When asserting that an element is found is using .exists necessary?

Question

It seems that,

t.expect(Selector("[data-testid='foo']")).ok();

and,

t.expect(Selector("[data-testid='foo']").exists).ok();

result in the same outcome so is .exists necessary?

Answer 1

Selector("[data-testid='foo']") returns a Promise. The t.expect(Selector("[data-testid='foo']")).ok(); assertion will always pass regardless of whether there is an element on the page or not. It happens because a Promise instance will be cast to true.  

t.expect(Selector("[data-testid='foo']").exists).ok(); is the correct assertion. It checks an element on the page using the Smart assertion query mechanism