Explain how cy.fixture() works and when to use it vs cy.intercept stubbing.

cy.fixture(filename) reads from cypress/fixtures/, returning the parsed contents (JSON parsed, others as text). It's a Cypress command, so it's queued — chain with .then to use the result.

The two primary uses:

As a payload for cy.intercept:

cy.intercept('GET', '/api/cart', { fixture: 'cart-with-3-items.json' });

Cypress reads the fixture and uses it as the response body. This is the cleanest way to stub a stable response shape — the fixture file is checked into git, named, and reused across tests.

As an input value:

cy.fixture('users').then((users) => {
  cy.get('[data-test=email]').type(users[0].email);
});

When to prefer fixtures:

• Response is static and shared across multiple tests.
• The data is non-trivial (50+ lines of JSON).
• You want non-engineers (e.g., PMs, product designers) to read it.

When to prefer inline cy.intercept bodies:

• One-off response, used in a single test.
• The body needs to be computed at test time (timestamps, IDs).
• You want the assertion data and the stub data side-by-side in the spec for readability.

A common hybrid: load a fixture, modify it for the specific test:

cy.fixture('cart').then((cart) => {
  cart.total = 99.99;
  cy.intercept('GET', '/api/cart', cart);
});