Rejoin always setting + tests

lib/browser/mqtt5.spec.ts

@@ -383,6 +383,27 @@ test_utils.conditional_test(test_utils.ClientEnvironmentalConfig.hasIotCoreEnvir
     expect(settings.clientId).toEqual(clientId);
 });
 
+test_utils.conditional_test(test_utils.ClientEnvironmentalConfig.hasIotCoreEnvironment())('Negotiated settings - always rejoin session', async () => {
+    let clientId : string = `test-${uuid()}`;
+    let config : mqtt5.Mqtt5ClientConfig = createWsIotCoreClientConfig();
+    config.connectProperties = {
+        clientId: clientId,
+        keepAliveIntervalSeconds: 600,
+        sessionExpiryIntervalSeconds: 3600,
+    };
+
+    let client: mqtt5.Mqtt5Client = new mqtt5.Mqtt5Client(config);
+
+    // @ts-ignore
+    await test_utils.testNegotiatedSettings(client, false);
+
+    config.sessionBehavior = mqtt5.ClientSessionBehavior.RejoinAlways;
+    let forcedRejoinClient : mqtt5.Mqtt5Client = new mqtt5.Mqtt5Client(config);
+
+    // @ts-ignore
+    await test_utils.testNegotiatedSettings(forcedRejoinClient, true);
+});
+
 test_utils.conditional_test(test_utils.ClientEnvironmentalConfig.hasIotCoreEnvironment())('Sub - Pub QoS 0 - Unsub', async () => {
     let topic : string = `test-${uuid()}`;
     let testPayload : Buffer = Buffer.from("Derp", "utf-8");

lib/browser/mqtt5_utils.ts

@@ -119,7 +119,7 @@ export function getOrderedReconnectDelayBounds(configMin?: number, configMax?: n
 
 /** @internal */
 function should_mqtt_js_use_clean_start(session_behavior? : mqtt5.ClientSessionBehavior) : boolean {
-    return session_behavior !== mqtt5.ClientSessionBehavior.RejoinPostSuccess;
+    return session_behavior !== mqtt5.ClientSessionBehavior.RejoinPostSuccess && session_behavior !== mqtt5.ClientSessionBehavior.RejoinAlways;
 }
 
 /** @internal */

lib/common/mqtt5.ts

@@ -105,6 +105,14 @@ export enum ClientSessionBehavior {
      * Session rejoin requires an appropriate non-zero session expiry interval in the client's CONNECT options.
      */
     RejoinPostSuccess = 2,
+
+    /**
+     * Always attempt to rejoin an existing session.  Since the client does not yet support durable session persistence,
+     * this option is not guaranteed to be spec compliant because any unacknowledged qos1 publishes (which are
+     * part of the client session state) will not be present on the initial connection.  Until we support
+     * durable session resumption, this option is technically spec-breaking, but useful.
+     */
+    RejoinAlways = 3,
 }
 
 /**

lib/native/mqtt5.spec.ts

@@ -483,6 +483,23 @@ test_utils.conditional_test(test_utils.ClientEnvironmentalConfig.hasIotCoreEnvir
     expect(settings.clientId).toEqual(clientId);
 });
 
+test_utils.conditional_test(test_utils.ClientEnvironmentalConfig.hasIotCoreEnvironment())('Negotiated settings - always rejoin session', async () => {
+    let clientId : string = `test-${uuid()}`;
+    let config : mqtt5.Mqtt5ClientConfig = createDirectIotCoreClientConfig();
+    config.connectProperties = {
+        clientId: clientId,
+        keepAliveIntervalSeconds: 600,
+        sessionExpiryIntervalSeconds: 3600,
+    };
+
+    let client: mqtt5.Mqtt5Client = new mqtt5.Mqtt5Client(config);
+    await test_utils.testNegotiatedSettings(client, false);
+
+    config.sessionBehavior = mqtt5.ClientSessionBehavior.RejoinAlways;
+    let forcedRejoinClient : mqtt5.Mqtt5Client = new mqtt5.Mqtt5Client(config);
+    await test_utils.testNegotiatedSettings(forcedRejoinClient, true);
+});
+
 test_utils.conditional_test(test_utils.ClientEnvironmentalConfig.hasIotCoreEnvironment())('Sub - Pub QoS 0 - Unsub', async () => {
     let topic : string = `test-${uuid()}`;
     let testPayload : Buffer = Buffer.from("Derp", "utf-8");

test/mqtt5.ts

@@ -308,7 +308,7 @@ export async function testSubscribeValidationFailure(client : mqtt5.Mqtt5Client,
     client.close();
 }
 
-export function verifyCommonNegotiatedSettings(settings: mqtt5.NegotiatedSettings) {
+export function verifyCommonNegotiatedSettings(settings: mqtt5.NegotiatedSettings, expectedRejoinedSession: boolean) {
     expect(settings.maximumQos).toEqual(mqtt5.QoS.AtLeastOnce);
     expect(settings.sessionExpiryInterval).toBeDefined();
     expect(settings.receiveMaximumFromServer).toBeDefined();
@@ -318,12 +318,12 @@ export function verifyCommonNegotiatedSettings(settings: mqtt5.NegotiatedSetting
     expect(typeof settings.wildcardSubscriptionsAvailable === 'boolean').toBeTruthy();
     expect(typeof settings.subscriptionIdentifiersAvailable === 'boolean').toBeTruthy();
     expect(typeof settings.sharedSubscriptionsAvailable === 'boolean').toBeTruthy();
-    expect(settings.rejoinedSession).toBeFalsy();
+    expect(settings.rejoinedSession).toEqual(expectedRejoinedSession);
     expect(settings.clientId).toBeDefined();
     expect(settings.sessionExpiryInterval).toBeDefined();
 }
 
-export async function testNegotiatedSettings(client: mqtt5.Mqtt5Client) : Promise<mqtt5.NegotiatedSettings> {
+export async function testNegotiatedSettings(client: mqtt5.Mqtt5Client, expectedRejoinedSession?: boolean) : Promise<mqtt5.NegotiatedSettings> {
     let connectionSuccess = once(client, mqtt5.Mqtt5Client.CONNECTION_SUCCESS);
     let stopped = once(client, mqtt5.Mqtt5Client.STOPPED)
 
@@ -338,7 +338,7 @@ export async function testNegotiatedSettings(client: mqtt5.Mqtt5Client) : Promis
 
             client.close();
 
-            verifyCommonNegotiatedSettings(connectionSuccessEvent.settings);
+            verifyCommonNegotiatedSettings(connectionSuccessEvent.settings, expectedRejoinedSession ?? false);
 
             resolve(connectionSuccessEvent.settings);
         } catch (err) {