seed sibling node in layout test

cypress/e2e/adminTextLayout.cy.js

@@ -30,12 +30,31 @@ describe('The admin text detail page horizontal layout', () => {
   })
 
   it('stacks sibling child nodes vertically within the right column', () => {
+    cy.intercept('POST', '/api/nodes').as('createNode')
+    cy.intercept('GET', '/api/nodes/0').as('getNodesRefresh')
+
+    cy.get('#text-detail > ul > li')
+      .first()
+      .children('button.add-child')
+      .click()
+    cy.get('#text-detail > ul > li')
+      .first()
+      .children('input.child-title')
+      .type('Sibling One{enter}')
+    cy.wait('@createNode')
+    cy.wait('@getNodesRefresh')
+
+    cy.get('#text-detail > ul > li > ul > li').should(
+      'have.length.greaterThan',
+      1
+    )
+
     cy.get('#text-detail > ul > li > ul > li').then(($siblings) => {
-      expect($siblings.length).to.be.greaterThan(1)
       const firstRect = $siblings[0].getBoundingClientRect()
-      const secondRect = $siblings[1].getBoundingClientRect()
-      expect(secondRect.top).to.be.greaterThan(firstRect.top)
-      expect(Math.abs(secondRect.left - firstRect.left)).to.be.lessThan(2)
+      const lastRect = $siblings[$siblings.length - 1]
+        .getBoundingClientRect()
+      expect(lastRect.top).to.be.greaterThan(firstRect.top)
+      expect(Math.abs(lastRect.left - firstRect.left)).to.be.lessThan(2)
     })
   })
 })