cy.intercept() network capture timing during before() hooks

Answer

When cy.intercept() is placed in a before() hook, Cypress registers the intercept synchronously before any it() block runs. Cypress also delays processing of the page load until after all before() hooks finish, so the intercept is active for the very first network request triggered by the initial cy.visit().

Confirmed facts

• Registration of cy.intercept() in before() occurs before the test runner starts the it() block.
• Cypress buffers the page load and waits for before() hooks to complete before letting the browser navigate, preventing a race where an inline script could run before the intercept is attached.
• All network traffic is proxied through Cypress, so any request that leaves the browser (including early AJAX, fetch, or XHR) is subject to the intercepts that are already registered.
• Moving the identical intercept to an it() block placed before cy.visit() yields the same capture behavior.

Steps to verify interception of the first request

1. Define the intercept with an alias in a before() hook:

before(() => {
  cy.intercept('GET', '/api/config').as('getConfig');
});

2. Visit the application:

it('loads page and stubs config', () => {
  cy.visit('/');
});

3. Wait for the aliased request to confirm it was intercepted:

cy.wait('@getConfig').its('response.statusCode').should('eq', 200);

Alternative verification approaches

• Log timestamps: add console.log('intercept registered', Date.now()) inside the before() hook and console.log('request intercepted', Date.now()) in the intercept’s request handler; the request timestamp should be later.
• Run the test with cypress open --debug and inspect the Command Log; the network request will appear under the intercept entry.
• Repeat the test with the intercept moved into the it() block before cy.visit(); the capture result should be identical, confirming that before() registration is early enough.