[TEST] Added test for issue emberjs#7265 (Self-Referent Relationship …

…in Save Response Blows Up Save).

Tests the case where a save-response returns a relationship that includes the self-id.
This passes in master, but is broken in 3.12 LTS

packages/-ember-data/tests/integration/relationships/belongs-to-test.js

@@ -26,6 +26,13 @@ module('integration/relationship/belongs-to BelongsTo Relationships (new-style)'
   let store;
   setupTest(hooks);
 
+  class Company extends Model {
+    @belongsTo('company', { inverse: null, async: true })
+    parentCompany;
+    @attr()
+    name;
+  };
+
   class Person extends Model {
     @belongsTo('pet', { inverse: 'bestHuman', async: true })
     bestDog;
@@ -44,7 +51,8 @@ module('integration/relationship/belongs-to BelongsTo Relationships (new-style)'
     let { owner } = this;
     owner.register('service:store', Store);
     owner.register('model:person', Person);
-    owner.register('model:pet', Pet);
+	owner.register('model:pet', Pet);
+    owner.register('model:company', Company);
     owner.register(
       'serializer:application',
       JSONAPISerializer.extend({
@@ -183,6 +191,34 @@ module('integration/relationship/belongs-to BelongsTo Relationships (new-style)'
     assert.ok(pirate.get('bestHuman') === null, 'scene 3 - pirate no longer has Chris as best human');
     assert.ok(bestDog === null, 'scene 3 - Chris has no best dog');
   });
+
+  test("belongsTo saving with relationship that references yourself doesn't blow up", async function(assert) {
+    this.owner.register(
+      'adapter:company',
+      JSONAPIAdapter.extend({
+        createRecord(store, type, snapshot) {
+          return resolve({
+            data: {
+              type: 'company',
+              id: '123',
+              attributes: { name: 'Acme Corporation' },
+              relationships: {
+                parentCompany: {
+                  data: { type: 'company', id: '123' }
+                },
+              },
+            },
+          });
+        }
+      })
+    );
+
+    let company = store.createRecord('company');
+    company.set('name', 'Acme Corporation');
+    company = await company.save();
+    assert.ok(company.id);
+    assert.equal(company.belongsTo('parentCompany').id(), company.id);
+  });
 });
 
 module('integration/relationship/belongs_to Belongs-To Relationships', function(hooks) {