Add test coverage for `validatesInclusionOf` (#1249)

* Fix indentation

* Improve tests formatting

* Use instanceof and should.match

test/validations.test.js

@@ -610,7 +610,55 @@ describe('validations', function() {
   });
 
   describe('inclusion', function() {
-    it('should validate inclusion');
+    it('fails when included value is not used for property', function(done) {
+      User.validatesInclusionOf('name', {in: ['bob', 'john']});
+      User.create({name: 'bobby'}, function(err) {
+        err.should.be.instanceof(Error);
+        err.details.messages.should.match({name: /is not included in the list/});
+        done();
+      });
+    });
+
+    it('passes when included value is used for property', function(done) {
+      User.validatesInclusionOf('name', {in: ['bob', 'john']});
+      User.create({name: 'bob'}, function(err, user) {
+        if (err) return done(err);
+        user.name.should.eql('bob');
+        done();
+      });
+    });
+
+    it('fails with a custom error message', function(done) {
+      User.validatesInclusionOf('name', {in: ['bob', 'john'], message: 'not used'});
+      User.create({name: 'dude'}, function(err) {
+        err.should.be.instanceof(Error);
+        err.details.messages.should.match({name: /not used/});
+        done();
+      });
+    });
+
+    it('fails with a null value when allowNull is false', function(done) {
+      User.validatesInclusionOf('name', {in: ['bob'], allowNull: false});
+      User.create({name: null}, function(err) {
+        err.should.be.instanceof(Error);
+        err.details.messages.should.match({name: /is null/});
+        done();
+      });
+    });
+
+    it('passes with a null value when allowNull is true', function(done) {
+      User.validatesInclusionOf('name', {in: ['bob'], allowNull: true});
+      User.create({name: null}, done);
+    });
+
+    it('fails if value is used for integer property', function(done) {
+      User.validatesInclusionOf('age', {in: [123, 456]});
+      User.create({age: 789}, function(err) {
+        err.should.be.instanceof(Error);
+        err.details.messages.should.match({age: /is not included in the list/});
+        done();
+      });
+    });
   });
 
   describe('exclusion', function() {