From 9a95f0c0f9a47e0143fba8e69ab998a1221b01ef Mon Sep 17 00:00:00 2001
From: gnuxie <Gnuxie@protonmail.com>
Date: Sun, 2 Feb 2025 13:55:48 +0000
Subject: [PATCH 1/3] Make leaveEvent processing code clearer.

I'm not sure wtf was going on with that if but i think it always
returned early no matter what, so i have changed it to do what
i think it is trying to do.

Ban events used to be ignored for sure.
---
 src/MatrixClient.ts | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/src/MatrixClient.ts b/src/MatrixClient.ts
index dbef443d..6585c169 100644
--- a/src/MatrixClient.ts
+++ b/src/MatrixClient.ts
@@ -827,17 +827,16 @@ export class MatrixClient extends EventEmitter {
             for (const event of room['timeline']['events']) {
                 if (event['type'] !== 'm.room.member') continue;
                 if (event['state_key'] !== await this.getUserId()) continue;
-
-                const membership = event["content"]?.["membership"];
-                if (membership !== "leave" && membership !== "ban") continue;
-
-                const oldAge = leaveEvent && leaveEvent['unsigned'] && leaveEvent['unsigned']['age'] ? leaveEvent['unsigned']['age'] : 0;
-                const newAge = event['unsigned'] && event['unsigned']['age'] ? event['unsigned']['age'] : 0;
-                if (leaveEvent && oldAge < newAge) continue;
-
-                leaveEvent = event;
+                switch (event["content"]?.["membership"]) {
+                    case "leave":
+                    case "ban": {
+                        const oldAge = leaveEvent && leaveEvent['unsigned'] && leaveEvent['unsigned']['age'] ? leaveEvent['unsigned']['age'] : 0;
+                        const newAge = event['unsigned'] && event['unsigned']['age'] ? event['unsigned']['age'] : 0;
+                        if (leaveEvent && oldAge < newAge) continue;
+                        leaveEvent = event;
+                    }
+                }
             }
-
             if (!leaveEvent) {
                 LogService.warn("MatrixClientLite", "Left room " + roomId + " without receiving an event");
                 continue;

From 5de1a9bd3d579de2b3d22d9d01dc8f287ae79299 Mon Sep 17 00:00:00 2001
From: gnuxie <Gnuxie@protonmail.com>
Date: Sun, 2 Feb 2025 13:57:52 +0000
Subject: [PATCH 2/3] Upgrade a warning about missing leave/ban event to error.

If the client isn't alerted to leaving a room this can be pretty
serious and represents a flaw in the SDK.
---
 src/MatrixClient.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/MatrixClient.ts b/src/MatrixClient.ts
index 6585c169..b7e303ff 100644
--- a/src/MatrixClient.ts
+++ b/src/MatrixClient.ts
@@ -838,7 +838,7 @@ export class MatrixClient extends EventEmitter {
                 }
             }
             if (!leaveEvent) {
-                LogService.warn("MatrixClientLite", "Left room " + roomId + " without receiving an event");
+                LogService.error("MatrixClientLite", "Left room " + roomId + " without receiving an event");
                 continue;
             }
 

From 7eb5d214d000944578c2c9e77bfd57ff2b84cd33 Mon Sep 17 00:00:00 2001
From: gnuxie <Gnuxie@protonmail.com>
Date: Sun, 2 Feb 2025 14:06:53 +0000
Subject: [PATCH 3/3] Add a test to verify `MatrixClient`'s `room.leave` emits
 on ban.

---
 test/MatrixClientTest.ts | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/test/MatrixClientTest.ts b/test/MatrixClientTest.ts
index 377d9ad1..6bc6b376 100644
--- a/test/MatrixClientTest.ts
+++ b/test/MatrixClientTest.ts
@@ -1457,6 +1457,35 @@ describe('MatrixClient', () => {
             expect(spy.callCount).toBe(1);
         });
 
+        it('should process banned rooms as left rooms', async () => {
+            const { client: realClient } = createTestClient();
+            const client = <ProcessSyncClient>(<any>realClient);
+
+            const userId = "@syncing:example.org";
+            const roomId = "!testing:example.org";
+            const events = [
+                {
+                    type: "m.room.member",
+                    state_key: userId,
+                    unsigned: { age: 0 },
+                    content: { membership: "ban" },
+                },
+            ];
+
+            client.userId = userId;
+
+            const spy = simple.stub().callFn((rid, ev) => {
+                expect(ev).toMatchObject(events[0]);
+                expect(rid).toEqual(roomId);
+            });
+            realClient.on("room.leave", spy);
+
+            const roomsObj = {};
+            roomsObj[roomId] = { timeline: { events: events } };
+            await client.processSync({ rooms: { leave: roomsObj } });
+            expect(spy.callCount).toBe(1);
+        });
+
         it('should process left rooms account data', async () => {
             const { client: realClient } = createTestClient();
             const client = <ProcessSyncClient>(<any>realClient);