I Want to be able to write an integration test for this block of Code

I am trying to write an integration test for the body of code below, and i am actually new to writing test with JEST. Can i please get some help?...i am blocked on how to test the getClient() method and the authorize (session_variables) and other methods that are within the block of this code.

export default async (req: Request, res: Response) => {
  const client = getClient();
  try {
    const {
      event: { op, data, session_variables },
      table,
    } = req.body;
    // Authorize user
    authorize(session_variables);

    if (
      (op === 'INSERT' || op === 'UPDATE') &&
      (table.name === 'tickets' || table.name === 'tasks') &&
      table.schema === 'public'
    ) {
      const { new: newData } = data;

      if (table.name === 'tickets' && newData!.completedAt && newData!.code) {
        const groupDetail = await getGroup(newData!.code);
        if (groupDetail) {
          const id = groupDetail.id;
          const memberEmails = await getGroupMembers(id);
          await deleteGroup(id, memberEmails);
          return res.send(`error: false, messages: Group successfully deleted`);
        }
      } else if (
        op === 'UPDATE' &&
        newData!.completedAt &&
        newData!.ticketCode
      ) {
        const tasks = await fetchUncompletedTaskWithTicketCode(
          client,
          newData.ticketCode
        );

        if (tasks.length === 0) {
          const groupDetail = await getGroup(newData!.ticketCode);
          if (groupDetail) {
            const id = groupDetail.id;
            const memberEmails = await getGroupMembers(id);
            await deleteGroup(id, memberEmails);
            return res.send(
              `error: false, messages: Group successfully deleted`
            );
          }
        }
      }
    }
    return res.send(`error: true, message: event ignored`);
  } catch (error) {
    const err: Error = error;
    Sentry.captureException(err);
    return res.send(`err: true, message: ${err}`);
  }
};

i am expected the write an integration test for this method above.