Fix for foreignKey issue in #1685

lib/associations/has-one.js

@@ -22,7 +22,7 @@ module.exports = (function() {
     if (!this.options.foreignKey) {
       this.options.foreignKey = Utils._.camelizeIf(
         [
-          Utils._.underscoredIf(this.source.name, this.target.options.underscored),
+          Utils._.underscoredIf(Utils.singularize(this.source.name, this.target.options.language), this.target.options.underscored),
           this.source.primaryKeyAttribute
         ].join("_"),
         !this.source.options.underscored

test/associations/has-one.test.js

@@ -453,4 +453,23 @@ describe(Support.getTestDialectTeaser("HasOne"), function() {
     })
   })
 
+  describe("Counter part", function () {
+    describe("BelongsTo", function () {
+      it('should only generate one foreign key', function () {
+        var Orders = this.sequelize.define('Orders', {}, {timestamps: false})
+          , InternetOrders = this.sequelize.define('InternetOrders', {}, {timestamps: false})
+        
+        InternetOrders.belongsTo(Orders, {
+          foreignKeyConstraint: true
+        });
+        Orders.hasOne(InternetOrders, {
+          foreignKeyConstraint: true
+        });
+
+        expect(Object.keys(InternetOrders.rawAttributes).length).to.equal(2);
+        expect(InternetOrders.rawAttributes.OrderId).to.be.ok;
+        expect(InternetOrders.rawAttributes.OrdersId).not.to.be.ok;
+      })
+    })
+  })
 })