validate whether array has only unique items (#89)

* validate whether array has only unique items

* add example property, group with bool opts

docs/validation/array-validations.md

@@ -2,6 +2,7 @@
 
 - `required`: can't be undefined (default: `false`)
 - `sparse`: can have undefined items (default: `true`)
+- `unique`: can't have duplicate items (default: `false`)
 - `minLength`: minimum quantity of items
 - `maxLength`: maximum quantity of items
 - `exactLength`: exact quantity of items
@@ -13,7 +14,8 @@ const Group = attributes({
     itemType: String,
     minLength: 2,
     maxLength: 5,
-    sparse: false
+    sparse: false,
+    unique: true
   },
   leaders: {
     type: Array,

src/validation/array.js

@@ -5,6 +5,8 @@ const joiMappings = [
   ['minLength', 'min', true],
   ['maxLength', 'max', true],
   ['exactLength', 'length', true],
+  ['unique', 'unique']
+
 ];
 
 module.exports = function arrayValidation(typeDescriptor, itemTypeDescriptor) {

test/unit/validation/array.spec.js

@@ -377,5 +377,42 @@ describe('validation', () => {
         });
       });
     });
+    describe('unique', () => {
+      var User;
+
+      beforeEach(() => {
+        User = attributes({
+          books: {
+            type: Array,
+            itemType: String,
+            unique: true
+          }
+        })(class User {});
+      });
+      context('when array is unique', () => {
+        it('is valid', () => {
+          const user = new User({
+            books: [
+              'The Gunslinger',
+              'The Drawing of the Three'
+            ]
+          });
+
+          assertValid(user);
+        });
+      });
+      context('when array is not unique', () => {
+        it('is not valid and has errors set', () => {
+          const user = new User({
+            books: [
+              'The Wastelands',
+              'The Wastelands'
+            ]
+          });
+
+          assertInvalid(user, 'books.1');
+        });
+      });
+    });
   });
 });