Add failing test for the case of sideposting with lid

packages/-ember-data/tests/integration/identifiers/lid-reflection-test.ts

@@ -1,11 +1,11 @@
 import { module, test } from 'qunit';
-import { defer } from 'rsvp';
+import { defer, resolve } from 'rsvp';
 
 import { setupTest } from 'ember-qunit';
 
 import Adapter from '@ember-data/adapter';
 import { RECORD_DATA_STATE } from '@ember-data/canary-features';
-import Model, { attr } from '@ember-data/model';
+import Model, { attr, belongsTo, hasMany } from '@ember-data/model';
 import Serializer from '@ember-data/serializer';
 import Store, { recordIdentifierFor } from '@ember-data/store';
 
@@ -145,4 +145,78 @@ module('Integration | Identifiers - lid reflection', function(hooks) {
 
     assert.strictEqual(record.name, '@runspired', 'After we finish we use the most recent clean name');
   });
+
+  test('lid works for sideposting scenario', async function(assert) {
+    class Ingredient extends Model {
+      @attr name;
+      @belongsTo('cake') cake;
+    }
+
+    class Cake extends Model {
+      @attr name;
+      @hasMany('ingredient', { async: false }) ingredients;
+    }
+
+    this.owner.register('model:ingredient', Ingredient);
+    this.owner.register('model:cake', Cake);
+
+    class TestSerializer extends Serializer {
+      normalizeResponse(_, __, payload) {
+        return payload;
+      }
+    }
+    class TestAdapter extends Adapter {
+      createRecord(store, ModelClass, snapshot) {
+        return resolve({
+          data: {
+            type: 'cake',
+            id: '1',
+            attributes: {
+              name: 'Cheesecake',
+            },
+            relationships: {
+              ingredients: {
+                data: [
+                  {
+                    type: 'ingredient',
+                    id: '2',
+                  },
+                ],
+              },
+            },
+          },
+          included: [
+            {
+              type: 'ingredient',
+              id: '2',
+              lid: cheeseIdentifier.lid,
+              attributes: {
+                name: 'Cheese',
+              },
+              relationships: {
+                cake: {
+                  data: {
+                    type: 'cake',
+                    id: '1',
+                  },
+                },
+              },
+            },
+          ],
+        });
+      }
+    }
+    this.owner.register('serializer:application', TestSerializer);
+    this.owner.register('adapter:application', TestAdapter);
+
+    const cheese = store.createRecord('ingredient', { name: 'Cheese' });
+    const cake = store.createRecord('cake', { name: 'Cheesecake', ingredients: [cheese] });
+
+    const cheeseIdentifier = recordIdentifierFor(cheese);
+
+    await cake.save();
+
+    assert.deepEqual(cake.hasMany('ingredients').ids(), ['2']);
+    assert.equal(cake.ingredients.objectAt(0).name, 'Cheese');
+  });
 });