fix: A(PromiseManyArray) should have no-effect

packages/-ember-data/tests/integration/relationships/promise-many-array-test.js

@@ -0,0 +1,39 @@
+import { A } from '@ember/array';
+import { w } from '@ember/string';
+
+import { module, test } from 'qunit';
+
+import { setupRenderingTest } from 'ember-qunit';
+
+import Model, { attr, hasMany } from '@ember-data/model';
+
+module('PromiseManyArray side-affected by EmberArray', (hooks) => {
+  setupRenderingTest(hooks);
+
+  test('PromiseManyArray is not side-affected by EmberArray', async function (assert) {
+    const { owner } = this;
+    class Person extends Model {
+      @attr('string') name;
+    }
+    class Group extends Model {
+      @hasMany('person', { inverse: null }) members;
+    }
+    owner.register('model:person', Person);
+    owner.register('model:group', Group);
+    const store = owner.lookup('service:store');
+    const members = w('Bob John Michael Larry Lucy').map((name) => store.createRecord('person', { name }));
+    const group = store.createRecord('group', { members });
+
+    const replaceFn = group.members.replace;
+    assert.strictEqual(group.members.length, 5, 'initial length is correct');
+
+    group.members.replace(0, 1);
+    assert.strictEqual(group.members.length, 4, 'updated length is correct');
+
+    A(group.members);
+
+    assert.strictEqual(replaceFn, group.members.replace, 'we have the same function for replace');
+    group.members.replace(0, 1);
+    assert.strictEqual(group.members.length, 3, 'updated length is correct');
+  });
+});

packages/model/addon/-private/system/promise-many-array.ts

@@ -1,3 +1,4 @@
+import ArrayMixin from '@ember/array';
 import { assert } from '@ember/debug';
 import { dependentKeyCompat } from '@ember/object/compat';
 import { tracked } from '@glimmer/tracking';
@@ -16,7 +17,7 @@ import { DEPRECATE_EVENTED_API_USAGE } from '@ember-data/private-build-infra/dep
 
   A PromiseManyArray is an array-like proxy that also proxies certain method calls
   to the underlying ManyArray in addition to being "promisified".
-   
+
   Right now we proxy:
 
     * `reload()`
@@ -41,6 +42,14 @@ export default class PromiseManyArray {
     this._update(promise, content);
     this.isDestroyed = false;
     this.isDestroying = false;
+
+    const meta = Ember.meta(this);
+    meta.hasMixin = (mixin: Object) => {
+      if (mixin === ArrayMixin) {
+        return true;
+      }
+      return false;
+    };
   }
 
   //---- Methods/Properties on ArrayProxy that we will keep as our API

packages/store/types/ember/index.d.ts

@@ -2,3 +2,4 @@ export function run(callback: Function);
 export const ENV: {
   DS_WARN_ON_UNKNOWN_KEYS?: boolean;
 };
+export function meta(obj: Object): any;