test: add mqtt config parsing coverage

tests/NATS.Server.Tests/ConfigProcessorTests.cs

@@ -501,4 +501,112 @@ public class ConfigProcessorTests
         var opts = ConfigProcessor.ProcessConfigFile(TestDataPath("tls.conf"));
         opts.HasTls.ShouldBeTrue();
     }
+
+    // ─── MQTT config ────────────────────────────────────────────
+
+    [Fact]
+    public void MqttConf_ListenHostAndPort()
+    {
+        var opts = ConfigProcessor.ProcessConfigFile(TestDataPath("mqtt.conf"));
+        opts.Mqtt.ShouldNotBeNull();
+        opts.Mqtt!.Host.ShouldBe("10.0.0.1");
+        opts.Mqtt.Port.ShouldBe(1883);
+    }
+
+    [Fact]
+    public void MqttConf_NoAuthUser()
+    {
+        var opts = ConfigProcessor.ProcessConfigFile(TestDataPath("mqtt.conf"));
+        opts.Mqtt.ShouldNotBeNull();
+        opts.Mqtt!.NoAuthUser.ShouldBe("mqtt_default");
+    }
+
+    [Fact]
+    public void MqttConf_Authorization()
+    {
+        var opts = ConfigProcessor.ProcessConfigFile(TestDataPath("mqtt.conf"));
+        opts.Mqtt.ShouldNotBeNull();
+        opts.Mqtt!.Username.ShouldBe("mqtt_user");
+        opts.Mqtt.Password.ShouldBe("mqtt_pass");
+        opts.Mqtt.Token.ShouldBe("mqtt_token");
+        opts.Mqtt.AuthTimeout.ShouldBe(3.0);
+    }
+
+    [Fact]
+    public void MqttConf_Tls()
+    {
+        var opts = ConfigProcessor.ProcessConfigFile(TestDataPath("mqtt.conf"));
+        opts.Mqtt.ShouldNotBeNull();
+        opts.Mqtt!.TlsCert.ShouldBe("/path/to/mqtt-cert.pem");
+        opts.Mqtt.TlsKey.ShouldBe("/path/to/mqtt-key.pem");
+        opts.Mqtt.TlsCaCert.ShouldBe("/path/to/mqtt-ca.pem");
+        opts.Mqtt.TlsVerify.ShouldBeTrue();
+        opts.Mqtt.TlsTimeout.ShouldBe(5.0);
+        opts.Mqtt.HasTls.ShouldBeTrue();
+    }
+
+    [Fact]
+    public void MqttConf_QosSettings()
+    {
+        var opts = ConfigProcessor.ProcessConfigFile(TestDataPath("mqtt.conf"));
+        opts.Mqtt.ShouldNotBeNull();
+        opts.Mqtt!.AckWait.ShouldBe(TimeSpan.FromSeconds(60));
+        opts.Mqtt.MaxAckPending.ShouldBe((ushort)2048);
+        opts.Mqtt.JsApiTimeout.ShouldBe(TimeSpan.FromSeconds(10));
+    }
+
+    [Fact]
+    public void MqttConf_JetStreamSettings()
+    {
+        var opts = ConfigProcessor.ProcessConfigFile(TestDataPath("mqtt.conf"));
+        opts.Mqtt.ShouldNotBeNull();
+        opts.Mqtt!.JsDomain.ShouldBe("mqtt-domain");
+        opts.Mqtt.StreamReplicas.ShouldBe(3);
+        opts.Mqtt.ConsumerReplicas.ShouldBe(1);
+        opts.Mqtt.ConsumerMemoryStorage.ShouldBeTrue();
+        opts.Mqtt.ConsumerInactiveThreshold.ShouldBe(TimeSpan.FromMinutes(5));
+    }
+
+    [Fact]
+    public void MqttConf_MaxAckPendingValidation_ReportsError()
+    {
+        var ex = Should.Throw<ConfigProcessorException>(() =>
+            ConfigProcessor.ProcessConfig("""
+                mqtt {
+                    max_ack_pending: 70000
+                }
+                """));
+        ex.Errors.ShouldContain(e => e.Contains("max_ack_pending"));
+    }
+
+    [Fact]
+    public void MqttConf_Aliases()
+    {
+        // Test alias keys: "ackwait" (alias for "ack_wait"), "net" (alias for "host"),
+        // "max_inflight" (alias for "max_ack_pending"), "consumer_auto_cleanup" (alias)
+        var opts = ConfigProcessor.ProcessConfig("""
+            mqtt {
+                net: "127.0.0.1"
+                port: 1884
+                ackwait: "45s"
+                max_inflight: 500
+                api_timeout: "8s"
+                consumer_auto_cleanup: "10m"
+            }
+            """);
+        opts.Mqtt.ShouldNotBeNull();
+        opts.Mqtt!.Host.ShouldBe("127.0.0.1");
+        opts.Mqtt.Port.ShouldBe(1884);
+        opts.Mqtt.AckWait.ShouldBe(TimeSpan.FromSeconds(45));
+        opts.Mqtt.MaxAckPending.ShouldBe((ushort)500);
+        opts.Mqtt.JsApiTimeout.ShouldBe(TimeSpan.FromSeconds(8));
+        opts.Mqtt.ConsumerInactiveThreshold.ShouldBe(TimeSpan.FromMinutes(10));
+    }
+
+    [Fact]
+    public void MqttConf_Absent_ReturnsNull()
+    {
+        var opts = ConfigProcessor.ProcessConfig("port: 4222");
+        opts.Mqtt.ShouldBeNull();
+    }
 }

tests/NATS.Server.Tests/TestData/mqtt.conf

@@ -0,0 +1,28 @@
+mqtt {
+    listen: "10.0.0.1:1883"
+    no_auth_user: "mqtt_default"
+
+    authorization {
+        user: "mqtt_user"
+        pass: "mqtt_pass"
+        token: "mqtt_token"
+        timeout: 3.0
+    }
+
+    tls {
+        cert_file: "/path/to/mqtt-cert.pem"
+        key_file: "/path/to/mqtt-key.pem"
+        ca_file: "/path/to/mqtt-ca.pem"
+        verify: true
+        timeout: 5.0
+    }
+
+    ack_wait: "60s"
+    max_ack_pending: 2048
+    js_domain: "mqtt-domain"
+    js_api_timeout: "10s"
+    stream_replicas: 3
+    consumer_replicas: 1
+    consumer_memory_storage: true
+    consumer_inactive_threshold: "5m"
+}