test: added custom header E2E test

Author: nickytonline

cypress/integration/default/custom-headers.spec.ts

@@ -0,0 +1,7 @@
+describe('custom headers', () => {
+  it('should load custom headers', () => {
+    cy.request('/').then((request) => {
+      cy.wrap(request.headers['x-custom-header']).should('equal', 'my custom header value')
+    })
+  })
+})