fix(store): add Signal equal function for immutable object comparison (…

…#3883)

Co-authored-by: Brandon Roberts <robertsbt@gmail.com>
Co-authored-by: Marko Stanimirović <markostanimirovic95@gmail.com>

modules/store/spec/integration_signals.spec.ts

@@ -12,6 +12,7 @@ import {
   VisibilityFilters,
   resetId,
 } from './fixtures/todos';
+import { computed } from '@angular/core';
 
 interface Todo {
   id: number;
@@ -130,4 +131,26 @@ describe('NgRx and Signals Integration spec', () => {
       expect(error).toBeUndefined();
     });
   });
+
+  describe('immutable state integration spec', () => {
+    it('Store.selectSignal should not trigger on unrelated global state changes', () => {
+      let todosTriggerCount = 0;
+
+      const todos = store.selectSignal((state) => state.todos);
+
+      const todosTriggerState = computed(() => {
+        todos();
+        return ++todosTriggerCount;
+      });
+
+      store.dispatch({ type: ADD_TODO, payload: { text: 'first todo' } });
+      expect(todosTriggerState()).toBe(1);
+
+      store.dispatch({
+        type: SET_VISIBILITY_FILTER,
+        payload: VisibilityFilters.SHOW_ACTIVE,
+      });
+      expect(todosTriggerState()).toBe(1);
+    });
+  });
 });

modules/store/src/store.ts

@@ -114,7 +114,9 @@ export class Store<T = object>
     selector: (state: T) => K,
     options?: SelectSignalOptions<K>
   ): Signal<K> {
-    return computed(() => selector(this.state()), { equal: options?.equal });
+    return computed(() => selector(this.state()), {
+      equal: options?.equal || ((previous, current) => previous === current),
+    });
   }
 
   override lift<R>(operator: Operator<T, R>): Store<R> {