test child add keeps parent expanded

assert that a non-root parent that the user expanded stays expanded
after adding a child. currently fails: fetchAndRenderNodes wipes
and rebuilds the tree with depth-based default visibility, so any
manually expanded non-root collapses on every save.

cypress/e2e/adminText.cy.js

@@ -65,6 +65,42 @@ describe('The admin text detail page', () => {
     cy.get('#text-detail li').should('contain', 'Nested Child Node')
   })
 
+  it('keeps a parent expanded after adding a child to it', () => {
+    cy.intercept('POST', '/api/nodes').as('createNode')
+    cy.intercept('GET', '/api/nodes/0').as('getNodesRefresh')
+
+    cy.get('#text-detail > ul > li > ul > li')
+      .first()
+      .find('button.toggle-children')
+      .click()
+    cy.get('#text-detail > ul > li > ul > li > ul')
+      .first()
+      .should('be.visible')
+
+    cy.get('#text-detail > ul > li > ul > li')
+      .first()
+      .children('button.add-child')
+      .click()
+    cy.get('#text-detail > ul > li > ul > li')
+      .first()
+      .children('input.child-title')
+      .type('Shemos')
+    cy.get('#text-detail > ul > li > ul > li')
+      .first()
+      .children('button.save-child')
+      .click()
+
+    cy.wait('@createNode').its('response.statusCode').should('eq', 201)
+    cy.wait('@getNodesRefresh')
+
+    cy.get('#text-detail > ul > li > ul > li > ul')
+      .first()
+      .should('be.visible')
+    cy.get('#text-detail > ul > li > ul > li > ul')
+      .first()
+      .should('contain', 'Shemos')
+  })
+
   it('newly added child persists after page reload', () => {
     cy.intercept('POST', '/api/nodes').as('createNode')
     cy.intercept('GET', '/api/nodes/0').as('getNodesRefresh')