feat(ads/seo/release): v1.2.0 with live Google Ads, isolated ad profile, ads.txt, and SEO/AEO/GEO optimization

tests/Paca.Tests/Core/DirectDownloaderIntegrityGateTests.cs

@@ -0,0 +1,140 @@
+using System;
+using System.IO;
+using System.Net;
+using System.Net.Http;
+using System.Net.Http.Headers;
+using System.Security.Cryptography;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+using Paca.Core.Config;
+using Paca.Core.Hls;
+using Xunit;
+
+namespace Paca.Tests.Core;
+
+public class DirectDownloaderIntegrityGateTests : IDisposable
+{
+    private readonly string _testDir;
+
+    public DirectDownloaderIntegrityGateTests()
+    {
+        _testDir = Path.Combine(Path.GetTempPath(), "paca_direct_test_" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(_testDir);
+    }
+
+    public void Dispose()
+    {
+        try { if (Directory.Exists(_testDir)) Directory.Delete(_testDir, recursive: true); }
+        catch { }
+    }
+
+    [Fact]
+    public void Gate471_DirectDownloader_GuessExt_DetectsExtensions_FromUrlAndMediaType()
+    {
+        // Direct extension in URL
+        Assert.Equal(".mp4", DirectDownloader.GuessExt("", new Uri("https://paca.stream/video.mp4")));
+        Assert.Equal(".webm", DirectDownloader.GuessExt("", new Uri("https://paca.stream/clip.webm")));
+        Assert.Equal(".mkv", DirectDownloader.GuessExt("", new Uri("https://paca.stream/movie.mkv")));
+        Assert.Equal(".mp3", DirectDownloader.GuessExt("", new Uri("https://paca.stream/audio.mp3")));
+        Assert.Equal(".flac", DirectDownloader.GuessExt("", new Uri("https://paca.stream/track.flac")));
+
+        // Fallback from MIME ContentType
+        Assert.Equal(".mp4", DirectDownloader.GuessExt("video/mp4", new Uri("https://paca.stream/stream?id=123")));
+        Assert.Equal(".webm", DirectDownloader.GuessExt("video/webm", new Uri("https://paca.stream/stream?id=123")));
+        Assert.Equal(".m4a", DirectDownloader.GuessExt("audio/mp4", new Uri("https://paca.stream/stream?id=123")));
+    }
+
+    [Fact]
+    public async Task Gate472_DirectDownloader_VerifiesChecksum_WhenProvided_AndMatches()
+    {
+        var content = "PACA-DIRECT-DOWNLOAD-VERIFIED-DATA";
+        var bytes = Encoding.UTF8.GetBytes(content);
+        var sha256 = Convert.ToHexString(SHA256.HashData(bytes)).ToLowerInvariant();
+
+        var handler = new SimpleMockHttp(bytes);
+        using var client = new HttpClient(handler);
+        var config = new AppConfig();
+        var downloader = new DirectDownloader(client, config);
+
+        var outputBase = Path.Combine(_testDir, "test_success");
+        var resultPath = await downloader.DownloadAsync(
+            new Uri("https://paca.test/file.mp4"),
+            outputBase,
+            progress: null,
+            ct: CancellationToken.None,
+            expectedSha256: sha256
+        );
+
+        Assert.True(File.Exists(resultPath));
+        Assert.Equal(bytes.Length, new FileInfo(resultPath).Length);
+        Assert.False(File.Exists(outputBase + ".part"));
+    }
+
+    [Fact]
+    public async Task Gate473_DirectDownloader_ThrowsInvalidDataException_WhenChecksumMismatches()
+    {
+        var content = "TAMPERED-DATA-PAYLOAD";
+        var bytes = Encoding.UTF8.GetBytes(content);
+
+        var handler = new SimpleMockHttp(bytes);
+        using var client = new HttpClient(handler);
+        var config = new AppConfig();
+        var downloader = new DirectDownloader(client, config);
+
+        var outputBase = Path.Combine(_testDir, "test_corrupt");
+
+        await Assert.ThrowsAsync<InvalidDataException>(async () =>
+        {
+            await downloader.DownloadAsync(
+                new Uri("https://paca.test/file.mp4"),
+                outputBase,
+                progress: null,
+                ct: CancellationToken.None,
+                expectedSha256: "0000000000000000000000000000000000000000000000000000000000000000"
+            );
+        });
+    }
+
+    [Fact]
+    public async Task Gate474_DirectDownloader_AtomicPartCommit_CleansPartFile_UponCompletion()
+    {
+        var content = "PACA-ATOMIC-COMMIT-STREAM";
+        var bytes = Encoding.UTF8.GetBytes(content);
+
+        var handler = new SimpleMockHttp(bytes);
+        using var client = new HttpClient(handler);
+        var config = new AppConfig();
+        var downloader = new DirectDownloader(client, config);
+
+        var outputBase = Path.Combine(_testDir, "atomic_output");
+        var final = await downloader.DownloadAsync(
+            new Uri("https://paca.test/video.mp4"),
+            outputBase
+        );
+
+        Assert.True(File.Exists(final));
+        Assert.False(File.Exists(outputBase + ".part"));
+    }
+
+    private sealed class SimpleMockHttp : HttpMessageHandler
+    {
+        private readonly byte[] _data;
+
+        public SimpleMockHttp(byte[] data)
+        {
+            _data = data;
+        }
+
+        protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
+        {
+            var response = new HttpResponseMessage(HttpStatusCode.OK)
+            {
+                Content = new ByteArrayContent(_data)
+            };
+            response.Content.Headers.ContentType = new MediaTypeHeaderValue("video/mp4");
+            response.Content.Headers.ContentLength = _data.Length;
+            return Task.FromResult(response);
+        }
+    }
+}