fix(external-system-gateway): resolve ExternalSystemGateway-004..010 — honour retry settings, dispose HTTP messages, fix URL building, truncate error bodies, fix connection leak

tests/ScadaLink.ExternalSystemGateway.Tests/DatabaseGatewayTests.cs

@@ -1,3 +1,5 @@
+using System.Data;
+using System.Data.Common;
 using Microsoft.Extensions.Logging.Abstractions;
 using NSubstitute;
 using ScadaLink.Commons.Entities.ExternalSystems;
@@ -75,4 +77,66 @@ public class DatabaseGatewayTests
 
         Assert.False(delivered); // permanent — the S&F engine parks the message
     }
+
+    // ── ExternalSystemGateway-010: SqlConnection must not leak when OpenAsync fails ──
+
+    [Fact]
+    public async Task GetConnection_OpenFails_DisposesConnectionBeforeRethrowing()
+    {
+        var conn = new DatabaseConnectionDefinition("testDb", "Server=localhost;Database=test") { Id = 1 };
+        _repository.GetAllDatabaseConnectionsAsync().Returns(new List<DatabaseConnectionDefinition> { conn });
+
+        var fake = new ThrowingDbConnection();
+        var gateway = new ConnectionFactoryStubGateway(_repository, fake);
+
+        await Assert.ThrowsAsync<InvalidOperationException>(
+            () => gateway.GetConnectionAsync("testDb"));
+
+        Assert.True(fake.WasDisposed, "The SqlConnection was leaked — it must be disposed when OpenAsync fails");
+    }
+
+    /// <summary>Test gateway that substitutes the connection factory with a stub.</summary>
+    private sealed class ConnectionFactoryStubGateway : DatabaseGateway
+    {
+        private readonly DbConnection _connection;
+
+        public ConnectionFactoryStubGateway(IExternalSystemRepository repository, DbConnection connection)
+            : base(repository, NullLogger<DatabaseGateway>.Instance) => _connection = connection;
+
+        internal override DbConnection CreateConnection(string connectionString) => _connection;
+    }
+
+    /// <summary>A DbConnection whose OpenAsync always fails, tracking whether it was disposed.</summary>
+    private sealed class ThrowingDbConnection : DbConnection
+    {
+        public bool WasDisposed { get; private set; }
+
+        public override Task OpenAsync(CancellationToken cancellationToken) =>
+            throw new InvalidOperationException("simulated open failure");
+        public override void Open() => throw new InvalidOperationException("simulated open failure");
+
+        protected override void Dispose(bool disposing)
+        {
+            if (disposing) WasDisposed = true;
+            base.Dispose(disposing);
+        }
+
+        public override ValueTask DisposeAsync()
+        {
+            WasDisposed = true;
+            return base.DisposeAsync();
+        }
+
+        // Unused abstract members.
+        [System.Diagnostics.CodeAnalysis.AllowNull]
+        public override string ConnectionString { get; set; } = string.Empty;
+        public override string Database => string.Empty;
+        public override string DataSource => string.Empty;
+        public override string ServerVersion => string.Empty;
+        public override ConnectionState State => ConnectionState.Closed;
+        public override void ChangeDatabase(string databaseName) => throw new NotSupportedException();
+        public override void Close() { }
+        protected override DbTransaction BeginDbTransaction(IsolationLevel il) => throw new NotSupportedException();
+        protected override DbCommand CreateDbCommand() => throw new NotSupportedException();
+    }
 }