我知道下面的错误
An error was thrown in afterAll
TypeError: this.router.navigate(...) is undefined in http://localhost:9876/_karma_webpack_/main.js (line 6552)
59104/signOut/<@http://localhost:9876/_karma_webpack_/main.js:6552:25
__tryOrUnsub@http://localhost:9876/_karma_webpack_/vendor.js:161782