diff --git a/src/mock-doc/document.ts b/src/mock-doc/document.ts
index d9f59a63f2f..16d8b9eb481 100644
--- a/src/mock-doc/document.ts
+++ b/src/mock-doc/document.ts
@@ -42,6 +42,13 @@ export class MockDocument extends MockHTMLElement {
     }
   }
 
+  get dir() {
+    return this.documentElement.dir;
+  }
+  set dir(value: string) {
+    this.documentElement.dir = value;
+  }
+
   get location() {
     if (this.defaultView != null) {
       return (this.defaultView as Window).location;
diff --git a/src/mock-doc/test/element.spec.ts b/src/mock-doc/test/element.spec.ts
index fd972370bf5..768466566d1 100644
--- a/src/mock-doc/test/element.spec.ts
+++ b/src/mock-doc/test/element.spec.ts
@@ -9,6 +9,22 @@ describe('element', () => {
     doc = new MockDocument();
   });
 
+  it('document.documentElement dir', () => {
+    expect(doc.dir).toBe('');
+    expect(doc.documentElement.getAttribute('dir')).toBe(null);
+    doc.documentElement.setAttribute('dir', 'rtl');
+    expect(doc.documentElement.getAttribute('dir')).toBe('rtl');
+    expect(doc.dir).toBe('rtl');
+  });
+
+  it('document.dir', () => {
+    expect(doc.dir).toBe('');
+    doc.dir = 'ltr';
+    expect(doc.dir).toBe('ltr');
+    doc.dir = 'rtl';
+    expect(doc.dir).toBe('rtl');
+  });
+
   it('insertAdjacentElement beforebegin', () => {
     const elm = doc.createElement('div') as MockHTMLElement;
     elm.innerHTML = '<b>0</b>';