fix(ffmpeg): point macOS at evermeet's ffprobe archive, not its ffmpeg one

listenarr.infrastructure/Ffmpeg/Installation/FfprobePlatformDefaults.cs

@@ -25,20 +25,49 @@ internal static class FfprobePlatformDefaults
         {
             if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
             {
-                if (RuntimeInformation.OSArchitecture == Architecture.Arm64)
-                {
-                    return "https://johnvansickle.com/ffmpeg/releases/ffmpeg-release-arm64-static.tar.xz";
-                }
-
-                return "https://johnvansickle.com/ffmpeg/releases/ffmpeg-release-amd64-static.tar.xz";
+                return GetDownloadUrl(OSPlatform.Linux, RuntimeInformation.OSArchitecture);
             }
 
             if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
             {
-                return "https://evermeet.cx/ffmpeg/ffmpeg-6.0.zip";
+                return GetDownloadUrl(OSPlatform.OSX, RuntimeInformation.OSArchitecture);
             }
 
             if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            {
+                return GetDownloadUrl(OSPlatform.Windows, RuntimeInformation.OSArchitecture);
+            }
+
+            return null;
+        }
+
+        /// <summary>
+        /// Resolves the archive URL for an explicit platform, so the mapping for every platform can
+        /// be asserted from a test host running on any one of them.
+        /// </summary>
+        /// <remarks>
+        /// Two constraints apply to anything returned here. The archive has to contain ffprobe:
+        /// the Linux and Windows builds ship a bundle carrying both binaries, but evermeet
+        /// publishes one binary per archive, so macOS needs the ffprobe archive and not the ffmpeg
+        /// one. The URL also has to end in a suffix <see cref="FfprobeArchiveExtractor"/>
+        /// recognises, which rules out endpoints that redirect to the current release without
+        /// naming a file.
+        /// </remarks>
+        internal static string? GetDownloadUrl(OSPlatform platform, Architecture architecture)
+        {
+            if (platform == OSPlatform.Linux)
+            {
+                return architecture == Architecture.Arm64
+                    ? "https://johnvansickle.com/ffmpeg/releases/ffmpeg-release-arm64-static.tar.xz"
+                    : "https://johnvansickle.com/ffmpeg/releases/ffmpeg-release-amd64-static.tar.xz";
+            }
+
+            if (platform == OSPlatform.OSX)
+            {
+                return "https://evermeet.cx/ffmpeg/ffprobe-6.0.zip";
+            }
+
+            if (platform == OSPlatform.Windows)
             {
                 return "https://www.gyan.dev/ffmpeg/builds/ffmpeg-release-essentials.zip";
             }

tests/Features/Infrastructure/Ffmpeg/Installation/FfprobePlatformDefaultsTests.cs

@@ -0,0 +1,113 @@
+/*
+ * Listenarr - Audiobook Management System
+ * Copyright (C) 2024-2026 Listenarr Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published
+ * by the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+using System.Runtime.InteropServices;
+
+// Aliased because `Listenarr.Tests.Features.Architecture` is an enclosing namespace here, and a
+// namespace member wins over the type of the same name.
+using Arch = System.Runtime.InteropServices.Architecture;
+
+namespace Listenarr.Tests.Features.Infrastructure.Ffmpeg.Installation
+{
+    [Trait("Name", "FfprobePlatformDefaultsTests")]
+    [Trait("Category", "FfmpegService")]
+    public class FfprobePlatformDefaultsTests
+    {
+        // Suffixes FfprobeArchiveExtractor dispatches on. A URL outside this set downloads fine and
+        // then extracts nothing, which is the failure mode that hid the macOS bug: the install log
+        // shows a successful download and no binary ever appears.
+        private static readonly string[] ExtractableSuffixes = [".zip", ".tar.xz", ".tar.gz", ".tgz"];
+
+        public static TheoryData<OSPlatform, Arch> AllPlatforms() => new()
+        {
+            { OSPlatform.Linux, Arch.X64 },
+            { OSPlatform.Linux, Arch.Arm64 },
+            { OSPlatform.OSX, Arch.X64 },
+            { OSPlatform.Windows, Arch.X64 },
+        };
+
+        [Theory]
+        [MemberData(nameof(AllPlatforms))]
+        [Trait("Method", "GetDownloadUrl")]
+        public void GetDownloadUrl_ReturnsAnArchiveTheExtractorCanOpen(
+            OSPlatform platform,
+            Arch architecture)
+        {
+            var url = FfprobePlatformDefaults.GetDownloadUrl(platform, architecture);
+
+            Assert.NotNull(url);
+            Assert.Contains(
+                ExtractableSuffixes,
+                suffix => url!.EndsWith(suffix, StringComparison.OrdinalIgnoreCase));
+        }
+
+        [Fact]
+        [Trait("Method", "GetDownloadUrl")]
+        public void GetDownloadUrl_ForMacOs_PointsAtTheFfprobeArchive()
+        {
+            // evermeet ships a separate archive per binary, so the ffmpeg archive contains no
+            // ffprobe at all and the install can never succeed on macOS.
+            var url = FfprobePlatformDefaults.GetDownloadUrl(OSPlatform.OSX, Arch.X64);
+
+            Assert.NotNull(url);
+            var fileName = url!.Split('/')[^1];
+            Assert.Contains("ffprobe", fileName, StringComparison.OrdinalIgnoreCase);
+        }
+
+        [Theory]
+        [MemberData(nameof(AllPlatforms))]
+        [Trait("Method", "GetDownloadUrl")]
+        public void GetDownloadUrl_IsServedOverHttps(OSPlatform platform, Arch architecture)
+        {
+            var url = FfprobePlatformDefaults.GetDownloadUrl(platform, architecture);
+
+            Assert.NotNull(url);
+            Assert.StartsWith("https://", url, StringComparison.OrdinalIgnoreCase);
+        }
+
+        [Fact]
+        [Trait("Method", "GetDownloadUrl")]
+        public void GetDownloadUrl_ForLinux_DistinguishesArm64FromX64()
+        {
+            var x64 = FfprobePlatformDefaults.GetDownloadUrl(OSPlatform.Linux, Arch.X64);
+            var arm64 = FfprobePlatformDefaults.GetDownloadUrl(OSPlatform.Linux, Arch.Arm64);
+
+            Assert.NotEqual(x64, arm64);
+            Assert.Contains("arm64", arm64!, StringComparison.OrdinalIgnoreCase);
+        }
+
+        [Fact]
+        [Trait("Method", "GetDownloadUrl")]
+        public void GetDownloadUrl_ForAnUnsupportedPlatform_ReturnsNull()
+        {
+            Assert.Null(FfprobePlatformDefaults.GetDownloadUrl(OSPlatform.FreeBSD, Arch.X64));
+        }
+
+        [Fact]
+        [Trait("Method", "GetDownloadUrl")]
+        public void GetDownloadUrl_WithoutArguments_MatchesTheHostPlatform()
+        {
+            var expected = FfprobePlatformDefaults.GetDownloadUrl(
+                OperatingSystem.IsWindows() ? OSPlatform.Windows
+                    : OperatingSystem.IsMacOS() ? OSPlatform.OSX
+                    : OSPlatform.Linux,
+                RuntimeInformation.OSArchitecture);
+
+            Assert.Equal(expected, FfprobePlatformDefaults.GetDownloadUrl());
+        }
+    }
+}