feat: add room events

The adapter will now emit the following events:

- create-room (arg: room)
- delete-room (arg: room)
- join-room (args: room, sid)
- leave-room (args: room, sid)

Related: https://github.com/socketio/socket.io/issues/2897

lib/index.ts

@@ -59,8 +59,12 @@ export class Adapter extends EventEmitter {
 
       if (!this.rooms.has(room)) {
         this.rooms.set(room, new Set());
+        this.emit("create-room", room);
+      }
+      if (!this.rooms.get(room).has(id)) {
+        this.rooms.get(room).add(id);
+        this.emit("join-room", room, id);
       }
-      this.rooms.get(room).add(id);
     }
   }
 
@@ -75,9 +79,19 @@ export class Adapter extends EventEmitter {
       this.sids.get(id).delete(room);
     }
 
+    this._del(room, id);
+  }
+
+  private _del(room, id) {
     if (this.rooms.has(room)) {
-      this.rooms.get(room).delete(id);
-      if (this.rooms.get(room).size === 0) this.rooms.delete(room);
+      const deleted = this.rooms.get(room).delete(id);
+      if (deleted) {
+        this.emit("leave-room", room, id);
+      }
+      if (this.rooms.get(room).size === 0) {
+        this.rooms.delete(room);
+        this.emit("delete-room", room);
+      }
     }
   }
 
@@ -92,10 +106,7 @@ export class Adapter extends EventEmitter {
     }
 
     for (const room of this.sids.get(id)) {
-      if (this.rooms.has(room)) {
-        this.rooms.get(room).delete(id);
-        if (this.rooms.get(room).size === 0) this.rooms.delete(room);
-      }
+      this._del(room, id);
     }
 
     this.sids.delete(id);

test/index.js

@@ -57,4 +57,88 @@ describe("socket.io-adapter", () => {
     expect(rooms.size).to.be(2);
     expect(adapter.socketRooms("s4")).to.be(undefined);
   });
+
+  describe("events", () => {
+    it("should emit a 'create-room' event", done => {
+      const adapter = new Adapter({ server: { encoder: null } });
+      adapter.on("create-room", room => {
+        expect(room).to.eql("r1");
+        done();
+      });
+      adapter.addAll("s1", new Set(["r1"]));
+    });
+
+    it("should not emit a 'create-room' event if the room already exists", done => {
+      const adapter = new Adapter({ server: { encoder: null } });
+      adapter.addAll("s1", new Set(["r1"]));
+      adapter.on("create-room", room => {
+        done(new Error("should not happen"));
+      });
+      adapter.addAll("s2", new Set(["r1"]));
+      done();
+    });
+
+    it("should emit a 'join-room' event", done => {
+      const adapter = new Adapter({ server: { encoder: null } });
+      adapter.on("join-room", (room, sid) => {
+        expect(room).to.eql("r1");
+        expect(sid).to.eql("s1");
+        done();
+      });
+      adapter.addAll("s1", new Set(["r1"]));
+    });
+
+    it("should not emit a 'join-room' event if the sid is already in the room", done => {
+      const adapter = new Adapter({ server: { encoder: null } });
+      adapter.addAll("s1", new Set(["r1", "r2"]));
+      adapter.on("join-room", () => {
+        done(new Error("should not happen"));
+      });
+      adapter.addAll("s1", new Set(["r1"]));
+      done();
+    });
+
+    it("should emit a 'leave-room' event with del method", done => {
+      const adapter = new Adapter({ server: { encoder: null } });
+      adapter.on("leave-room", (room, sid) => {
+        expect(room).to.eql("r1");
+        expect(sid).to.eql("s1");
+        done();
+      });
+      adapter.addAll("s1", new Set(["r1"]));
+      adapter.del("s1", "r1");
+    });
+
+    it("should emit a 'leave-room' event with delAll method", done => {
+      const adapter = new Adapter({ server: { encoder: null } });
+      adapter.on("leave-room", (room, sid) => {
+        expect(room).to.eql("r1");
+        expect(sid).to.eql("s1");
+        done();
+      });
+      adapter.addAll("s1", new Set(["r1"]));
+      adapter.delAll("s1");
+    });
+
+    it("should emit a 'delete-room' event", done => {
+      const adapter = new Adapter({ server: { encoder: null } });
+      adapter.on("delete-room", room => {
+        expect(room).to.eql("r1");
+        done();
+      });
+      adapter.addAll("s1", new Set(["r1"]));
+      adapter.delAll("s1");
+    });
+
+    it("should not emit a 'delete-room' event if there is another sid in the room", done => {
+      const adapter = new Adapter({ server: { encoder: null } });
+      adapter.on("delete-room", room => {
+        done(new Error("should not happen"));
+      });
+      adapter.addAll("s1", new Set(["r1"]));
+      adapter.addAll("s2", new Set(["r1", "r2"]));
+      adapter.delAll("s1");
+      done();
+    });
+  });
 });