test(TestScheduler): add failing test

spec/schedulers/TestScheduler-spec.ts

@@ -1,5 +1,6 @@
 import { expect } from 'chai';
 import { hot, cold, expectObservable, expectSubscriptions, time } from '../helpers/marble-testing';
+import { AsyncScheduler } from 'rxjs/internal/scheduler/AsyncScheduler';
 import { TestScheduler } from 'rxjs/testing';
 import { Observable, NEVER, EMPTY, Subject, of, concat, merge, Notification } from 'rxjs';
 import { delay, debounceTime, concatMap } from 'rxjs/operators';
@@ -441,5 +442,25 @@ describe('TestScheduler', () => {
  done();
  });
  });
+
+ it('should restore changes upon thrown errors', () => {
+ const testScheduler = new TestScheduler(assertDeepEquals);
+
+ const frameTimeFactor = TestScheduler['frameTimeFactor'];
+ const maxFrames = testScheduler.maxFrames;
+ const runMode = testScheduler['runMode'];
+ const delegate = AsyncScheduler.delegate;
+
+ try {
+ testScheduler.run(() => {
+ throw new Error('kaboom!');
+ });
+ } catch { /* empty */ }
+
+ expect(TestScheduler['frameTimeFactor']).to.equal(frameTimeFactor);
+ expect(testScheduler.maxFrames).to.equal(maxFrames);
+ expect(testScheduler['runMode']).to.equal(runMode);
+ expect(AsyncScheduler.delegate).to.equal(delegate);
+ });
  });
 });