add spec to spy on random number

Author: bahmutov

examples/webpack-options/cypress/component/ChildComponent.cy-spec.js

@@ -0,0 +1,20 @@
+/// <reference types="cypress" />
+import React from 'react'
+import { mount } from 'cypress-react-unit-test'
+import ChildComponent from './ChildComponent'
+import * as calc from './calc'
+
+describe('ChildComponent unstubbed', () => {
+  it('works', () => {
+    cy.spy(calc, 'getRandomNumber').as('getRandomNumber')
+    mount(<ChildComponent />)
+    // make sure the component shows the random value
+    // returned by the calc.getRandomNumber function
+    cy.get('@getRandomNumber')
+      .should('have.been.called')
+      .its('returnValues.0')
+      .then(n => {
+        cy.contains('.random', n)
+      })
+  })
+})