Add accessibility testing for admin sidebar

(cherry picked from commit 31bc05235e)

cypress/e2e/admin-sidebar.cy.ts

@@ -0,0 +1,28 @@
+import { Options } from 'cypress-axe';
+import { testA11y } from 'cypress/support/utils';
+
+describe('Admin Sidebar', () => {
+    beforeEach(() => {
+        // Must login as an Admin for sidebar to appear
+        cy.visit('/login');
+        cy.loginViaForm(Cypress.env('DSPACE_TEST_ADMIN_USER'), Cypress.env('DSPACE_TEST_ADMIN_PASSWORD'));
+    });
+
+    it('should be pinnable and pass accessibility tests', () => {
+        // Pin the sidebar open
+        cy.get('#sidebar-collapse-toggle').click();
+
+        // Click on every expandable section to open all menus
+        cy.get('ds-expandable-admin-sidebar-section').click({multiple: true});
+
+        // Analyze <ds-admin-sidebar> for accessibility
+        testA11y('ds-admin-sidebar',
+        {
+            rules: {
+                // Currently all expandable sections have nested interactive elements
+                // See https://github.com/DSpace/dspace-angular/issues/2178
+                'nested-interactive': { enabled: false },
+            }
+        } as Options);
+    });
+});