Make test context reusable during a test

In v2.0.0 @ember/test-helpers refactored to use
@ember/destroyable for teardown which also meant
that the application context was destroyed during
teardown, where previously it was only cleaned up
and the application was destroyed.

In our application tests we simulate a page
refresh by calling `teardownContext`` and
`setupContext`. The destroyable change broke this
functionality because the context is now marked
as destroyed.

This commit effectively reverts the change to use
@ember/destroyable and adds tests to ensure that
the context is not destroyed so that it can be
reset during a test.

Author: eliasdawson

addon/src/setup-context.ts

@@ -7,7 +7,7 @@ import type { Resolver } from '@ember/owner';
 import { setOwner } from '@ember/application';
 
 import buildOwner, { type Owner } from './build-owner.ts';
-import { _setupAJAXHooks, _teardownAJAXHooks } from './settled.ts';
+import { _setupAJAXHooks } from './settled.ts';
 import { _prepareOnerror } from './setup-onerror.ts';
 import Ember from 'ember';
 import {
@@ -19,10 +19,6 @@ import global from './global.ts';
 import { getResolver } from './resolver.ts';
 import { getApplication } from './application.ts';
 import getTestMetadata from './test-metadata.ts';
-import {
-  registerDestructor,
-  associateDestroyableChild,
-} from '@ember/destroyable';
 import {
   getDeprecationsForContext,
   getDeprecationsDuringCallbackForContext,
@@ -211,20 +207,6 @@ export function resumeTest(): void {
   context.resumeTest();
 }
 
-/**
-  @private
-  @param {Object} context the test context being cleaned up
-*/
-// eslint-disable-next-line @typescript-eslint/no-unused-vars
-function cleanup(context: BaseContext) {
-  _teardownAJAXHooks();
-
-  // SAFETY: this is intimate API *designed* for us to override.
-  (Ember as any).testing = false;
-
-  unsetContext();
-}
-
 /**
  * Returns deprecations which have occurred so far for a the current test context
  *
@@ -410,8 +392,6 @@ export default function setupContext<T extends object>(
 
   _backburner.DEBUG = true;
 
-  registerDestructor(context, cleanup);
-
   _prepareOnerror(context);
 
   return Promise.resolve()
@@ -438,8 +418,6 @@ export default function setupContext<T extends object>(
       return buildOwner(getApplication(), getResolver());
     })
     .then((owner) => {
-      associateDestroyableChild(context, owner);
-
       Object.defineProperty(context, 'owner', {
         configurable: true,
         enumerable: true,

addon/src/teardown-context.ts

@@ -1,5 +1,7 @@
 import type { TestContext } from './setup-context';
-import settled from './settled.ts';
+import Ember from 'ember';
+import { unsetContext } from './setup-context.ts';
+import settled, { _teardownAJAXHooks } from './settled.ts';
 import { _cleanupOnerror } from './setup-onerror.ts';
 import { destroy } from '@ember/destroyable';
 
@@ -30,7 +32,14 @@ export default function teardownContext(
     .then(() => {
       _cleanupOnerror(context);
 
-      destroy(context);
+      _teardownAJAXHooks();
+
+      // SAFETY: this is intimate API *designed* for us to override.
+      (Ember as any).testing = false;
+
+      unsetContext();
+
+      destroy(context.owner);
     })
     .finally(() => {
       if (waitForSettled) {

test-app/tests/unit/setup-application-context-test.js

@@ -257,4 +257,17 @@ module('setupApplicationContext', function (hooks) {
       'after click resolved',
     ]);
   });
+
+  test('can reset context during a test', async function (assert) {
+    await visit('/');
+    assert.equal(currentURL(), '/');
+
+    await teardownContext(this);
+    await setupContext(this);
+    await setupApplicationContext(this);
+    assert.equal(currentURL(), null);
+
+    await visit('/');
+    assert.equal(currentURL(), '/');
+  });
 });

test-app/tests/unit/setup-context-test.js

@@ -943,5 +943,19 @@ module('setupContext', function (hooks) {
         }
       }
     });
+
+    test('can reset context during a test', async function (assert) {
+      assert.expect(1);
+
+      let context = await setupContext({});
+      try {
+        await teardownContext(context);
+        context = await setupContext(context);
+      } finally {
+        await teardownContext(context);
+      }
+
+      assert.ok(true, 'No error calling setupContext after teardownContext');
+    });
   });
 });

test-app/tests/unit/teardown-context-test.js

@@ -65,28 +65,17 @@ module('teardownContext', function (hooks) {
     assert.strictEqual(getContext(), undefined, 'context is unset');
   });
 
-  test('destroyables registered with the context are invoked', async function (assert) {
-    registerDestructor(context, () => {
-      assert.step('destructor was ran');
-    });
-
-    assert.step('teardown started');
-
+  test('the owner is destroyed', async function (assert) {
     await teardownContext(context);
 
-    assert.step('teardown completed');
-
-    assert.verifySteps([
-      'teardown started',
-      'destructor was ran',
-      'teardown completed',
-    ]);
+    assert.ok(context.owner.isDestroyed);
   });
 
-  test('the owner is destroyed', async function (assert) {
+  test('the context is not destroyed', async function (assert) {
     await teardownContext(context);
 
     assert.ok(context.owner.isDestroyed);
+    assert.notOk(context.isDestroyed);
   });
 
   test('the application instance is destroyed and unwatched', async function (assert) {