How to add test case grouping in Cypress

You can dynamically skip a test by using this.skip(), which can be applied conditionally based on, say, an environment variable.

To do it globally add a beforeEach() into cypress/suport.index.js.

beforeEach(function() {

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

Note, you must use a function() not an arrow function.

The variable testName includes the text from nested context(), describe(), and it(), for example, in the sample assertions.spec.js provided by Cypress

This

context('Assertions', () => {
  beforeEach(() => {
    cy.visit('https://example.cypress.io/commands/assertions')
  })

  describe('Implicit Assertions', () => {
    it('.should() - make an assertion about the current subject', () => {

has a testName of

"Assertions Implicit Assertions .should() - make an assertion about the current subject"

In package.json

  "scripts": {
    "cy:open": "cypress open",
    "cy:filter:implicit": "set CYPRESS_TEST_FILTER=Implicit & cypress open"
  },

Note the CYPRESS_ prefix, but in the code it's just TEST_FILTER.

Then,

yarn cy:filter:implicit

will skip all the "Explicit Assertions" tests.