lowercase onDelete option before cheking its value

changelog.md

 # Next
 - [FIXED] Apply scopes to `aggregate` [#4764](https://github.com/sequelize/sequelize/issues/4764)
+- [ADDED/FIXED] Lower case `onDelete` option to allow the use of `onDelete: 'CASCADE', hooks: true`.
 
 # 3.13.0
 - [FIXED] timestamp columns are no longer undefined for associations loaded with `separate`. [#4740](https://github.com/sequelize/sequelize/issues/4740)

lib/query-interface.js

@@ -629,13 +629,15 @@ QueryInterface.prototype.delete = function(instance, tableName, identifier, opti
   // Check for a restrict field
   if (!!instance.Model && !!instance.Model.associations) {
     var keys = Object.keys(instance.Model.associations)
-      , length = keys.length;
+      , length = keys.length
+      , association;
 
     for (var i = 0; i < length; i++) {
-      if (instance.Model.associations[keys[i]].options && instance.Model.associations[keys[i]].options.onDelete) {
-        if (instance.Model.associations[keys[i]].options.onDelete === 'cascade' && instance.Model.associations[keys[i]].options.useHooks === true) {
-          cascades.push(instance.Model.associations[keys[i]].accessors.get);
-        }
+      association = instance.Model.associations[keys[i]];
+      if (association.options && association.options.onDelete &&
+        association.options.onDelete.toLowerCase() === 'cascade' &&
+        association.options.useHooks === true) {
+        cascades.push(association.accessors.get);
       }
     }
   }

test/integration/hooks.test.js

@@ -1122,7 +1122,7 @@ describe(Support.getTestDialectTeaser('Hooks'), function() {
             title: DataTypes.STRING
           });
 
-          this.Projects.hasOne(this.Tasks, {onDelete: 'cascade', hooks: true});
+          this.Projects.hasOne(this.Tasks, {onDelete: 'CASCADE', hooks: true});
           this.Tasks.belongsTo(this.Projects);
 
           return this.sequelize.sync({ force: true });