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Assertions

device.expect(selector, options?) returns an assertion object. Every assertion is async, retries until it passes or the timeout elapses, and supports .not.

await device.expect('cart-badge').toHaveText('1');
await device.expect('cart-badge', { waitTimeout: 10000 }).toHaveText('1');
await device.expect('spinner').not.toBeVisible();

toContain(text)​

Passes when the element's text content contains text.

await device.expect('welcome-banner').toContain('Emily');

toHaveText(text)​

Passes when the element's trimmed text content equals text exactly.

await device.expect('cart-qty-1-value').toHaveText('2');

toBeVisible()​

Passes when the element is in the DOM and visible (not display: none or visibility: hidden).

.not.toBeVisible() passes when the element is hidden or absent — and waits for it to become so.

await device.expect('modal').toBeVisible();
await device.expect('spinner').not.toBeVisible(); // waits for the spinner to go away

toExist()​

Passes when the element is present in the DOM, visible or not.

.not.toExist() passes when the element is absent — and waits for it to be removed.

await device.expect('cart-line-1').toExist();
await device.click('cart-remove-1');
await device.expect('cart-line-1').not.toExist(); // waits for removal

toHaveValue(value)​

Passes when the input's value equals value.

await device.expect('email-input').toHaveValue('user@example.com');

toHaveAttribute(name, value)​

Passes when the element's attribute name equals value.

await device.expect('nav-link-home').toHaveAttribute('data-active', 'true');

toHaveClass(className)​

Passes when the element's class list contains className.

await device.expect('alert').toHaveClass('alert-error');

toHaveCount(count)​

Passes when the number of elements matching the selector equals count. Polls the count directly, so toHaveCount(0) works even if the element never existed.

await device.expect('[data-testid^="dish-card-"]').toHaveCount(12);
await device.expect('error-message').toHaveCount(0);

Failure output​

Failed assertions throw with expected/actual values and the page URL:

Assertion "toHaveText" failed for "cart-badge" (resolved to "[data-testid="cart-badge"]")
  Expected: to equal "2"
  Actual: 1
  Page URL: https://your-app.com/cart