test: add new tests for multiple examples

Added tests for CSS modules, Custom Documents and the Default Editor example

demos/src/Examples/CSSModules/React/index.spec.js

@@ -0,0 +1,11 @@
+context('/src/Examples/CSSModules/React/', () => {
+  before(() => {
+    cy.visit('/src/Examples/CSSModules/React/')
+  })
+
+  it('should apply a randomly generated class that adds padding and background color to the toolbar', () => {
+    cy.get('.toolbar').should('exist')
+    cy.get('.toolbar').should('have.css', 'background-color', 'rgb(255, 0, 0)')
+    cy.get('.toolbar').should('have.css', 'padding', '16px')
+  })
+})