install cypress and add initial test

cypress/support/e2e.ts

@@ -0,0 +1,5 @@
+/// <reference types="cypress" />
+
+Cypress.Commands.add('dataCy', value => {
+  return cy.get(`[data-cy=${value}]`);
+});

cypress/support/index.d.ts

@@ -0,0 +1,11 @@
+/// <reference types="cypress" />
+
+declare namespace Cypress {
+  interface Chainable {
+    /**
+     * Custom command to select DOM element by data-cy attribute.
+     * @example cy.dataCy('greeting')
+     */
+    dataCy(value: string): Chainable<JQuery<HTMLElement>>;
+  }
+}