Broadcast BotOfflineEvent async and ensure joinBroadcast works for it

mirai-core/src/commonMain/kotlin/QQAndroidBot.kt

@@ -11,9 +11,9 @@
 package net.mamoe.mirai.internal
 
 import kotlinx.atomicfu.atomic
-import kotlinx.coroutines.isActive
-import kotlinx.coroutines.runBlocking
+import kotlinx.coroutines.*
 import net.mamoe.mirai.Bot
+import net.mamoe.mirai.event.broadcast
 import net.mamoe.mirai.event.events.BotOfflineEvent
 import net.mamoe.mirai.event.events.BotOnlineEvent
 import net.mamoe.mirai.event.events.BotReloginEvent
@@ -148,7 +148,17 @@ internal open class QQAndroidBot constructor(
                     cause is BotClosedByEvent -> {}
                     else -> {
                         // any other unexpected exceptions considered as an error
-                        runBlocking { eventDispatcher.broadcast(BotOfflineEvent.Active(bot, cause)) }
+
+                        // When bot is closed, eventDispatcher.isActive will be false.
+                        // While in TestEventDispatcherImpl, eventDispatcher.isActive will always be true to enable catching the event.
+                        if (eventDispatcher.isActive) {
+                            eventDispatcher.broadcastAsync { BotOfflineEvent.Active(bot, cause) }
+                        } else {
+                            @OptIn(DelicateCoroutinesApi::class)
+                            GlobalScope.launch {
+                                BotOfflineEvent.Active(bot, cause).broadcast()
+                            }
+                        }
                     }
                 }
             },

mirai-core/src/commonMain/kotlin/network/components/EventDispatcher.kt

@@ -22,6 +22,8 @@ import kotlin.coroutines.EmptyCoroutineContext
  * All events will be caught and forwarded to [EventDispatcher]. Invocation of [Event.broadcast] and [EventDispatcher.broadcast] are effectively equal.
  */
 internal interface EventDispatcher {
+    val isActive: Boolean
+
     /**
      * Implement [Event.broadcast]
      */
@@ -91,6 +93,9 @@ internal open class EventDispatcherImpl(
         .addNameHierarchically("EventDispatcher")
         .childScope() {
 
+    override val isActive: Boolean
+        get() = this.coroutineContext.isActive
+
     override suspend fun broadcast(event: Event) {
         try {
             EventChannelToEventDispatcherAdapter.instance.callListeners(event)

mirai-core/src/commonTest/kotlin/network/framework/AbstractMockNetworkHandlerTest.kt

@@ -1,16 +1,17 @@
 /*
- * Copyright 2019-2021 Mamoe Technologies and contributors.
+ * Copyright 2019-2022 Mamoe Technologies and contributors.
  *
- *  此源代码的使用受 GNU AFFERO GENERAL PUBLIC LICENSE version 3 许可证的约束, 可以在以下链接找到该许可证.
- *  Use of this source code is governed by the GNU AGPLv3 license that can be found through the following link.
+ * 此源代码的使用受 GNU AFFERO GENERAL PUBLIC LICENSE version 3 许可证的约束, 可以在以下链接找到该许可证.
+ * Use of this source code is governed by the GNU AGPLv3 license that can be found through the following link.
  *
- *  https://github.com/mamoe/mirai/blob/master/LICENSE
+ * https://github.com/mamoe/mirai/blob/dev/LICENSE
  */
 
 @file:Suppress("MemberVisibilityCanBePrivate")
 
 package net.mamoe.mirai.internal.network.framework
 
+import kotlinx.coroutines.SupervisorJob
 import net.mamoe.mirai.Bot
 import net.mamoe.mirai.internal.MockBot
 import net.mamoe.mirai.internal.QQAndroidBot
@@ -45,7 +46,12 @@ internal abstract class AbstractMockNetworkHandlerTest : AbstractNetworkHandlerT
         set(SsoProcessor, TestSsoProcessor(bot))
         set(
             EventDispatcher,
-            TestEventDispatcherImpl(bot.coroutineContext, bot.logger.subLogger("TestEventDispatcherImpl"))
+            // Note that in real we use 'bot.coroutineContext', but here we override with a new, independent job
+            // to allow BotOfflineEvent.Active to be broadcast and joinBroadcast works even if bot coroutineScope is closed.
+            TestEventDispatcherImpl(
+                bot.coroutineContext + SupervisorJob(),
+                bot.logger.subLogger("TestEventDispatcherImpl")
+            )
         )
         set(
             StateObserver,

mirai-core/src/commonTest/kotlin/network/framework/AbstractRealNetworkHandlerTest.kt

@@ -9,6 +9,7 @@
 
 package net.mamoe.mirai.internal.network.framework
 
+import kotlinx.coroutines.SupervisorJob
 import net.mamoe.mirai.internal.BotAccount
 import net.mamoe.mirai.internal.MockAccount
 import net.mamoe.mirai.internal.MockConfiguration
@@ -131,7 +132,12 @@ internal sealed class AbstractRealNetworkHandlerTest<H : NetworkHandler> : Abstr
 
         set(
             EventDispatcher,
-            TestEventDispatcherImpl(bot.coroutineContext, bot.logger.subLogger("TestEventDispatcherImpl"))
+            // Note that in real we use 'bot.coroutineContext', but here we override with a new, independent job
+            // to allow BotOfflineEvent.Active to be broadcast and joinBroadcast works even if bot coroutineScope is closed.
+            TestEventDispatcherImpl(
+                bot.coroutineContext + SupervisorJob(),
+                bot.logger.subLogger("TestEventDispatcherImpl")
+            )
         )
         // set(StateObserver, bot.run { stateObserverChain() })
     }

mirai-core/src/commonTest/kotlin/network/framework/components/TestEventDispatcherImpl.kt

@@ -10,7 +10,6 @@
 package network.framework.components
 
 import kotlinx.coroutines.CoroutineStart
-import kotlinx.coroutines.isActive
 import kotlinx.coroutines.job
 import kotlinx.coroutines.launch
 import net.mamoe.mirai.event.Event