How to use onClickOverlay method in Cypress

Your question is a bit confusing, you say 5 test cases in single suite file but your example cypress run --spec 'cypress/integration/TestCase2.js implies individual spec files.

I'll give you an answer both ways.

Individual spec files

Please see the third example docs - cypress run --spec which runs two tests, comma separated.

cypress run --spec "cypress/integration/TestCase2.spec.js,cypress/integration/TestCase5.spec.js"

Single suite file

Please see How to add test case grouping in Cypress which uses a beforeEach() to check test names passed in by ENV variable.

Add this at the top of your single test suite

beforeEach(function() {

  const testFilter = Cypress.env('TEST_FILTER');
  if (!testFilter) return;                       // exit if no filter defined

  const testName = Cypress.mocha.getRunner().test.fullTitle();
  if (!testFilter.includes(testName)) {
    this.skip();
  }
})

Run with

set CYPRESS_TEST_FILTER=Test2;Test5 & cypress open

or

cypress open --env TEST_FILTER=Test2;Test5  

Note when using the --env flag, the test names must not be separated by a comma since Cypress uses that internally to delimit multiple ENV variables.

Thank you for the help everyone! With your suggestions, I was able to translate what I needed to write in Cypress.io to make this idea work and it came down to writing this inside of the commands.js file in the support directory:

Cypress.Commands.add('getDataE2EID', function (id) {
  return cy.get(`[data-e2e="${id}"]`)
})

cy.getDataE2EID('first-div-element') <--- will get me the first div

Now, I can have a custom cypress function that allows me to pass in whatever value I want where the key is 'data-e2e'.

Create your array of invoices first, then embed it in your data structure ...

const tokenValue = "000";
let invoiceIds = [1, 2, 3];
let amounts = [10, 20, 30];

// Create invoices array first
const invoices = [];
for (let i = 0; i < invoiceIds.length; i++) {
  invoices.push({invoiceId: invoiceIds[i], amount: amounts[i]});
}

// ...then build data structure
const data = {token: tokenValue, invoices};

// Then save to file (or just log, as we're doing here)
console.log('invoice.json', data);

Well this seems to work, so it tells me I have some more to learn about .should()

cy.get('.check-box-sub-text').should('not.exist');

Adding headers to a cy.visit() request was added in 3.2.0. Update your installed Cypress version and try that again.

Here's a screenshot of the code from the OP running in Cypress 3.2.0:

You could do something like this

Cypress.Commands.add(
  'selectNth',
  { prevSubject: 'element' },
  (subject, pos) => {
    cy.wrap(subject)
      .children('option')
      .eq(pos)
      .then(e => {
        cy.wrap(subject).select(e.val())
      })
  }
)

Usage

cy.get('[name=assignedTo]').selectNth(2)

From the question and the comments above, it sounds like you're trying to do something like this:

1. set up your application
2. click a button (or do something else) to start a request to an API
3. capture the response from the API
4. use the response to test something else in your application (perhaps make sure some text changes on the page?)

While it is possible to write tests in this way, there is a problem with this: the response from the API may change depending on circumstances outside your control. For example, what happens if you're working on your project and the API happens to be down that day? Your code is going to break and it won't be due to a bug in your code. In fact, you won't be testing your code at all (at least not the code you thought you were testing), because you won't be getting the response you want from the API.

This is why Cypress provides a way to stub the requests - to make sure that when your tests are running, you are getting the response you want from the API. If you want to write a test to see what happens when the API returns value A, you need to make sure the API doesn't return value B. Stubbing the requests allows you to make sure the application gets value A when you need it to.

So the examples you've seen probably do something like this:

1. set up your application
2. use cy.route to stub the API requests to return a known value
3. click the button - your app now makes a request and gets back that known value
4. test your application to make sure it does what you expect when it gets that known value.

If you have a range of different response values for which you want to test your app's behaviour, write a set of tests, one for each value.

The main difference is conceptual, but there are some practical considerations as well.

Fixtures are meant for files that are used only for your tests, e.g. placeholder test data, sample responses and so forth. In other terms, fixtures are files that would not be a part of your project if you didn't have tests.

For this end, fixtures provide some convenience utilities, such as piping them directly into cy.route():

cy.route('GET', '/users', 'fixture:users');

readFile() on the other hand is a generic method that you can use to read more or less anything. It is a good candidate if you need to read files that are a part of your regular project code, e.g. translations:

cy.readFile('translations/en_US.json').then(...);

What you're doing makes complete sense, but simply put, you cannot. (per the docs). https://docs.cypress.io/guides/core-concepts/variables-and-aliases/#Return-Values

You can, however, use aliases to accomplish what (I think) you're after.
https://docs.cypress.io/guides/core-concepts/variables-and-aliases/#Aliases