Just a simple Firebase cleanup script to delete a given user by eMail address before a cypress test runs.

firebase-cypress.js

// signup.spec.js

/// <reference types="cypress" />

const path = require('path')

describe('Testing the user system', () => {
    let user

    beforeEach(() => {
        cy.visit('http://localhost:3000/login')
        cy.fixture('user.json').then((u) => (user = u))
    })

    it('successfully signs up', () => {
        console.log(user)
        cy.exec('node ./cypress/cleanupFirebase.js', {
            env: { email: user.email },
        }).then((result) => {
            console.log(result.code)
            console.log(result.stderr)
            console.log(result.stdout)
        })
        /**
         * cy.exec(command, options)
         * Actived login via eMail and enter a username, eMail address and password.
         */
        cy.get('div').contains('Ich habe noch keinen Account').click()
        cy.get('input[name=name]').type(user.name)
        cy.get('input[name=email]').type(user.email)
        cy.get('input[name=password]').type(user.password)
        cy.get('form').submit()

        /**
         * The communication wizard should start.
         * Select eMail.
         */
        cy.url().should('include', '/welcome')
        cy.get('div').contains('E-Mail').click()

        /**
         * The eMail input should be filled with the allready provided eMail address
         */
        cy.get('input[name=email]').should('have.value', user.email)
        cy.get('form').submit()
    })
})

// cleanupFirebase.js 
var admin = require('firebase-admin')
var app = admin.initializeApp()

if (!process.env.email) console.log('no email provided')

admin
    .auth()
    .getUserByEmail(process.env.email)
    .then(function (userRecord) {
        // See the UserRecord reference doc for the contents of userRecord.
        // console.log('Successfully fetched user data:', userRecord.toJSON())
        admin
            .auth()
            .deleteUser(userRecord.uid)
            .then(function () {
                console.log('Successfully deleted user')
                process.exit(0)
            })
            .catch(function (error) {

                console.log(error.code)
                process.exit(1)
            })
    })
    .catch(function (error) {
        if (error.code === 'auth/user-not-found') process.exit(0)
        console.log('Error fetching user data:', error)
        process.exit(1)
    })