fix(mock-doc): add getAttributeNode to mock elements (#5070)

* fix(mock-doc): add `getAttributeNode` to mock elements

* add tests to mock-doc for `getAttributeNode`

src/mock-doc/node.ts

@@ -380,6 +380,14 @@ Testing components with ElementInternals is fully supported in e2e tests.`,
     return null;
   }
 
+  getAttributeNode(attrName: string): MockAttr | null {
+    if (!this.hasAttribute(attrName)) {
+      return null;
+    }
+
+    return new MockAttr(attrName, this.getAttribute(attrName));
+  }
+
   getBoundingClientRect() {
     return { bottom: 0, height: 0, left: 0, right: 0, top: 0, width: 0, x: 0, y: 0 };
   }

src/mock-doc/test/attribute.spec.ts

@@ -165,6 +165,24 @@ describe('attributes', () => {
     expect(img.draggable).toEqual(false);
   });
 
+  describe('getAttributeNode', () => {
+    it('should return an attribute node if the attribute exists', () => {
+      const div = doc.createElement('div');
+      div.setAttribute('draggable', 'true');
+      expect(div.getAttributeNode('draggable')).toEqual({
+        _name: 'draggable',
+        _namespaceURI: null,
+        _value: 'true',
+      });
+    });
+
+    it('should return `null` if the attribute does not exist', () => {
+      const div = doc.createElement('div');
+      div.setAttribute('draggable', 'true');
+      expect(div.getAttributeNode('test')).toEqual(null);
+    });
+  });
+
   function testNsAttributes(element: MockHTMLElement) {
     element.setAttributeNS('tEst', 'viewBox', '1');
     element.setAttributeNS('tEst', 'viewbox', '2');