In Cypress how to count a selection of items and get the length?

Question

I'm starting to learn Cypress. I have a 4 row table (with a class of datatable). I can verify the number of rows this way:

cy.get('.datatable').find('tr').each(function(row, i){
        expect(i).to.be.lessThan(4)
})

This is fine, but it seems awkward, since I just want to count the length and don't really need to access the stuff in the rows, and I assume it's faster to do one thing than do 4 things.

If I log the selection (not sure what else to call it):

cy.log(cy.get('.datatable').find('tr'))

it comes out as [object Object] and I'm not quite sure how to deconstruct that, which suggests to me that I'm thinking about this all wrong.

If I try:

expect(cy.get('.datatable').find('tr')).to.have.lengthOf(4)

I get AssertionError: expected { Object (chainerId, firstCall) } to have a property 'length'

If I try:

    expect(Cypress.$('.datatable > tr')).to.have.lengthOf(4)

I get AssertionError: expected { Object (length, prevObject, ...) } to have a length of 4 but got 0 so at least it has a length here?

If I log that method of selection I get Object{4}. I'm not sure where to go from here. It seems like this would be a very common thing to deal with.

Answer 1

Found a solution, This works to check a count of items:

cy.get('.datatable').find('tr').should('have.length', 4)

This does not work with the Cypress.$() method of notation.

Reference: https://docs.cypress.io/guides/references/assertions.html#Length

Answer 2

You can also get the length of a selection of items through its property, for example:

cy.get('.datatable').find('tr').its('length').should('eq', 4)
cy.get('.datatable').find('tr').its('length').should('be.gte', 4)

In addition to should('have.length', 4)

I tested with Cypress version 3.1.0 and 3.2.0.

Answer 3

From the cypress API docs .should() section, using an arrow function:

cy.get('.datatable').find('tr').should(($listOfElements) => {
   expect($listOfElements).to.have.length(4)
   // any other assertions, for example the below one
   // expect($listOfElements).to.have.any.keys('key1', 'key2')
})

This approach will allow you to use Chai BDD notation and assert more than one thing on your list of elements.

Answer 4

if you want more flexible and have a dynamic result use this.

cy.get('.listings-grid')
  .find('.listing')
  .then(listing => {
    const listingCount = Cypress.$(listing).length;
    expect(listing).to.have.length(listingCount);
  });

Answer 5

One option is to use "have.length" ...

cy.get('.datatable tr').should('have.length', 4)

...another option is to use should

cy.get('.datatable tr').should(($tr) => {
    expect($tr).to.have.length(4)
})

...or then (synchronous queries)

cy.get('.datatable').then(($table) => {
  // synchronously query to find length of elements
  expect($table.find('td').length).to.equal(4)
})