Add failing test case for autotracking of derived state

tests/integration/misc-test.js

@@ -0,0 +1,62 @@
+import { module, test } from 'qunit';
+import { setupRenderingTest } from 'ember-qunit';
+import { get, set } from '@ember/object';
+import { Changeset } from 'ember-changeset';
+import hbs from 'htmlbars-inline-precompile';
+import { render, find, settled } from '@ember/test-helpers';
+
+module('Integration | misc', function(hooks) {
+  setupRenderingTest(hooks);
+
+  test('it re-renders derived state automatically when root state changes', async function(assert) {
+    class MyModel {
+      isOptionOne = false;
+      isOptionTwo = false;
+      isOptionThree = false;
+    }
+
+    const Validations = {
+      isOptionSelected: (newValue) => {
+        return newValue === true ? true : 'No options selected';
+      }
+    }
+
+    function myValidator({ key, newValue, oldValue, changes, content }) {
+      let validatorFn = get(Validations, key);
+
+      if (typeof validatorFn === 'function') {
+        return validatorFn(newValue, oldValue, changes, content);
+      }
+    }
+
+    const myObject = new MyModel();
+    const myChangeset = Changeset(myObject, myValidator, Validations);
+
+    Object.defineProperty(myChangeset, 'isOptionSelected', {
+      get() {
+        return this.get('isOptionOne') || this.get('isOptionTwo') || this.get('isOptionThree');
+      }
+    });
+
+    // initial validation
+    await myChangeset.validate();
+
+    this.set('myChangeset', myChangeset);
+
+    await render(hbs`
+      {{#if this.myChangeset.isInvalid}}
+        <span class="invalid"></span>
+      {{else}}
+        <span class="valid"></span>
+      {{/if}}
+    `);
+
+    assert.ok(find('.invalid'), 'Changeset is invalid as none of the options are selected');
+
+    set(myChangeset, 'isOptionTwo', true);
+    await settled();
+
+    // We don't call validate explicitly, expecting autotracking to handle that since skipValidate is false
+    assert.ok(find('.valid'), 'Changeset is valid as one of the options is selected');
+  });
+});