How can you attach a file and send JSON data into a request body using supertest?

I have an endpoint I am testing with Jest and Supertest.

  '/',
  [
    requiresAuthentication(),
    upload.fields([
      { name: 'background', maxCount: 1 },
      { name: 'logo', maxCount: 1 },
      { name: 'additionalResources', maxCount: 1 },
    ]),
    body('name').isString().isLength({ min: 0, max: 255 }).exists(),
    body('badgeIssuer').isString().isLength({ min: 0, max: 255 }).exists(),
    body('badgeName').isString().isLength({ min: 0, max: 255 }).exists(),
    body('headerColor').isString().isLength({ min: 0, max: 255 }).exists(),
    body('bodyTextColor').isString().isLength({ min: 0, max: 255 }).exists(),
    body('buttonBGColor').isString().isLength({ min: 0, max: 255 }).exists(),
    body('buttonTextColor').isString().isLength({ min: 0, max: 255 }).exists(),
    body('thankYouMessage').isString().isLength({ min: 0, max: 1024 }).exists(),
  ],
  async (req: any, res: Response) => {
    const errors = validationResult(req);

    if (!errors.isEmpty() || !req.admin) {
      return res.status(400).json({ errors: errors.array() });
    }

    const background =
      req.files.background !== undefined ? req.files.background[0] : null;
    const logo = req.files.logo !== undefined ? req.files.logo[0] : null;
    const additionalResources =
      req.files.additionalResources !== undefined
        ? req.files.additionalResources[0]
        : null;

    if (logo === null)
      return res
        .status(400)
        .json({ errors: [{ msg: 'Logo is not provided' }] });

    try {
      if (Array.isArray(req.files)) throw new Error('Invalid uploads');

      const {
        name,
        badgeIssuer,
        badgeName,
        headerColor,
        bodyTextColor,
        buttonBGColor,
        buttonTextColor,
        thankYouMessage,
      }: Campaign = req.body;
      const createCampaign = await prisma.campaign.create({
        data: {
          name,
          background: background === null ? null : formatFile(background),
          logo: formatFile(logo),
          headerColor,
          bodyTextColor,
          buttonTextColor,
          buttonBGColor,
          badgeIssuer,
          badgeName,
          postcodeQuestion: 1,
          thermometerQuestion: 'West Midlands',
          wordcloudQuestion: 2,
          additionalResources:
            additionalResources === null
              ? null
              : formatFile(additionalResources),
          thankYouMessage,
          editURL: '',
          publicURL: '',
          sheetId: '',
          open: true,
          createdAt: new Date(),
        },
      });

      try {
        const {
          response: {
            result: { editURL, publicURL, ssID: spreadsheetID },
          },
        } = await makeAGoogleForm(name, createCampaign.id.toString());

        const updatedCampaign = await prisma.campaign.update({
          where: { id: createCampaign.id },
          data: {
            editURL,
            publicURL,
            sheetId: spreadsheetID,
          },
        });

        return res.json({
          updatedCampaign,
        });
      } catch (err) {
        await prisma.campaign.delete({
          where: { id: createCampaign.id },
        });
      }
    } catch (err) {
      res.status(400).json({ errors: [{ msg: (err as Error).message }] });
    }
  }
);

In order to test it I am required to send a file and send json data, but .send and .attach do not work at the same time. Is there a work around this, or do I need to refactor the end point and test services separately? Just to be clear, I did not write the code here I am only testing it.