fix: return raw fixture when encoding is specified

[adamalston]

• Closes fixture with base64 encoding returns an object instead of a string #32139

Additional details

I'm not sure if an end-to-end test should also be added. This one worked when I added it in packages/driver/cypress/e2e/commands/fixtures.cy.js:

it('should return encoded JSON', () => {
  const fixture = 'example'
  const fixtures = [
    { fixture, encoding: undefined, content: { example: true } },
    // TODO: Use the same file in all `fixture` calls after
    // https://github.com/cypress-io/cypress/issues/32138 is addressed.
    { fixture: 'app', encoding: 'base64', content: 'ewogICJzb21lIjogImpzb24iLAogICJmb28iOiB7CiAgICAiYmFyIjogImJheiIKICB9Cn0K' },
    // TODO: Use the same file in all `fixture` calls after
    // https://github.com/cypress-io/cypress/issues/32138 is addressed.
    { fixture: 'valid', encoding: 'utf8', content: '{\n  "foo": 1,\n  "bar": {\n    "baz": "cypress"\n  }\n}\n' },
    // TODO: Use the same file in all `fixture` calls after
    // https://github.com/cypress-io/cypress/issues/32138 is addressed.
    { fixture: 'null.json', encoding: '', content: 'bnVsbAo=' },
  ]

  fixtures.forEach(({ fixture, encoding, content }) => {
    cy.fixture(fixture, encoding).should('deep.equal', content)
  })
})

Steps to test

cd packages/server
yarn test-watch test/unit/fixture_spec.js # tests should pass
git checkout develop packages/server/lib/fixture.js # tests should fail

How has the user experience changed?

N/A

PR Tasks

• Have tests been added/updated?
• Has a PR for user-facing changes been opened in cypress-documentation?
• Have API changes been updated in the type definitions?

[cypress-app-bot]

• Create a Draft Pull Request if your PR is not ready for review. Mark the PR as Ready for Review when you're ready for a Cypress team member to review the PR.

[adamalston]

Hmm, the throws when json is invalid test fails locally without the changes in f9350b7 but it fails in CI with them.

[AtofStryker]

@adamalston a unit test should be all that is necessary here since the e2e test would essentially be testing the same functionality that we care about. My only concern is that this could possibly be disruptive, but I can't think of a case that would be problematic off the top of my head. Either way this will be making it's way into Cypress 15.

Thank you for the contribution!