unit test error

[eduardo-r-web]

I defined the customer.service.ts resource and created its controller, but writing the unit tests I got the following error:

An error was thrown in afterAll TypeError: Cannot read property 'registerService' of undefined at CustomersService.register (http://localhost:9876/_karma_webpack_/webpack:/node_modules/ngx-jsonapi/__ivy_ngcc__/ngx-jsonapi/@ngx-jsonapi/ngx-jsonapi.js:2260:1) at http://localhost:9876/_karma_webpack_/webpack:/node_modules/ngx-jsonapi/__ivy_ngcc__/ngx-jsonapi/@ngx-jsonapi/ngx-jsonapi.js:2251:1 at timer (http://localhost:9876/_karma_webpack_/webpack:/node_modules/zone.js/dist/zone-evergreen.js:2561:1) at ZoneDelegate.invokeTask (http://localhost:9876/_karma_webpack_/webpack:/node_modules/zone.js/dist/zone-evergreen.js:406:1) at ProxyZoneSpec.push.QpwO.ProxyZoneSpec.onInvokeTask (http://localhost:9876/_karma_webpack_/webpack:/node_modules/zone.js/dist/zone-testing.js:332:1) at ZoneDelegate.invokeTask (http://localhost:9876/_karma_webpack_/webpack:/node_modules/zone.js/dist/zone-evergreen.js:405:1) at Zone.runTask (http://localhost:9876/_karma_webpack_/webpack:/node_modules/zone.js/dist/zone-evergreen.js:178:1) at invokeTask (http://localhost:9876/_karma_webpack_/webpack:/node_modules/zone.js/dist/zone-evergreen.js:487:1) at ZoneTask.invoke (http://localhost:9876/_karma_webpack_/webpack:/node_modules/zone.js/dist/zone-evergreen.js:476:1) at data.args. (http://localhost:9876/_karma_webpack_/webpack:/node_modules/zone.js/dist/zone-evergreen.js:2541:1)

How can i fix this?