users: add unset route for avatar

also add missing tests for avatar and profile locking

src/test/users-test.js

@@ -578,6 +578,32 @@ describe('User', function () {
         });
     });
 
+    describe('avatar', function () {
+        before(createOwner);
+
+        it('default avatar is empty', async function () {
+            const result = await users.get(admin.id);
+            expect(result.avatar).to.be(undefined); // should not be in 'get'
+
+            const result2 = await users.getAvatar(result);
+            expect(result2).to.be(null);
+        });
+
+        it('set avatar', async function () {
+            await users.setAvatar(admin, Buffer.from('ABC'));
+
+            const avatar = await users.getAvatar(admin);
+            expect(avatar).to.be.eql(Buffer.from('ABC'));
+        });
+
+        it('reset avatar', async function () {
+            await users.setAvatar(admin, null);
+
+            const avatar = await users.getAvatar(admin);
+            expect(avatar).to.be(null);
+        });
+    });
+
     describe('invite', function () {
         before(createOwner);