Test Runner and Commands

Treat it as a short migration crutch, not a setting. It is deprecated and scheduled for removal, so use it to keep named specs green through one upgrade while you rewrite the assertions that depended on ancestor clipping.

Cypress's .trigger() dispatches the named event and nothing else: no default browser action, no companion events, no focus change. Use it where the behaviour under test really is a listener, and keep real action commands wherever the browser default is the point.

Only as far as the chain naturally goes. Treat deep callback nesting as a signal that the spec is discovering what it should already know, and move that knowledge into seeded data or a retried assertion.

Share setup only when the value is read-only for the whole file, expensive to produce, and identical for every test. Anything a test can mutate stays per test, because a shared mutable value makes the suite order-dependent and unreproducible locally.

Only for a small, read-only block where page loads dominate and no test mutates state another reads, approved on the condition that every test in it still passes under .only. Never at the root config.

Only helpers that are a pure, synchronous, repeatable read of the page or browser state. Anything that acts, awaits, or drives other cy commands must be a command — and a command stops the chain relinking after it.

It measures rather than listens. On each retry Cypress records the element's position and compares the last two samples; if they are more than animationDistanceThreshold apart, five pixels by default, the element counts as animating.

Cypress fires at a coordinate, not at a node. The click lands on whatever element is topmost at that point, so a child covering the button's centre gets the event, and the Command Log names it. Focus still goes to the button.

Nothing replaces it. cy.end() ended a chain by yielding null, which was never needed, because a Cypress chain is already terminated as soon as the next cy command starts a new one. In Cypress 16 you simply delete the calls.

A static alias stores the resolved value once, at the moment .as() runs, instead of the query chain that produced it. cy.get('@total') then returns that frozen value on every read rather than re-deriving it from the page.

Because the browser-context reset happens at the boundary between tests, not inside one. Cypress resolves it per suite, so a per-test value would be ambiguous, and it errors that testIsolation can only be overridden from a suite-level override.

Because the loop never gives control back. Cypress only starts running commands once the spec body finishes, so every iteration piles more commands onto the queue, the exit condition can never flip, and the browser eventually gives out.

Cypress's .each() always yields back the array-like subject it was given, whatever the callback returns, and it deliberately breaks the subject link to any chain the callback started. Only returning exactly false means something: it ends the loop early.

Almost never for anything that changes what is asserted. Branching on the attempt number makes the retry a different test, so a green second attempt no longer tells you the first failure was environmental. Extra diagnostics are the defensible exception.