From 4ad91fa3cd554285fd4e84b34a868f7ac3b729f1 Mon Sep 17 00:00:00 2001
From: ersimont <8042088+ersimont@users.noreply.github.com>
Date: Mon, 15 Jul 2019 16:05:46 -0400
Subject: [PATCH] fix: observables were not emitting properly when the number
 of subscribers changed mid-emit

---
 projects/ng-app-state/src/lib/store-object.spec.ts  | 13 +++++++++++++
 .../lib/tree-based-observable/observable-node.ts    |  2 +-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/projects/ng-app-state/src/lib/store-object.spec.ts b/projects/ng-app-state/src/lib/store-object.spec.ts
index 91581d4..20f8a3b 100644
--- a/projects/ng-app-state/src/lib/store-object.spec.ts
+++ b/projects/ng-app-state/src/lib/store-object.spec.ts
@@ -190,6 +190,19 @@ describe("StoreObject", () => {
       counterStore.$.subscribe(spy);
       expectSingleCallAndReset(spy, 3);
     });
+
+    it("works when the number of subscribers changes mid-emit (production bug)", () => {
+      const spy = jasmine.createSpy();
+
+      store("counter")
+        .$.pipe(take(2))
+        .subscribe();
+      store("counter").$.subscribe(spy);
+      expectSingleCallAndReset(spy, 0);
+
+      store("counter").set(1);
+      expectSingleCallAndReset(spy, 1);
+    });
   });
 
   describe(".batch()", () => {
diff --git a/projects/ng-app-state/src/lib/tree-based-observable/observable-node.ts b/projects/ng-app-state/src/lib/tree-based-observable/observable-node.ts
index c751b3b..966d506 100644
--- a/projects/ng-app-state/src/lib/tree-based-observable/observable-node.ts
+++ b/projects/ng-app-state/src/lib/tree-based-observable/observable-node.ts
@@ -74,7 +74,7 @@ export class ObservableNode extends Observable<any> {
   }
 
   private emit() {
-    for (const subscriber of this.subscribers) {
+    for (const subscriber of this.subscribers.slice()) {
       subscriber.next(this.value);
     }
   }