profile: store preferred language in the database

src/test/users-test.js

@@ -553,6 +553,32 @@ describe('User', function () {
         });
     });
 
+    describe('language', function () {
+        before(createOwner);
+
+        it('default language is empty', async function () {
+            const result = await users.get(admin.id);
+            expect(result.language).to.be('');
+        });
+
+        it('cannot set bad language', async function () {
+            const [error] = await safe(users.update(admin, { language: 'ta '}, auditSource));
+            expect(error.reason).to.be(BoxError.BAD_FIELD);
+        });
+
+        it('can set language', async function () {
+            await users.update(admin, { language: 'en' }, auditSource);
+            const result = await users.get(admin.id);
+            expect(result.language).to.be('en');
+        });
+
+        it('can reset language', async function () {
+            await users.update(admin, { language: '' }, auditSource);
+            const result = await users.get(admin.id);
+            expect(result.language).to.be('');
+        });
+    });
+
     describe('invite', function () {
         before(createOwner);