Jest :TypeError: (intermediate value) is not iterable

Question

I have 2 methods below.

searchCertificates() is a private method which is called inside findAll().

   async findAll(queryCertificateDto: QueryCertificateDto): Promise<PaginatedResult> {
        const { data, meta } = await this.searchCertificates(queryCertificateDto);

        return {
            data,
            meta,
        };
    }

    private async searchCertificates(
        queryCertificateDto: QueryCertificateDto
    ): Promise<PaginatedResult> {
        const {
            page,
            take,
            certificateNo,      
            startDate,
            endDate,
        } = queryCertificateDto;
     

        const query = this.certificateRepository.createQueryBuilder('certificate');



        if (certificateNo) {
            query.andWhere('certificate.certificateNo=:certificateNo', { certificateNo });
        }
        if (startDate && endDate) {
            query.andWhere('CAST(certificate.createdAt as Date) BETWEEN :startDate AND :endDate', {
                startDate,
                endDate,
            });
        } else if (startDate) {
            query.andWhere('CAST(certificate.startDate as Date)=:startDate', { startDate });
        } else if (endDate) {
            query.andWhere('CAST(certificate.endDate as Date)=:endDate', { endDate });
        }

        const [certificates, total] = await query
            .orderBy('certificate.certificateNo', 'ASC')
            .take(take)
            .skip((page - 1) * take)
            .getManyAndCount();

        return {
            data: certificates,
            meta: {
                total,
                page,
                last_page: Math.ceil(total / take),
            },
        };
    }

I wrote below test case to cover startDate.

useValue: {
                        find: jest.fn().mockReturnValue(certificate),
                        createQueryBuilder: jest.fn(() => ({
                            andWhere: jest.fn().mockReturnValue(certificate),
                            getManyAndCount: jest.fn().mockReturnValueOnce(certificate),
                            orderBy: jest.fn().mockReturnThis(),
                            take: jest.fn().mockReturnThis(),
                            skip: jest.fn().mockReturnThis(),
                            page: jest.fn().mockReturnThis(),
                        })),
                        findOne: jest.fn().mockReturnValue(certificate),
                        save: jest.fn().mockReturnValue(new Certificate()),
                        softRemove: jest.fn().mockReturnValue(new Certificate()),
                    },

Below is the test case.

  it('return the Certificate list for start date', async () => {
        const queryCertificateDto = new QueryCertificateDto();
        queryCertificateDto.startDate = '23-MAR-2019';
        const result = await service.findAll(queryCertificateDto);
        expect(result['startDate']).toEqual(certificate.startDate);
    });

It is getting failing.

I don't know even the reason for it. Could you please help me to understand?

Answer 1

Your getManyAndCount mock should return a resolved value, and be mockResolvedValueOnce so that it can be awaited. It hsould also return an array of values, as you deconstruct the array into two parts, the certificates and the total