feat: add MQTT will message delivery on abnormal disconnect (Gap 6.2)

Adds WillMessage class, SetWill/ClearWill/GetWill methods to MqttSessionStore, PublishWillMessage that dispatches via OnPublish delegate (or tracks as delayed when DelayIntervalSeconds > 0), and 10 unit tests covering all will message behaviors.
2026-02-25 11:38:43 -05:00
parent 18f0ca0587
commit a44ad4b7fc
4 changed files with 540 additions and 0 deletions
--- a/tests/NATS.Server.Tests/Mqtt/MqttFlowControllerTests.cs
+++ b/tests/NATS.Server.Tests/Mqtt/MqttFlowControllerTests.cs
@@ -0,0 +1,146 @@
+// Go reference: server/mqtt.go — mqttMaxAckPending, flow control logic.
+
+using NATS.Server.Mqtt;
+using Shouldly;
+
+namespace NATS.Server.Tests.Mqtt;
+
+public sealed class MqttFlowControllerTests
+{
+    // 1. TryAcquire succeeds when under limit
+    [Fact]
+    public async Task TryAcquire_succeeds_when_under_limit()
+    {
+        using var fc = new MqttFlowController(defaultMaxAckPending: 1024);
+
+        var result = await fc.TryAcquireAsync("sub-1");
+
+        result.ShouldBeTrue();
+    }
+
+    // 2. TryAcquire fails when at limit
+    [Fact]
+    public async Task TryAcquire_fails_when_at_limit()
+    {
+        using var fc = new MqttFlowController(defaultMaxAckPending: 1);
+
+        var first = await fc.TryAcquireAsync("sub-1");
+        var second = await fc.TryAcquireAsync("sub-1");
+
+        first.ShouldBeTrue();
+        second.ShouldBeFalse();
+    }
+
+    // 3. Release allows next acquire
+    [Fact]
+    public async Task Release_allows_next_acquire()
+    {
+        using var fc = new MqttFlowController(defaultMaxAckPending: 1);
+
+        var first = await fc.TryAcquireAsync("sub-1");
+        first.ShouldBeTrue();
+
+        // At limit — second should fail
+        var atLimit = await fc.TryAcquireAsync("sub-1");
+        atLimit.ShouldBeFalse();
+
+        fc.Release("sub-1");
+
+        // After release a slot is available again
+        var afterRelease = await fc.TryAcquireAsync("sub-1");
+        afterRelease.ShouldBeTrue();
+    }
+
+    // 4. GetPendingCount tracks pending
+    [Fact]
+    public async Task GetPendingCount_tracks_pending()
+    {
+        using var fc = new MqttFlowController(defaultMaxAckPending: 10);
+
+        await fc.AcquireAsync("sub-1");
+        await fc.AcquireAsync("sub-1");
+        await fc.AcquireAsync("sub-1");
+
+        fc.GetPendingCount("sub-1").ShouldBe(3);
+    }
+
+    // 5. GetPendingCount decrements on release
+    [Fact]
+    public async Task GetPendingCount_decrements_on_release()
+    {
+        using var fc = new MqttFlowController(defaultMaxAckPending: 10);
+
+        await fc.AcquireAsync("sub-1");
+        await fc.AcquireAsync("sub-1");
+        await fc.AcquireAsync("sub-1");
+
+        fc.Release("sub-1");
+
+        fc.GetPendingCount("sub-1").ShouldBe(2);
+    }
+
+    // 6. GetPendingCount returns zero for unknown subscription
+    [Fact]
+    public void GetPendingCount_zero_for_unknown()
+    {
+        using var fc = new MqttFlowController();
+
+        fc.GetPendingCount("does-not-exist").ShouldBe(0);
+    }
+
+    // 7. RemoveSubscription cleans up
+    [Fact]
+    public async Task RemoveSubscription_cleans_up()
+    {
+        using var fc = new MqttFlowController(defaultMaxAckPending: 10);
+
+        await fc.AcquireAsync("sub-1");
+        fc.SubscriptionCount.ShouldBe(1);
+
+        fc.RemoveSubscription("sub-1");
+
+        fc.SubscriptionCount.ShouldBe(0);
+    }
+
+    // 8. SubscriptionCount tracks independent subscriptions
+    [Fact]
+    public async Task SubscriptionCount_tracks_subscriptions()
+    {
+        using var fc = new MqttFlowController(defaultMaxAckPending: 10);
+
+        await fc.AcquireAsync("sub-a");
+        await fc.AcquireAsync("sub-b");
+        await fc.AcquireAsync("sub-c");
+
+        fc.SubscriptionCount.ShouldBe(3);
+    }
+
+    // 9. DefaultMaxAckPending can be updated via UpdateLimit
+    [Fact]
+    public void DefaultMaxAckPending_can_be_updated()
+    {
+        using var fc = new MqttFlowController(defaultMaxAckPending: 1024);
+        fc.DefaultMaxAckPending.ShouldBe(1024);
+
+        fc.UpdateLimit(512);
+
+        fc.DefaultMaxAckPending.ShouldBe(512);
+    }
+
+    // 10. Dispose cleans up all subscriptions
+    [Fact]
+    public async Task Dispose_cleans_up_all()
+    {
+        var fc = new MqttFlowController(defaultMaxAckPending: 10);
+
+        await fc.AcquireAsync("sub-x");
+        await fc.AcquireAsync("sub-y");
+        await fc.AcquireAsync("sub-z");
+
+        fc.SubscriptionCount.ShouldBe(3);
+
+        fc.Dispose();
+
+        fc.SubscriptionCount.ShouldBe(0);
+    }
+}