Question

我正在使用node.js开发一个nestjs应用程序我有一个名为LoggerService的类，如下所示：

export class LoggerService {

    private logger: Rollbar;

    constructor() {
        this.logger = this.setupLogger();
    }

    critical(...args: Array<string | Error | object | Date | any[]>) {
        this.logger.error(...args);
    }

    private setupLogger(): Rollbar {
        if (this.logger == null) {

            this.logger = new Rollbar({
                accessToken: 'token',
                environment: 'dev',
                captureUncaught: true,
                captureUnhandledRejections: true,
            });

        }

        return this.logger;
    }

现在，我正在使用下面的玩笑为此类编写单元测试。

describe('LoggerService.log', () => {
  let service: LoggerService;

  beforeEach(async () => {

    const module: TestingModule = await Test.createTestingModule({
      providers: [LoggerService],
    }).compile();

    service = module.get<LoggerService>(LoggerService);
  });

  it('critical', () => {
    service.critical('error','message');
    expect(???).toHaveBeenCalledWith('error', 'message')
  })

);

我的问题是如何检查（期望）是否调用logger.error，或如何在此类中模拟Rollbar。

Answer 1

1）提供您的外部依赖关系/库作为模块中的可注入令牌

from typing import Dict, List, TextIO

def read_grades(gradefile: TextIO) -> Dict[float, List[str]]:
    """Read the grades from gradefile and return a dictionary where each key is a grade and each value is the list of ids of students who earned that grade.

    Precondition: gradefile starts with a header that contains no blank lines, then has a blank line, and then lines containing s dtudent number and a grade.
    """
    # skip over the header

    line = gradefile.readline()
    while line != 'n/':
        line = gradefile.readline()

    # read the grades, accumulating them into a dict
    grade_to_ids = {}

    line = gradefile.readline()

    while line != '':
        student_id = line[:4]
        grade = float(line[4:].strip())

        if grade not in grade_to_ids:
            grade_to_ids[grade] = [student_id]
        else:
            grade_to_ids[grade].append(student_id)

        line = gradefile.readline()

    return grades_to_ids

2）将其注入您的@Module({ providers: [ { provide: 'Rollbar', useFactory: async (configService: ConfigService) => new Rollbar({ accessToken: configService.accessToken, environment: configService.environment, captureUncaught: true, captureUnhandledRejections: true, }), inject: [ConfigService], }, ]中，而不是创建它

LoggerService

3）现在，您可以在测试中模拟依赖项

export class LoggerService {
    constructor(@Inject('Rollbar') private logger: Rollbar) {
    }

如何使用玩笑嘲笑第三方库

1 个答案: