Angular Jest测试：节点：10672UnhandledPromiseRejectionWarning：TypeError：将圆形结构转换为JSON

如何解决Angular Jest测试：节点：10672UnhandledPromiseRejectionWarning：TypeError：将圆形结构转换为JSON

在运行有角度的开玩笑的测试用例时，各个材料组件都面对圆形结构下方的JSON问题

(node:10672) UnhandledPromiseRejectionWarning: TypeError: Converting circular structure to JSON
        --> starting at object with constructor 'Object'
        |     property 'element' -> object with constructor 'Object'
        |     property 'componentProvider' -> object with constructor 'Object'
        --- property 'parent' closes the circle
        at stringify (<anonymous>)
        at writeChannelMessage (internal/child_process/serialization.js:117:20)
        at process.target._send (internal/child_process.js:779:17)
        at process.target.send (internal/child_process.js:677:19)
        at reportSuccess (D:\Lam\develop\law\node_modules\jest-worker\build\workers\processChild.js:67:11)