diff --git a/lib/utils/validation-utils.test.js b/lib/utils/validation-utils.test.js
--- a/lib/utils/validation-utils.test.js
+++ b/lib/utils/validation-utils.test.js
@@ -2,7 +2,11 @@
 
 import { threadTypes } from '../types/thread-types';
 import { values } from '../utils/objects';
-import { tNumEnum } from './validation-utils';
+import {
+  tMediaMessagePhoto,
+  tMediaMessageVideo,
+  tNumEnum,
+} from './validation-utils';
 
 describe('Validation utils', () => {
   describe('tNumEnum validator', () => {
@@ -26,4 +30,113 @@
       expect(tNumEnum(values(threadTypes)).is(123)).toBe(false);
     });
   });
+
+  describe('tMediaMessagePhoto validator', () => {
+    it('Should succeed when valid MediaMessagePhoto', () => {
+      expect(tMediaMessagePhoto.is({ type: 'photo', uploadID: '12345' })).toBe(
+        true,
+      );
+    });
+
+    it('Should fail when missing uploadID', () => {
+      expect(tMediaMessagePhoto.is({ type: 'photo' })).toBe(false);
+    });
+
+    it('Should fail when uploadID is not a string', () => {
+      expect(tMediaMessagePhoto.is({ type: 'photo', uploadID: 12345 })).toBe(
+        false,
+      );
+    });
+
+    it('Should fail when type is not photo', () => {
+      expect(tMediaMessagePhoto.is({ type: 'blah', uploadID: '12345' })).toBe(
+        false,
+      );
+    });
+
+    it('Should fail when type is video', () => {
+      expect(tMediaMessagePhoto.is({ type: 'video', uploadID: '12345' })).toBe(
+        false,
+      );
+    });
+  });
+
+  describe('tMediaMessageVideo validator', () => {
+    it('Should succeed when valid tMediaMessageVideo', () => {
+      expect(
+        tMediaMessageVideo.is({
+          type: 'video',
+          uploadID: '12345',
+          thumbnailUploadID: '7890',
+        }),
+      ).toBe(true);
+    });
+
+    it('Should fail when missing thumbnailUploadID', () => {
+      expect(
+        tMediaMessageVideo.is({
+          type: 'video',
+          uploadID: '12345',
+        }),
+      ).toBe(false);
+    });
+
+    it('Should fail when uploadID is not a string', () => {
+      expect(
+        tMediaMessageVideo.is({
+          type: 'video',
+          uploadID: 12345,
+          thumbnailUploadID: '7890',
+        }),
+      ).toBe(false);
+    });
+
+    it('Should fail when type is not video', () => {
+      expect(
+        tMediaMessageVideo.is({
+          type: 'blah',
+          uploadID: '12345',
+          thumbnailUploadID: '7890',
+        }),
+      ).toBe(false);
+    });
+
+    it('Should fail when type is photo', () => {
+      expect(
+        tMediaMessageVideo.is({
+          type: 'photo',
+          uploadID: '12345',
+          thumbnailUploadID: '7890',
+        }),
+      ).toBe(false);
+    });
+  });
+
+  describe('tMediaMessageMedia validator', () => {
+    it('Should succeed when valid MediaMessagePhoto', () => {
+      expect(tMediaMessagePhoto.is({ type: 'photo', uploadID: '12345' })).toBe(
+        true,
+      );
+    });
+
+    it('Should succeed when valid tMediaMessageVideo', () => {
+      expect(
+        tMediaMessageVideo.is({
+          type: 'video',
+          uploadID: '12345',
+          thumbnailUploadID: '7890',
+        }),
+      ).toBe(true);
+    });
+
+    it('Should fail when not valid MediaMessagePhoto or tMediaMessageVideo', () => {
+      expect(
+        tMediaMessageVideo.is({
+          type: 'audio',
+          uploadID: '1000',
+          thumbnailUploadID: '1000',
+        }),
+      ).toBe(false);
+    });
+  });
 });