I am new in testing in my project i want to test call API i have been test get call API but i have no idea how to test POST call what i did for testing get call like this in my folder mocks in file firebase.js:

export default {
  get: () => {
    return Promise.resolve({
      data: [{
        "id": "qcCK3SzECmaZAGRrHjaC",
        "status": "refused",
        "pct": 20,
        "amount": 200,
        "email": "a@a",
        "name": "test2",
        "vat": "40",
        "fileName": "preview-facture-free-201801-pdf-1.jpg",
        "date": "2002-02-02",
        "commentAdmin": "pas la bonne facture",
        "commentary": "test2",
        "type": "Restaurants et bars",
        "fileUrl": "https://firebasestorage.googleapis.com/v0/b/billable-677b6.a…f-1.jpg?alt=media&token=4df6ed2c-12c8-42a2-b013-346c1346f732"
      }]
    })
  },
}

in the folder tests :

import firebase from "../__mocks__/firebase"
import BillsUI from "../views/BillsUI.js"
    describe("Given I am connected as Employee",()=>{
      describe("When I navigate to bills page",()=>{
        test("fetches bills from mock API GET", async () => {
          const getSpy = jest.spyOn(firebase, "get")
          const bills = await firebase.get()
          expect(getSpy).toHaveBeenCalledTimes(1)
          expect(bills.data.length).toBe(1)
       })
       test("fetches bills from an API and fails with 404 message error", async () => {
        firebase.get.mockImplementationOnce(() =>
          Promise.reject(new Error("Erreur 404"))
        )
        const html = BillsUI({ error: "Erreur 404" })
        document.body.innerHTML = html
        const message = await screen.getByText(/Erreur 404/)
        expect(message).toBeTruthy()
      })
      test("fetches messages from an API and fails with 500 message error", async () => {
        firebase.get.mockImplementationOnce(() =>
          Promise.reject(new Error("Erreur 500"))
        )
        const html = BillsUI({ error: "Erreur 500" })
        document.body.innerHTML = html
        const message = await screen.getByText(/Erreur 500/)
        expect(message).toBeTruthy()
      })
      })
    })

this how Mocking API get and testing any idea how to mock call API POST ?