Alias in before block disappears after first test

[ashleymercer]

Current behavior

If we alias a value in a before() block then it can only be retrieved (with cy.get()) in the first test in a suite; attempting to retrieve it in the second or subsequent tests results in

cy.get() could not find a registered alias for: @alias.
You have not aliased anything yet.

Desired behavior

It is quite common to want to run a some initial query (e.g. a fetch from an API) at the start of a suite of tests, and alias with cy.as(). This alias should be available to all subsequent tests (within the current scope / context).

Test code to reproduce

describe(`Test`, () => {
  
  function fetchUsers() {
    return new Promise<string[]>(resolve => resolve(['Alice', 'Bob']))
  }

  before(() => {
    cy.wrap(fetchUsers()).as('users')
  })

  // This test passes...
  it(`test 1`, () => {
    cy.get('@users').should('have.length', 2)
  })

  // ...but this one fails
  it(`test 2`, () => {
    cy.get('@users').should('have.length', 2)
  })
})

Cypress Version

8.3.1

Other

One workaround is to move the setup steps to beforeEach but this might be heavyweight (e.g. running a bunch of initial API requests on every single test, rather than once per suite)

[ashleymercer]

I suspect this bug has the same root cause as #17467 but that issue was closed without being resolved, so this is still an issue in the latest versions.

[jennifer-shehane]

Duplicate of #665 Aliases can't be used in before blocks.