Add WordRepository integration tests with embedded MongoDB

.github/workflows/backend.yml

@@ -41,7 +41,6 @@ jobs:
             dc.services.visualstudio.com:443
             deb.debian.org:80
             github.com:443
-            md-hdd-t032zjxllntc.z26.blob.storage.azure.net:443
             objects.githubusercontent.com:443
       - name: Checkout repository
         uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1

Backend.Tests/Backend.Tests.csproj

@@ -13,6 +13,9 @@
     <NoWarn>$(NoWarn);CA1305;CA1859;CS1591</NoWarn>
   </PropertyGroup>
   <ItemGroup>
+    <PackageReference Include="EphemeralMongo7.runtime.linux-x64" Version="2.0.0" Condition="$([MSBuild]::IsOSPlatform('Linux'))" />
+    <PackageReference Include="EphemeralMongo7.runtime.osx-arm64" Version="2.0.0" Condition="$([MSBuild]::IsOSPlatform('OSX'))" />
+    <PackageReference Include="EphemeralMongo7.runtime.win-x64" Version="2.0.0" Condition="$([MSBuild]::IsOSPlatform('Windows'))" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.0.1" />
     <PackageReference Include="Moq.Contrib.HttpClient" Version="1.4.0" />
     <PackageReference Include="NUnit" Version="4.4.0" />

Backend.Tests/Repositories/MongoDbTestRunner.cs

@@ -0,0 +1,213 @@
+using System;
+using System.Diagnostics;
+using System.IO;
+using System.Net.Sockets;
+using System.Runtime.InteropServices;
+using System.Threading;
+using MongoDB.Bson;
+using MongoDB.Driver;
+
+namespace Backend.Tests.Repositories
+{
+    /// <summary>
+    /// Starts and manages an ephemeral MongoDB process for integration testing.
+    /// Uses the mongod binary from the EphemeralMongo7 NuGet package.
+    /// Supports single-node replica sets to enable multi-document transactions.
+    /// </summary>
+    internal sealed class MongoDbTestRunner : IDisposable
+    {
+        private const string Host = "127.0.0.1";
+        private const string ReplicaSetName = "rs0";
+
+        private readonly Process _process;
+        private readonly string _dataDirectory;
+
+        public string ConnectionString { get; }
+
+        private MongoDbTestRunner(Process process, string dataDirectory, string connectionString)
+        {
+            _process = process;
+            _dataDirectory = dataDirectory;
+            ConnectionString = connectionString;
+        }
+
+        /// <summary>
+        /// Starts a MongoDB instance as a single-node replica set.
+        /// </summary>
+        public static MongoDbTestRunner Start()
+        {
+            var binaryPath = FindMongodBinary();
+            var port = FindFreePort();
+            var dataDirectory = Path.Combine(Path.GetTempPath(), $"mongo-test-{Guid.NewGuid():N}");
+            Directory.CreateDirectory(dataDirectory);
+
+            var process = StartMongodProcess(binaryPath, port, dataDirectory);
+            try
+            {
+                WaitForMongoReady(port);
+                InitializeReplicaSet(port);
+                WaitForReplicaSetReady(port);
+            }
+            catch
+            {
+                process.Kill(entireProcessTree: true);
+                process.Dispose();
+                Directory.Delete(dataDirectory, recursive: true);
+                throw;
+            }
+
+            var connectionString = $"mongodb://{Host}:{port}/?directConnection=true&replicaSet={ReplicaSetName}";
+            return new MongoDbTestRunner(process, dataDirectory, connectionString);
+        }
+
+        private static string FindMongodBinary()
+        {
+            var rid = GetRuntimeId();
+            var baseDir = AppContext.BaseDirectory;
+            var binaryName = RuntimeInformation.IsOSPlatform(OSPlatform.Windows) ? "mongod.exe" : "mongod";
+            var binaryPath = Path.Combine(baseDir, "runtimes", rid, "native", "mongodb", "bin", binaryName);
+
+            if (!File.Exists(binaryPath))
+            {
+                throw new FileNotFoundException(
+                    $"mongod binary not found at '{binaryPath}'. Ensure one of the EphemeralMongo7.runtime.* packages is installed.",
+                    binaryPath);
+            }
+
+            if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            {
+                // Ensure the binary is executable on Unix
+                var chmod = Process.Start(new ProcessStartInfo("chmod")
+                {
+                    ArgumentList = { "+x", binaryPath },
+                    UseShellExecute = false,
+                });
+                chmod?.WaitForExit();
+            }
+
+            return binaryPath;
+        }
+
+        private static string GetRuntimeId()
+        {
+            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows)) return "win-x64";
+            if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux)) return "linux-x64";
+            // EphemeralMongo7 only provides an arm64 binary for macOS
+            if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX)) return "osx-arm64";
+            throw new PlatformNotSupportedException("Unsupported operating system.");
+        }
+
+        private static int FindFreePort()
+        {
+            using var socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
+            socket.Bind(new System.Net.IPEndPoint(System.Net.IPAddress.Loopback, 0));
+            return ((System.Net.IPEndPoint)socket.LocalEndPoint!).Port;
+        }
+
+        private static Process StartMongodProcess(string binaryPath, int port, string dataDirectory)
+        {
+            var args = string.Join(" ",
+                $"--replSet {ReplicaSetName}",
+                $"--bind_ip {Host}",
+                $"--port {port}",
+                $"--dbpath \"{dataDirectory}\"",
+                "--noauth",
+                "--quiet");
+
+            var process = new Process
+            {
+                StartInfo = new ProcessStartInfo(binaryPath, args)
+                {
+                    UseShellExecute = false,
+                    RedirectStandardOutput = true,
+                    RedirectStandardError = true,
+                }
+            };
+            process.Start();
+            process.BeginOutputReadLine();
+            process.BeginErrorReadLine();
+            return process;
+        }
+
+        private static void WaitForMongoReady(int port, int timeoutSeconds = 30)
+        {
+            var deadline = DateTime.UtcNow.AddSeconds(timeoutSeconds);
+            while (DateTime.UtcNow < deadline)
+            {
+                try
+                {
+                    using var socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
+                    socket.Connect(Host, port);
+                    return;
+                }
+                catch (SocketException)
+                {
+                    Thread.Sleep(200);
+                }
+            }
+
+            throw new TimeoutException($"MongoDB did not start within {timeoutSeconds} seconds on port {port}.");
+        }
+
+        private static void InitializeReplicaSet(int port)
+        {
+            var client = new MongoClient($"mongodb://{Host}:{port}/?directConnection=true");
+            var admin = client.GetDatabase("admin");
+            var config = new BsonDocument
+            {
+                { "_id", ReplicaSetName },
+                { "members", new BsonArray { new BsonDocument { { "_id", 0 }, { "host", $"{Host}:{port}" } } } }
+            };
+            admin.RunCommand<BsonDocument>(new BsonDocument("replSetInitiate", config));
+        }
+
+        private static void WaitForReplicaSetReady(int port, int timeoutSeconds = 30)
+        {
+            var client = new MongoClient(
+                $"mongodb://{Host}:{port}/?directConnection=true&replicaSet={ReplicaSetName}");
+            var deadline = DateTime.UtcNow.AddSeconds(timeoutSeconds);
+            Exception? lastException = null;
+            while (DateTime.UtcNow < deadline)
+            {
+                try
+                {
+                    var admin = client.GetDatabase("admin");
+                    var status = admin.RunCommand<BsonDocument>(new BsonDocument("replSetGetStatus", 1));
+                    if (status["ok"].ToInt32() == 1 && status["myState"].ToInt32() == 1)
+                    {
+                        return;
+                    }
+                }
+                catch (Exception ex)
+                {
+                    lastException = ex;
+                }
+
+                Thread.Sleep(500);
+            }
+
+            throw new TimeoutException(
+                $"Replica set did not become ready within {timeoutSeconds} seconds.", lastException);
+        }
+
+        public void Dispose()
+        {
+            try
+            {
+                if (!_process.HasExited)
+                {
+                    _process.Kill(entireProcessTree: true);
+                }
+            }
+            catch (InvalidOperationException) { }
+
+            _process.Dispose();
+
+            try
+            {
+                Directory.Delete(_dataDirectory, recursive: true);
+            }
+            catch (IOException) { }
+        }
+    }
+}