Refactor examples to encapsulate login flow

Author: debrisapron

content/guides/end-to-end-testing/auth0-authentication.md

@@ -144,19 +144,11 @@ Next, we'll write a custom command called `loginToAuth0` to perform a login to
 ```js
 // cypress/support/auth-provider-commands/auth0.ts
 
-Cypress.Commands.add('loginToAuth0', (username: string, password: string) => {
-  const log = Cypress.log({
-    displayName: 'AUTH0 LOGIN',
-    message: [`🔐 Authenticating | ${username}`],
-    // @ts-ignore
-    autoEnd: false,
-  })
-  log.snapshot('before')
-
+function loginViaAuth0Ui(username: string, password: string) {
   // App landing page redirects to Auth0.
   cy.visit('/')
 
-  // Login on Auth0 (we'll add caching later).
+  // Login on Auth0.
   cy.origin(
     Cypress.env('auth0_domain'),
     { args: { username, password } },
@@ -169,6 +161,18 @@ Cypress.Commands.add('loginToAuth0', (username: string, password: string) => {
 
   // Ensure Auth0 has redirected us back to the RWA.
   cy.url().should('equal', 'http://localhost:3000/')
+}
+
+Cypress.Commands.add('loginToAuth0', (username: string, password: string) => {
+  const log = Cypress.log({
+    displayName: 'AUTH0 LOGIN',
+    message: [`🔐 Authenticating | ${username}`],
+    // @ts-ignore
+    autoEnd: false,
+  })
+  log.snapshot('before')
+
+  loginViaAuth0Ui(username, password)
 
   log.snapshot('after')
   log.end()
@@ -221,26 +225,10 @@ Cypress.Commands.add('loginToAuth0', (username: string, password: string) => {
   })
   log.snapshot('before')
 
-  const args = { username, password }
   cy.session(
     `auth0-${username}`,
     () => {
-      // App landing page redirects to Auth0.
-      cy.visit('/')
-
-      // Login on Auth0.
-      cy.origin(
-        Cypress.env('auth0_domain'),
-        { args },
-        ({ username, password }) => {
-          cy.get('input#username').type(username)
-          cy.get('input#password').type(password, { log: false })
-          cy.contains('button[value=default]', 'Continue').click()
-        }
-      )
-
-      // Ensure Auth0 has redirected us back to the RWA.
-      cy.url().should('equal', 'http://localhost:3000/')
+      loginViaAuth0Ui(username, password)
     },
     {
       validate: () => {