fix(nav): put 'presentation' role on nav items

For the non-ng-container-based markup a `role="presentation"` should be added on the `li` elements.

Fixes ng-bootstrap#4398

src/index.ts

@@ -109,6 +109,7 @@ export {
 	NgbNavContent,
 	NgbNavContentContext,
 	NgbNavItem,
+	NgbNavItemRole,
 	NgbNavLink,
 	NgbNavLinkButton,
 	NgbNavLinkBase,

src/nav/nav.module.ts

@@ -1,13 +1,15 @@
 import { NgModule } from '@angular/core';
 
-import { NgbNav, NgbNavContent, NgbNavItem, NgbNavLink, NgbNavLinkButton, NgbNavLinkBase } from './nav';
+import { NgbNav, NgbNavContent, NgbNavItem, NgbNavItemRole, NgbNavLink, NgbNavLinkButton, NgbNavLinkBase } from './nav';
+
 import { NgbNavOutlet, NgbNavPane } from './nav-outlet';
 
 export {
 	NgbNav,
 	NgbNavContent,
 	NgbNavContentContext,
 	NgbNavItem,
+	NgbNavItemRole,
 	NgbNavLink,
 	NgbNavLinkButton,
 	NgbNavLinkBase,
@@ -20,6 +22,7 @@ const NGB_NAV_DIRECTIVES = [
 	NgbNavContent,
 	NgbNav,
 	NgbNavItem,
+	NgbNavItemRole,
 	NgbNavLink,
 	NgbNavLinkButton,
 	NgbNavLinkBase,

src/nav/nav.spec.ts

@@ -124,6 +124,7 @@ describe('nav', () => {
     `);
 
 		expect(getNav(fixture).getAttribute('role')).toBe('tablist');
+		expect(getItems(fixture)[0].getAttribute('role')).toBe('presentation');
 		expect(getLinks(fixture)[0].getAttribute('role')).toBe('tab');
 		expect(getContent(fixture).getAttribute('role')).toBe('tabpanel');
 	});
@@ -140,24 +141,26 @@ describe('nav', () => {
     `);
 
 		expect(getNav(fixture).getAttribute('role')).toBeNull();
+		expect(getItems(fixture)[0].getAttribute('role')).toBeNull();
 		expect(getLinks(fixture)[0].getAttribute('role')).toBeNull();
 		expect(getContent(fixture).getAttribute('role')).toBeNull();
 	});
 
 	it(`should allow overriding any A11Y roles`, () => {
 		const fixture = createTestComponent(`
       <ul ngbNav #n="ngbNav" role="list" class="nav-tabs">
-        <li ngbNavItem>
-            <button ngbNavLink role="alert"></button>
+        <li ngbNavItem role="myItemRole">
+            <button ngbNavLink role="myLinkRole"></button>
             <ng-template ngbTabContent></ng-template>
         </li>
       </ul>
-      <div [ngbNavOutlet]="n" paneRole="myRole"></div>
+      <div [ngbNavOutlet]="n" paneRole="myPaneRole"></div>
     `);
 
 		expect(getNav(fixture).getAttribute('role')).toBe('list');
-		expect(getLinks(fixture)[0].getAttribute('role')).toBe('alert');
-		expect(getContent(fixture).getAttribute('role')).toBe('myRole');
+		expect(getItems(fixture)[0].getAttribute('role')).toBe('myItemRole');
+		expect(getLinks(fixture)[0].getAttribute('role')).toBe('myLinkRole');
+		expect(getContent(fixture).getAttribute('role')).toBe('myPaneRole');
 	});
 
 	it(`should set orientation CSS and 'aria-orientation' correctly`, () => {

src/nav/nav.ts

@@ -55,6 +55,20 @@ export class NgbNavContent {
 	constructor(public templateRef: TemplateRef<any>) {}
 }
 
+/**
+ * This directive applies a specific role on a non-container based ngbNavItem.
+ */
+@Directive({
+	selector: '[ngbNavItem]:not(ng-container)',
+	standalone: true,
+	host: {
+		'[attr.role]': `role ? role : nav.roles ? 'presentation' : undefined`,
+	},
+})
+export class NgbNavItemRole {
+	constructor(@Attribute('role') public role: string, @Inject(forwardRef(() => NgbNav)) public nav: NgbNav) {}
+}
+
 /**
  * The directive used to group nav link and related nav content. As well as set nav identifier and some options.
  *