无法覆盖 Angular 方法中的特定行

问：

我有这个类，我使用几个服务来获取数据，然后转换它并将其作为可观察的返回。无论我尝试什么，测试覆盖率都不仅仅涵盖其中的一个特定部分。尝试了各种不同的东西，但它没有覆盖。这是类：

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { Observable, Subject } from 'rxjs';
import { AccountDetail } from '../../models/accounts';
import { environment } from '../../../../environments/environment';
import { AccountDescriptionHelper } from '../../utils/account-subaccount';
import { GroupService } from '../group-structure';
import { TreeNode } from '../../models/treeNode';

@Injectable({
  providedIn: 'root'
})
export class AccountsChartService {
  private readonly ENDPOINT = `${environment}/ac`;

  constructor(
    private http: HttpClient,
    private groupService: GroupService,
    private accountDescriptionHelper: AccountDescriptionHelper
  ) {}

  loadAccountByChartService(bT: string, cT: string): Observable<Node[]> {
    const accountSubaccountDescEP = `${this.ENDPOINT}/cT/${cT}/ad`;
    let aCBS = new Subject<Node[]>();
    let aSAD = new Subject<AccountDetail[]>();
    this.http
      .get<AccountDetail[]>(accountSubaccountDescEP)
      .subscribe(response => {
        this.accountDescriptionHelper.storeMapFromDescriptionList(response);
        aSAD.next(response);
      });

      aSAD.subscribe(list => {
      this.groupService.getGroupedAccounts(cT, bT, list).subscribe(response => {
        aCBS.next(response);
      });
    });
    return aCBS.asObservable();
  }
}

以下是测试：

it('should be created', () => {
    expect(service).toBeTruthy();
  });

it('test', () => {
    httpClient = createHttpClient();

    service = new AccountsChartService(httpClient as HttpClient, groupService, asdHelper);
    const a = spyOn(groupService, 'getGroupedAccounts')
    const result = service.testMethod('1', 'Test');

    expect(result).toBeDefined();
    result.subscribe(() => {
      expect(a).toHaveBeenCalled();
    });
  });
});

它说这个特定的部分被发现，但我不知道我如何断言和操纵 aCBS 和 aSAD。我尝试将它们作为类实例变量移动，但同样的事情。只是不知道该怎么做。感谢您的观看。希望得到解决。

它说这部分是未覆盖的，其他一切都显示为覆盖：

list => {
      this.groupService.getGroupedAccounts(cT, bT, list).subscribe(response => {
        aCBS.next(response);
      });
    }