Remove unused using directives across a handful of production and test
  files found during the review

Full suite verified green: 250/250 tests passing, 0 build warnings.

backend/Core/Musify.Application/ApplicationDependencyInjection.cs

@@ -1,4 +1,3 @@
-using Mediator;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 using Musify.Application.Configuration;

backend/Core/Musify.Application/Tracks/Responses/TrackApplicationResponse.cs

@@ -1,4 +1,3 @@
-using System.Linq;
 using Musify.Domain.Entities;
 using Musify.Domain.ValueObjects;
 

backend/Core/Musify.Infrastructure/MassTransit/RoutingSlip/Builders/AudioWorkflowRoutingSlipBuilder.cs

@@ -4,7 +4,6 @@ using Musify.Application.Events;
 using Musify.Infrastructure.Configuration;
 using Musify.Infrastructure.MassTransit.Activities.Audio;
 using Musify.Infrastructure.MassTransit.Activities.Files;
-using Musify.Infrastructure.MassTransit.Activities;
 using Musify.Infrastructure.MassTransit.Arguments;
 using Musify.Infrastructure.MassTransit.Consumers;
 

backend/Core/Musify.Infrastructure/Persistence/DatabaseDependencyInjection.cs

@@ -1,4 +1,3 @@
-using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Options;

backend/Core/Musify.Infrastructure/Persistence/Migrations/20260705123932_AddTrackProcessingStateSaga.cs

@@ -1,5 +1,4 @@
-using System;
+using Microsoft.EntityFrameworkCore.Migrations;
-using Microsoft.EntityFrameworkCore.Migrations;
 
 #nullable disable
 

backend/Core/Musify.Infrastructure/Persistence/Migrations/20260705125356_AddPlayListProcessingStateSaga.cs

@@ -1,5 +1,4 @@
-using System;
+using Microsoft.EntityFrameworkCore.Migrations;
-using Microsoft.EntityFrameworkCore.Migrations;
 
 #nullable disable
 

backend/Core/Musify.Infrastructure/Persistence/Migrations/20260713234847_AddListeningHistory.cs

@@ -1,5 +1,4 @@
-using System;
+using Microsoft.EntityFrameworkCore.Migrations;
-using Microsoft.EntityFrameworkCore.Migrations;
 
 #nullable disable
 

backend/Core/Musify.Infrastructure/Persistence/Migrations/20260716214752_AddArtistsAndTrackOwnership.cs

@@ -1,4 +1,3 @@
-using System;
 using Microsoft.EntityFrameworkCore.Migrations;
 
 #nullable disable

backend/Core/Musify.Infrastructure/Persistence/Migrations/20260717172507_SplitTrackIntoLocalAndExternal.cs

@@ -1,4 +1,3 @@
-using System;
 using Microsoft.EntityFrameworkCore.Migrations;
 
 #nullable disable

backend/Core/Musify.Infrastructure/Persistence/Migrations/20260720180747_AddAlbums.cs

@@ -1,5 +1,4 @@
-using System;
+using Microsoft.EntityFrameworkCore.Migrations;
-using Microsoft.EntityFrameworkCore.Migrations;
 
 #nullable disable
 

backend/Core/Musify.Infrastructure/Persistence/Migrations/20260721155102_AddMixes.cs

@@ -1,5 +1,4 @@
-using System;
+using Microsoft.EntityFrameworkCore.Migrations;
-using Microsoft.EntityFrameworkCore.Migrations;
 
 #nullable disable
 

backend/Core/Musify.Infrastructure/Persistence/Migrations/20260721162102_DropMixGeneratedOn.cs

@@ -1,5 +1,4 @@
-using System;
+using Microsoft.EntityFrameworkCore.Migrations;
-using Microsoft.EntityFrameworkCore.Migrations;
 
 #nullable disable
 

backend/Core/Musify.Infrastructure/Persistence/Migrations/20260724181012_AddExternalAlbums.cs

@@ -1,5 +1,4 @@
-using System;
+using Microsoft.EntityFrameworkCore.Migrations;
-using Microsoft.EntityFrameworkCore.Migrations;
 
 #nullable disable
 

backend/Hosts/Musify.Api/OpenApi/OpenApiExtensions.cs

@@ -1,5 +1,3 @@
-using Microsoft.AspNetCore.OpenApi;
-
 namespace Musify.Api.OpenApi;
 
 public static class OpenApiExtensions

backend/Hosts/Musify.Worker/Program.cs

@@ -1,6 +1,4 @@
 using Hangfire;
-using Mediator;
-using Microsoft.Extensions.DependencyInjection;
 using Musify.Application.Configuration;
 using Musify.Application.Services;
 using Musify.Infrastructure.Jobs;

backend/Tests/Musify.Api.Tests/Validators/CreateAlbumRequestValidatorTests.cs

@@ -41,20 +41,34 @@ public sealed class CreateAlbumRequestValidatorTests
         Assert.False(result.IsValid);
     }
 
-    [Theory]
+    [Fact]
-    [InlineData(1876)]
+    public void Validate_ReleaseYearBeforeTheEarliestBoundary_Fails()
-    [InlineData(1877)]
-    public void Validate_ReleaseYearAtOrBeforeTheEarliestBoundary(int year)
     {
-        var result = validator.Validate(new CreateAlbumRequest("Title", null, year));
+        var result = validator.Validate(new CreateAlbumRequest("Title", null, AlbumReleaseYear.Earliest - 1));
 
-        Assert.Equal(year >= 1877, result.IsValid);
+        Assert.False(result.IsValid);
     }
 
     [Fact]
-    public void Validate_ReleaseYearMoreThanOneYearInTheFuture_Fails()
+    public void Validate_ReleaseYearAtTheEarliestBoundary_Passes()
     {
-        var result = validator.Validate(new CreateAlbumRequest("Title", null, DateTime.UtcNow.Year + 2));
+        var result = validator.Validate(new CreateAlbumRequest("Title", null, AlbumReleaseYear.Earliest));
+
+        Assert.True(result.IsValid);
+    }
+
+    [Fact]
+    public void Validate_ReleaseYearAtTheLatestBoundary_Passes()
+    {
+        var result = validator.Validate(new CreateAlbumRequest("Title", null, AlbumReleaseYear.Latest));
+
+        Assert.True(result.IsValid);
+    }
+
+    [Fact]
+    public void Validate_ReleaseYearPastTheLatestBoundary_Fails()
+    {
+        var result = validator.Validate(new CreateAlbumRequest("Title", null, AlbumReleaseYear.Latest + 1));
 
         Assert.False(result.IsValid);
     }

backend/Tests/Musify.Application.Tests/Albums/CreateAlbumCommandHandlerTests.cs

@@ -1,3 +1,4 @@
+using ErrorOr;
 using Musify.Application.Albums;
 using Musify.Application.Tests.TestSupport;
 using Xunit;
@@ -37,7 +38,6 @@ public sealed class CreateAlbumCommandHandlerTests : HandlerTestBase
 
         var result = await CreateHandler().Handle(command, CancellationToken.None);
 
-        Assert.True(result.IsError);
+        Assert.Equal(ErrorType.NotFound, result.FirstError.Type);
-        Assert.Equal(ErrorOr.ErrorType.NotFound, result.FirstError.Type);
     }
 }

backend/Tests/Musify.Application.Tests/Mixes/GenerateMixesForUserCommandHandlerTests.cs

@@ -3,7 +3,6 @@ using Musify.Application.Contracts;
 using Musify.Application.Mixes;
 using Musify.Application.Tests.TestSupport;
 using Musify.Domain.Entities;
-using Musify.Domain.ValueObjects;
 using NSubstitute;
 using Xunit;
 
@@ -47,7 +46,7 @@ public sealed class GenerateMixesForUserCommandHandlerTests : HandlerTestBase
         youTubeMusicService
             .SearchSongsAsync(Arg.Any<string>(), Arg.Any<string>(), Arg.Any<CancellationToken>())
             .Returns(new YouTubeSearchResult(
-                [new YouTubeSongResult("yt-1", "YouTube Song", "Seed Artist", "Album", 200, "https://img/thumb.jpg", false, [])],
+                [new YouTubeSongResult("yt-1", "YouTube Song", "Seed Artist", "Album", 200, "https://img/thumb.jpg", IsExplicit: false, [] )],
                 ContinuationToken: string.Empty));
         youTubeMusicService.ResolveArtworkUrl(Arg.Any<string>()).Returns(callInfo => callInfo.Arg<string>());
 

backend/Tests/Musify.Application.Tests/PlayLists/AddYouTubeTrackToPlayListCommandHandlerTests.cs

@@ -5,7 +5,6 @@ using Musify.Application.PlayLists;
 using Musify.Application.Services;
 using Musify.Application.Tests.TestSupport;
 using Musify.Domain.Entities;
-using Musify.Domain.ValueObjects;
 using NSubstitute;
 using Xunit;
 

backend/Tests/Musify.Application.Tests/PlayLists/CreatePlayListCommandHandlerTests.cs

@@ -1,5 +1,4 @@
 using ErrorOr;
-using Musify.Application.Configuration;
 using Musify.Application.Contracts;
 using Musify.Application.PlayLists;
 using Musify.Application.Services;

backend/Tests/Musify.Application.Tests/Tracks/GetTrackCoverQueryHandlerTests.cs

@@ -1,7 +1,6 @@
 using ErrorOr;
 using Musify.Application.Tests.TestSupport;
 using Musify.Application.Tracks;
-using Musify.Domain.ValueObjects;
 using Xunit;
 
 namespace Musify.Application.Tests.Tracks;

backend/Tests/Musify.Infrastructure.Tests/Persistence/AuditableEntityInterceptorTests.cs

@@ -1,4 +1,3 @@
-using Microsoft.EntityFrameworkCore;
 using Musify.Domain.Entities;
 using Musify.Infrastructure.Tests.TestSupport;
 using Xunit;

backend/Tests/Musify.Infrastructure.Tests/Services/PictureServiceTests.cs

@@ -27,9 +27,9 @@ public sealed class PictureServiceTests
         await using var resized = await CreateService().ResizePictureAsWebpAsync(source, 200, 200, CancellationToken.None);
 
         using var result = await Image.LoadAsync(resized);
-        Assert.True(result.Width <= 200);
+        Assert.InRange(result.Width, 1, 200);
-        Assert.True(result.Height <= 200);
+        Assert.InRange(result.Height, 1, 200);
-        Assert.True(result.Width == 200 || result.Height == 200);
+        Assert.True(result.Width == 200 || result.Height == 200, "expected the longer side to land exactly on the target box");
     }
 
     [Fact]

backend/Tests/Musify.Infrastructure.Tests/Services/StorageServiceTests.cs

@@ -1,7 +1,9 @@
 using System.Net;
+using System.Net.Http.Headers;
 using System.Text;
 using Microsoft.Extensions.Logging.Abstractions;
 using Musify.Infrastructure.Configuration;
+using Musify.Infrastructure.Persistence;
 using Musify.Infrastructure.Services;
 using Musify.Infrastructure.Tests.TestSupport;
 using Xunit;
@@ -9,9 +11,12 @@ using Xunit;
 namespace Musify.Infrastructure.Tests.Services;
 
 [Collection(InfrastructureCollection.Name)]
-public sealed class StorageServiceTests(InfrastructureTestFixture fixture)
+public sealed class StorageServiceTests(InfrastructureTestFixture fixture) : IAsyncLifetime
 {
-    private StorageService CreateService(out Musify.Infrastructure.Persistence.Database database)
+    private Database database = null!;
+    private StorageService service = null!;
+
+    public Task InitializeAsync()
     {
         database = fixture.CreateDatabase();
         var storageConfiguration = new InfrastructureStorageConfiguration
@@ -22,14 +27,15 @@ public sealed class StorageServiceTests(InfrastructureTestFixture fixture)
             ForcePathStyle = true,
             UseHttp = true,
         };
-        return new StorageService(database, fixture.CreateS3Client(), NullLogger<StorageService>.Instance, storageConfiguration);
+        service = new StorageService(database, fixture.CreateS3Client(), NullLogger<StorageService>.Instance, storageConfiguration);
+        return Task.CompletedTask;
     }
 
+    public Task DisposeAsync() => database.DisposeAsync().AsTask();
+
     [Fact]
     public async Task UploadThenGetFile_RoundTripsTheSameBytes()
     {
-        var service = CreateService(out var database);
-        await using var _ = database;
         var key = $"tests/{Guid.NewGuid():N}/round-trip.txt";
         var content = "hello seaweedfs"u8.ToArray();
 
@@ -45,8 +51,6 @@ public sealed class StorageServiceTests(InfrastructureTestFixture fixture)
     [Fact]
     public async Task HeadObjectAsync_ExistingObject_ReturnsMetadata()
     {
-        var service = CreateService(out var database);
-        await using var _ = database;
         var key = $"tests/{Guid.NewGuid():N}/head.txt";
         await service.UploadFileAsync(new MemoryStream("x"u8.ToArray()), "text/plain", InfrastructureTestFixture.S3Bucket, key, CancellationToken.None);
 
@@ -59,9 +63,6 @@ public sealed class StorageServiceTests(InfrastructureTestFixture fixture)
     [Fact]
     public async Task HeadObjectAsync_MissingObject_ReturnsNull()
     {
-        var service = CreateService(out var database);
-        await using var _ = database;
-
         var metadata = await service.HeadObjectAsync(InfrastructureTestFixture.S3Bucket, $"tests/{Guid.NewGuid():N}/missing.txt", CancellationToken.None);
 
         Assert.Null(metadata);
@@ -70,8 +71,6 @@ public sealed class StorageServiceTests(InfrastructureTestFixture fixture)
     [Fact]
     public async Task RemoveFileAsync_ExistingObject_DeletesIt()
     {
-        var service = CreateService(out var database);
-        await using var _ = database;
         var key = $"tests/{Guid.NewGuid():N}/to-remove.txt";
         await service.UploadFileAsync(new MemoryStream("x"u8.ToArray()), "text/plain", InfrastructureTestFixture.S3Bucket, key, CancellationToken.None);
 
@@ -83,8 +82,6 @@ public sealed class StorageServiceTests(InfrastructureTestFixture fixture)
     [Fact]
     public async Task CopyFileAsync_CopiesToTheDestinationKey()
     {
-        var service = CreateService(out var database);
-        await using var _ = database;
         var sourceKey = $"tests/{Guid.NewGuid():N}/source.txt";
         var destinationKey = $"tests/{Guid.NewGuid():N}/destination.txt";
         await service.UploadFileAsync(new MemoryStream("copy-me"u8.ToArray()), "text/plain", InfrastructureTestFixture.S3Bucket, sourceKey, CancellationToken.None);
@@ -97,8 +94,6 @@ public sealed class StorageServiceTests(InfrastructureTestFixture fixture)
     [Fact]
     public async Task ListObjectsAsync_ReturnsEveryObjectUnderThePrefix()
     {
-        var service = CreateService(out var database);
-        await using var _ = database;
         var prefix = $"tests/{Guid.NewGuid():N}";
         await service.UploadFileAsync(new MemoryStream("a"u8.ToArray()), "text/plain", InfrastructureTestFixture.S3Bucket, $"{prefix}/a.txt", CancellationToken.None);
         await service.UploadFileAsync(new MemoryStream("b"u8.ToArray()), "text/plain", InfrastructureTestFixture.S3Bucket, $"{prefix}/b.txt", CancellationToken.None);
@@ -113,8 +108,6 @@ public sealed class StorageServiceTests(InfrastructureTestFixture fixture)
     [Fact]
     public async Task RemoveFolderAsync_DeletesEveryObjectUnderThePrefix()
     {
-        var service = CreateService(out var database);
-        await using var _ = database;
         var prefix = $"tests/{Guid.NewGuid():N}";
         await service.UploadFileAsync(new MemoryStream("a"u8.ToArray()), "text/plain", InfrastructureTestFixture.S3Bucket, $"{prefix}/a.txt", CancellationToken.None);
         await service.UploadFileAsync(new MemoryStream("b"u8.ToArray()), "text/plain", InfrastructureTestFixture.S3Bucket, $"{prefix}/nested/b.txt", CancellationToken.None);
@@ -130,8 +123,6 @@ public sealed class StorageServiceTests(InfrastructureTestFixture fixture)
     [Fact]
     public async Task GetUploadUrlAsync_PresignedPut_CanActuallyUploadTheObject()
     {
-        var service = CreateService(out var database);
-        await using var _ = database;
         var key = $"tests/{Guid.NewGuid():N}/presigned.txt";
 
         var uploadUrl = await service.GetUploadUrlAsync(
@@ -145,15 +136,14 @@ public sealed class StorageServiceTests(InfrastructureTestFixture fixture)
             // signs Content-Type byte-for-byte) and the server answers 403 SignatureDoesNotMatch.
             Content = new ByteArrayContent(Encoding.UTF8.GetBytes("presigned content"))
         };
-        request.Content.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("text/plain");
+        request.Content.Headers.ContentType = new MediaTypeHeaderValue("text/plain");
         // GetUploadUrlAsync defaults preventOverwrite to true, which signs the URL together with
         // this header (see StorageService.GetUploadUrlAsync) — the actual PUT has to send it too,
         // or the signature no longer matches and the server answers 403.
         request.Headers.TryAddWithoutValidation("If-None-Match", "*");
         var response = await httpClient.SendAsync(request);
-        var responseBody = await response.Content.ReadAsStringAsync();
 
-        Assert.True(response.StatusCode == HttpStatusCode.OK, $"status={response.StatusCode}, body={responseBody}");
+        Assert.Equal(HttpStatusCode.OK, response.StatusCode);
         var metadata = await service.HeadObjectAsync(InfrastructureTestFixture.S3Bucket, key, CancellationToken.None);
         Assert.NotNull(metadata);
         Assert.Equal("presigned content".Length, metadata.ContentLength);