loopback-datasource-juggler/test/relations.test.js

// This test written in mocha+should.js
var should = require('./init.js');

var db, Book, Chapter, Author, Reader;
var Category, Product;
var Picture, PictureLink;

describe('relations', function () {

  describe('hasMany', function () {
    before(function (done) {
      db = getSchema();
      Book = db.define('Book', {name: String, type: String});
      Chapter = db.define('Chapter', {name: {type: String, index: true},
        bookType: String});
      Author = db.define('Author', {name: String});
      Reader = db.define('Reader', {name: String});

      db.automigrate(function () {
        Book.destroyAll(function () {
          Chapter.destroyAll(function () {
            Author.destroyAll(function () {
              Reader.destroyAll(done);
            });
          });
        });
      });
    });

    it('can be declared in different ways', function (done) {
      Book.hasMany(Chapter);
      Book.hasMany(Reader, {as: 'users'});
      Book.hasMany(Author, {foreignKey: 'projectId'});
      var b = new Book;
      b.chapters.should.be.an.instanceOf(Function);
      b.users.should.be.an.instanceOf(Function);
      b.authors.should.be.an.instanceOf(Function);
      Object.keys((new Chapter).toObject()).should.include('bookId');
      Object.keys((new Author).toObject()).should.include('projectId');

      db.automigrate(done);
    });

    it('can be declared in short form', function (done) {
      Author.hasMany('readers');
      (new Author).readers.should.be.an.instanceOf(Function);
      Object.keys((new Reader).toObject()).should.include('authorId');

      db.autoupdate(done);
    });

    it('should build record on scope', function (done) {
      Book.create(function (err, book) {
        var c = book.chapters.build();
        c.bookId.should.equal(book.id);
        c.save(done);
      });
    });

    it('should create record on scope', function (done) {
      Book.create(function (err, book) {
        book.chapters.create(function (err, c) {
          should.not.exist(err);
          should.exist(c);
          c.bookId.should.equal(book.id);
          done();
        });
      });
    });

    it('should fetch all scoped instances', function (done) {
      Book.create(function (err, book) {
        book.chapters.create({name: 'a'}, function () {
          book.chapters.create({name: 'z'}, function () {
            book.chapters.create({name: 'c'}, function () {
              verify(book);
            });
          });
        });
      });
      function verify(book) {
        book.chapters(function (err, ch) {
          should.not.exist(err);
          should.exist(ch);
          ch.should.have.lengthOf(3);

          book.chapters({order: 'name DESC'}, function (e, c) {
            should.not.exist(e);
            should.exist(c);
            c.shift().name.should.equal('z');
            c.pop().name.should.equal('a');
            done();
          });
        });
      }
    });

    it('should find scoped record', function (done) {
      var id;
      Book.create(function (err, book) {
        book.chapters.create({name: 'a'}, function (err, ch) {
          id = ch.id;
          book.chapters.create({name: 'z'}, function () {
            book.chapters.create({name: 'c'}, function () {
              verify(book);
            });
          });
        });
      });

      function verify(book) {
        book.chapters.findById(id, function (err, ch) {
          should.not.exist(err);
          should.exist(ch);
          ch.id.should.eql(id);
          done();
        });
      }
    });

    it('should set targetClass on scope property', function() {
      should.equal(Book.prototype.chapters._targetClass, 'Chapter');
    });

    it('should update scoped record', function (done) {
      var id;
      Book.create(function (err, book) {
        book.chapters.create({name: 'a'}, function (err, ch) {
          id = ch.id;
          book.chapters.updateById(id, {name: 'aa'}, function(err, ch) {
            verify(book);
          });
        });
      });

      function verify(book) {
        book.chapters.findById(id, function (err, ch) {
          should.not.exist(err);
          should.exist(ch);
          ch.id.should.eql(id);
          ch.name.should.equal('aa');
          done();
        });
      }
    });

    it('should destroy scoped record', function (done) {
      var id;
      Book.create(function (err, book) {
        book.chapters.create({name: 'a'}, function (err, ch) {
          id = ch.id;
          book.chapters.destroy(id, function(err, ch) {
            verify(book);
          });
        });
      });

      function verify(book) {
        book.chapters.findById(id, function (err, ch) {
          should.exist(err);
          done();
        });
      }
    });

    it('should check existence of a scoped record', function (done) {
      var id;
      Book.create(function (err, book) {
        book.chapters.create({name: 'a'}, function (err, ch) {
          id = ch.id;
          book.chapters.create({name: 'z'}, function () {
            book.chapters.create({name: 'c'}, function () {
              verify(book);
            });
          });
        });
      });

      function verify(book) {
        book.chapters.exists(id, function (err, flag) {
          should.not.exist(err);
          flag.should.be.eql(true);
          done();
        });
      }
    });
  });

  describe('hasMany through', function () {
    var Physician, Patient, Appointment;

    before(function (done) {
      db = getSchema();
      Physician = db.define('Physician', {name: String});
      Patient = db.define('Patient', {name: String});
      Appointment = db.define('Appointment', {date: {type: Date,
        default: function () {
          return new Date();
        }}});

      Physician.hasMany(Patient, {through: Appointment});
      Patient.hasMany(Physician, {through: Appointment});
      Appointment.belongsTo(Patient);
      Appointment.belongsTo(Physician);

      db.automigrate(['Physician', 'Patient', 'Appointment'], function (err) {
        done(err);
      });
    });

    it('should build record on scope', function (done) {
      Physician.create(function (err, physician) {
        var patient = physician.patients.build();
        patient.physicianId.should.equal(physician.id);
        patient.save(done);
      });
    });

    it('should create record on scope', function (done) {
      Physician.create(function (err, physician) {
        physician.patients.create(function (err, patient) {
          should.not.exist(err);
          should.exist(patient);
          Appointment.find({where: {physicianId: physician.id, patientId: patient.id}},
            function(err, apps) {
              should.not.exist(err);
              apps.should.have.lengthOf(1);
              done();
          });
        });
      });
    });

    it('should fetch all scoped instances', function (done) {
      Physician.create(function (err, physician) {
        physician.patients.create({name: 'a'}, function () {
          physician.patients.create({name: 'z'}, function () {
            physician.patients.create({name: 'c'}, function () {
              verify(physician);
            });
          });
        });
      });
      function verify(physician) {
        physician.patients(function (err, ch) {
          should.not.exist(err);
          should.exist(ch);
          ch.should.have.lengthOf(3);
          done();
        });
      }
    });

    it('should find scoped record', function (done) {
      var id;
      Physician.create(function (err, physician) {
        physician.patients.create({name: 'a'}, function (err, ch) {
          id = ch.id;
          physician.patients.create({name: 'z'}, function () {
            physician.patients.create({name: 'c'}, function () {
              verify(physician);
            });
          });
        });
      });

      function verify(physician) {
        physician.patients.findById(id, function (err, ch) {
          should.not.exist(err);
          should.exist(ch);
          ch.id.should.equal(id);
          done();
        });
      }
    });

    it('should set targetClass on scope property', function() {
      should.equal(Physician.prototype.patients._targetClass, 'Patient');
    });

    it('should update scoped record', function (done) {
      var id;
      Physician.create(function (err, physician) {
        physician.patients.create({name: 'a'}, function (err, ch) {
          id = ch.id;
          physician.patients.updateById(id, {name: 'aa'}, function(err, ch) {
            verify(physician);
          });
        });
      });

      function verify(physician) {
        physician.patients.findById(id, function (err, ch) {
          should.not.exist(err);
          should.exist(ch);
          ch.id.should.equal(id);
          ch.name.should.equal('aa');
          done();
        });
      }
    });

    it('should destroy scoped record', function (done) {
      var id;
      Physician.create(function (err, physician) {
        physician.patients.create({name: 'a'}, function (err, ch) {
          id = ch.id;
          physician.patients.destroy(id, function(err, ch) {
            verify(physician);
          });
        });
      });

      function verify(physician) {
        physician.patients.findById(id, function (err, ch) {
          should.exist(err);
          done();
        });
      }
    });

    it('should check existence of a scoped record', function (done) {
      var id;
      Physician.create(function (err, physician) {
        physician.patients.create({name: 'a'}, function (err, ch) {
          id = ch.id;
          physician.patients.create({name: 'z'}, function () {
            physician.patients.create({name: 'c'}, function () {
              verify(physician);
            });
          });
        });
      });

      function verify(physician) {
        physician.patients.exists(id, function (err, flag) {
          should.not.exist(err);
          flag.should.be.eql(true);
          done();
        });
      }
    });

    it('should allow to add connection with instance', function (done) {
      Physician.create({name: 'ph1'}, function (e, physician) {
        Patient.create({name: 'pa1'}, function (e, patient) {
          physician.patients.add(patient, function (e, app) {
            should.not.exist(e);
            should.exist(app);
            app.should.be.an.instanceOf(Appointment);
            app.physicianId.should.equal(physician.id);
            app.patientId.should.equal(patient.id);
            done();
          });
        });
      });
    });

    it('should allow to remove connection with instance', function (done) {
      var id;
      Physician.create(function (err, physician) {
        physician.patients.create({name: 'a'}, function (err, patient) {
          id = patient.id;
          physician.patients.remove(id, function (err, ch) {
            verify(physician);
          });
        });
      });

      function verify(physician) {
        physician.patients.exists(id, function (err, flag) {
          should.not.exist(err);
          flag.should.be.eql(false);
          done();
        });
      }
    });

    beforeEach(function (done) {
      Appointment.destroyAll(function (err) {
        Physician.destroyAll(function (err) {
          Patient.destroyAll(done);
        });
      });
    });

  });
  
  describe('hasMany with properties', function () {
    it('can be declared with properties', function (done) {
      Book.hasMany(Chapter, { properties: { type: 'bookType' } });
      db.automigrate(done);
    });
    
    it('should create record on scope', function (done) {
      Book.create({ type: 'fiction' }, function (err, book) {
        book.chapters.create(function (err, c) {
          should.not.exist(err);
          should.exist(c);
          c.bookId.should.equal(book.id);
          c.bookType.should.equal('fiction');
          done();
        });
      });
    });
  });

  describe('hasMany with scope and properties', function () {
    it('can be declared with properties', function (done) {
      db = getSchema();
      Category = db.define('Category', {name: String, productType: String});
      Product = db.define('Product', {name: String, type: String});

      Category.hasMany(Product, {
        properties: function(inst) {
          if (!inst.productType) return; // skip
          return { type: inst.productType };
        },
        scope: function(inst, filter) {
          var m = this.properties(inst); // re-use properties
          if (m) return { where: m };
        }
      });
      db.automigrate(done);
    });
    
    it('should create record on scope', function (done) {
      Category.create(function (err, c) {
        c.products.create({ type: 'book' }, function(err, p) {
          p.categoryId.should.equal(c.id);
          p.type.should.equal('book');
          c.products.create({ type: 'widget' }, function(err, p) {
            p.categoryId.should.equal(c.id);
            p.type.should.equal('widget');
            done();
          });
        });
      });
    });
    
    it('should find records on scope', function (done) {
      Category.findOne(function (err, c) {
        c.products(function(err, products) {
          products.should.have.length(2);
          done();
        });
      });
    });
    
    it('should find record on scope - filtered', function (done) {
      Category.findOne(function (err, c) {
        c.products({ where: { type: 'book' } }, function(err, products) {
          products.should.have.length(1);
          products[0].type.should.equal('book');
          done();
        });
      });
    });
    
    // So why not just do the above? In LoopBack, the context
    // that gets passed into a beforeRemote handler contains
    // a reference to the parent scope/instance: ctx.instance
    // in order to enforce a (dynamic scope) at runtime
    // a temporary property can be set in the beforeRemoting
    // handler. Optionally,properties dynamic properties can be declared.
    //
    // The code below simulates this.
    
    it('should create record on scope - properties', function (done) {
      Category.findOne(function (err, c) {
        c.productType = 'tool'; // temporary
        c.products.create(function(err, p) {
          p.categoryId.should.equal(c.id);
          p.type.should.equal('tool');
          done();
        });
      });
    });
    
    it('should find records on scope', function (done) {
      Category.findOne(function (err, c) {
        c.products(function(err, products) {
          products.should.have.length(3);
          done();
        });
      });
    });
    
    it('should find record on scope - scoped', function (done) {
      Category.findOne(function (err, c) {
        c.productType = 'book'; // temporary, for scoping
        c.products(function(err, products) {
          products.should.have.length(1);
          products[0].type.should.equal('book');
          done();
        });
      });
    });
    
    it('should find record on scope - scoped', function (done) {
      Category.findOne(function (err, c) {
        c.productType = 'tool'; // temporary, for scoping
        c.products(function(err, products) {
          products.should.have.length(1);
          products[0].type.should.equal('tool');
          done();
        });
      });
    });
    
    it('should delete records on scope - scoped', function (done) {
      Category.findOne(function (err, c) {
        c.productType = 'tool'; // temporary, for scoping
        c.products.destroyAll(function(err, result) {
          done();
        });
      });
    });
    
    it('should find record on scope - verify', function (done) {
      Category.findOne(function (err, c) {
        c.products(function(err, products) {
          products.should.have.length(2);
          done();
        });
      });
    });
  
  });
  
  describe('polymorphic hasMany', function () {
    before(function (done) {
      db = getSchema();
      Picture = db.define('Picture', {name: String});
      Author = db.define('Author', {name: String});
      Reader = db.define('Reader', {name: String});

      db.automigrate(function () {
        Picture.destroyAll(function () {
          Author.destroyAll(function () {
            Reader.destroyAll(done);
          });
        });
      });
    });

    it('can be declared', function (done) {
      Author.hasMany(Picture, { polymorphic: 'imageable' });
      Reader.hasMany(Picture, { polymorphic: 'imageable' });
      Picture.belongsTo('imageable', { polymorphic: true });
      db.automigrate(done);
    });
    
    it('should create polymorphic relation - author', function (done) {
      Author.create({ name: 'Author 1' }, function (err, author) {
        author.pictures.create({ name: 'Author Pic' }, function (err, p) {
          should.not.exist(err);
          should.exist(p);
          p.imageableId.should.equal(author.id);
          p.imageableType.should.equal('Author');
          done();
        });
      });
    });
    
    it('should create polymorphic relation - reader', function (done) {
      Reader.create({ name: 'Reader 1' }, function (err, reader) {
        reader.pictures.create({ name: 'Reader Pic' }, function (err, p) {
          should.not.exist(err);
          should.exist(p);
          p.imageableId.should.equal(reader.id);
          p.imageableType.should.equal('Reader');
          done();
        });
      });
    });
    
    it('should find polymorphic items - author', function (done) {
      Author.findOne(function (err, author) {
        author.pictures(function (err, pics) {
          should.not.exist(err);
          pics.should.have.length(1);
          pics[0].name.should.equal('Author Pic');
          done();
        });
      });
    });
    
    it('should find polymorphic items - reader', function (done) {
      Reader.findOne(function (err, reader) {
        reader.pictures(function (err, pics) {
          should.not.exist(err);
          pics.should.have.length(1);
          pics[0].name.should.equal('Reader Pic');
          done();
        });
      });
    });
    
    it('should find the inverse of polymorphic relation - author', function (done) {
      Picture.findOne({ where: { name: 'Author Pic' } }, function (err, p) {
        should.not.exist(err);
        p.imageableType.should.equal('Author');
        p.imageable(function(err, imageable) {
          should.not.exist(err);
          imageable.should.be.instanceof(Author);
          imageable.name.should.equal('Author 1');
          done();
        });
      });
    });
    
    it('should find the inverse of polymorphic relation - reader', function (done) {
      Picture.findOne({ where: { name: 'Reader Pic' } }, function (err, p) {
        should.not.exist(err);
        p.imageableType.should.equal('Reader');
        p.imageable(function(err, imageable) {
          should.not.exist(err);
          imageable.should.be.instanceof(Reader);
          imageable.name.should.equal('Reader 1');
          done();
        });
      });
    });
    
    it('should include the inverse of polymorphic relation', function (done) {
      Picture.find({ include: 'imageable' }, function (err, pics) {
        should.not.exist(err);
        pics.should.have.length(2);
        pics[0].name.should.equal('Author Pic');
        pics[0].imageable().name.should.equal('Author 1');
        pics[1].name.should.equal('Reader Pic');
        pics[1].imageable().name.should.equal('Reader 1');
        done();
      });
    });
    
    it('should assign a polymorphic relation', function(done) {
      Author.create({ name: 'Author 2' }, function(err, author) {
        var p = new Picture({ name: 'Sample' });
        p.imageable(author); // assign
        p.imageableId.should.equal(author.id);
        p.imageableType.should.equal('Author');
        p.save(done);
      });
    });
    
    it('should find polymorphic items - author', function (done) {
      Author.findOne({ where: { name: 'Author 2' } }, function (err, author) {
        author.pictures(function (err, pics) {
          should.not.exist(err);
          pics.should.have.length(1);
          pics[0].name.should.equal('Sample');
          done();
        });
      });
    });
    
    it('should find the inverse of polymorphic relation - author', function (done) {
      Picture.findOne({ where: { name: 'Sample' } }, function (err, p) {
        should.not.exist(err);
        p.imageableType.should.equal('Author');
        p.imageable(function(err, imageable) {
          should.not.exist(err);
          imageable.should.be.instanceof(Author);
          imageable.name.should.equal('Author 2');
          done();
        });
      });
    });
    
  });
  
  describe('polymorphic hasAndBelongsToMany through', function () {
    before(function (done) {
      db = getSchema();
      Picture = db.define('Picture', {name: String});
      Author = db.define('Author', {name: String});
      Reader = db.define('Reader', {name: String});
      PictureLink = db.define('PictureLink', {});

      db.automigrate(function () {
        Picture.destroyAll(function () {
          PictureLink.destroyAll(function () {
            Author.destroyAll(function () {
              Reader.destroyAll(done);
            });
          });
        });
      });
    });

    it('can be declared', function (done) {
      Author.hasAndBelongsToMany(Picture, { through: PictureLink, polymorphic: 'imageable' });
      Reader.hasAndBelongsToMany(Picture, { through: PictureLink, polymorphic: 'imageable' });
      db.automigrate(done);
    });
    
    it('should create polymorphic relation - author', function (done) {
      Author.create({ id: 3, name: 'Author 1' }, function (err, author) {
        author.pictures.create({ name: 'Author Pic 1' }, function (err, p) {
          should.not.exist(err);
          p.id.should.equal(1);
          author.pictures.create({ name: 'Author Pic 2' }, function (err, p) {
            should.not.exist(err);
            p.id.should.equal(2);
            done();
          });
        });
      });
    });
    
    it('should create polymorphic relation - reader', function (done) {
      Reader.create({ id: 4, name: 'Reader 1' }, function (err, reader) {
        reader.pictures.create({ name: 'Reader Pic 1' }, function (err, p) {
          should.not.exist(err);
          p.id.should.equal(3);
          done();
        });
      });
    });
    
    it('should create polymorphic through model', function (done) {
      PictureLink.findOne(function(err, link) {
        should.not.exist(err);
        link.pictureId.should.equal(1);
        link.imageableId.should.equal(3);
        link.imageableType.should.equal('Author');
        done();
      });
    });
    
    it('should get polymorphic relation through model - author', function (done) {
      Author.findById(3, function(err, author) {
        should.not.exist(err);
        author.name.should.equal('Author 1');
        author.pictures(function(err, pics) {
          should.not.exist(err);
          pics.should.have.length(2);
          pics[0].name.should.equal('Author Pic 1');
          pics[1].name.should.equal('Author Pic 2');
          done();
        });
      });
    });
    
    it('should get polymorphic relation through model - reader', function (done) {
      Reader.findById(4, function(err, reader) {
        should.not.exist(err);
        reader.name.should.equal('Reader 1');
        reader.pictures(function(err, pics) {
          should.not.exist(err);
          pics.should.have.length(1);
          pics[0].name.should.equal('Reader Pic 1');
          done();
        });
      });
    });
  
  });

  describe('belongsTo', function () {
    var List, Item, Fear, Mind;

    it('can be declared in different ways', function () {
      List = db.define('List', {name: String});
      Item = db.define('Item', {name: String});
      Fear = db.define('Fear');
      Mind = db.define('Mind');

      // syntax 1 (old)
      Item.belongsTo(List);
      Object.keys((new Item).toObject()).should.include('listId');
      (new Item).list.should.be.an.instanceOf(Function);

      // syntax 2 (new)
      Fear.belongsTo('mind');
      Object.keys((new Fear).toObject()).should.include('mindId');
      (new Fear).mind.should.be.an.instanceOf(Function);
      // (new Fear).mind.build().should.be.an.instanceOf(Mind);
    });

    it('can be used to query data', function (done) {
      List.hasMany('todos', {model: Item});
      db.automigrate(function () {
        List.create(function (e, list) {
          should.not.exist(e);
          should.exist(list);
          list.todos.create(function (err, todo) {
            todo.list(function (e, l) {
              should.not.exist(e);
              should.exist(l);
              l.should.be.an.instanceOf(List);
              todo.list().id.should.equal(l.id);
              done();
            });
          });
        });
      });
    });

    it('could accept objects when creating on scope', function (done) {
      List.create(function (e, list) {
        should.not.exist(e);
        should.exist(list);
        Item.create({list: list}, function (err, item) {
          should.not.exist(err);
          should.exist(item);
          should.exist(item.listId);
          item.listId.should.equal(list.id);
          item.__cachedRelations.list.should.equal(list);
          done();
        });
      });
    });

  });
  
  describe('belongsTo with scope', function () {
    var Person, Passport;
    
    it('can be declared with scope and properties', function (done) {
      Person = db.define('Person', {name: String, age: Number});
      Passport = db.define('Passport', {name: String, notes: String});
      Passport.belongsTo(Person, {
        properties: { notes: 'passportNotes' },
        scope: { fields: { id: true, name: true } }
      });
      db.automigrate(done);
    });
    
    it('should create record on scope', function (done) {
      var p = new Passport({ name: 'Passport', notes: 'Some notes...' });
      p.person.create({ id: 3, name: 'Fred', age: 36 }, function(err, person) {
        p.personId.should.equal(person.id);
        p.save(function (err, p) {
          person.name.should.equal('Fred');
          person.passportNotes.should.equal('Some notes...');
          done();
        });
      });
    });
    
    it('should find record on scope', function (done) {
      Passport.findOne(function (err, p) {
        p.personId.should.equal(3);
        p.person(function(err, person) {
          person.name.should.equal('Fred');
          person.should.not.have.property('age');
          person.should.not.have.property('passportNotes');
          done();
        });
      });
    });
  
  });

  describe('hasOne', function () {
    var Supplier, Account;

    before(function () {
      db = getSchema();
      Supplier = db.define('Supplier', {name: String});
      Account = db.define('Account', {accountNo: String, supplierName: String});
    });

    it('can be declared using hasOne method', function () {
      Supplier.hasOne(Account, { properties: { name: 'supplierName' } });
      Object.keys((new Account()).toObject()).should.include('supplierId');
      (new Supplier()).account.should.be.an.instanceOf(Function);
    });

    it('can be used to query data', function (done) {
      // Supplier.hasOne(Account);
      db.automigrate(function () {
        Supplier.create({name: 'Supplier 1'}, function (e, supplier) {
          should.not.exist(e);
          should.exist(supplier);
          supplier.account.create({accountNo: 'a01'}, function (err, account) {
            supplier.account(function (e, act) {
              should.not.exist(e);
              should.exist(act);
              act.should.be.an.instanceOf(Account);
              supplier.account().id.should.equal(act.id);
              act.supplierName.should.equal(supplier.name);
              done();
            });
          });
        });
      });
    });

    it('should set targetClass on scope property', function() {
      should.equal(Supplier.prototype.account._targetClass, 'Account');
    });
  });

  describe('hasAndBelongsToMany', function () {
    var Article, Tag, ArticleTag;
    it('can be declared', function (done) {
      Article = db.define('Article', {title: String});
      Tag = db.define('Tag', {name: String});
      Article.hasAndBelongsToMany('tags');
      ArticleTag = db.models.ArticleTag;
      db.automigrate(function () {
        Article.destroyAll(function () {
          Tag.destroyAll(function () {
            ArticleTag.destroyAll(done)
          });
        });
      });
    });

    it('should allow to create instances on scope', function (done) {
      Article.create(function (e, article) {
        article.tags.create({name: 'popular'}, function (e, t) {
          t.should.be.an.instanceOf(Tag);
          // console.log(t);
          ArticleTag.findOne(function (e, at) {
            should.exist(at);
            at.tagId.toString().should.equal(t.id.toString());
            at.articleId.toString().should.equal(article.id.toString());
            done();
          });
        });
      });
    });

    it('should allow to fetch scoped instances', function (done) {
      Article.findOne(function (e, article) {
        article.tags(function (e, tags) {
          should.not.exist(e);
          should.exist(tags);
          done();
        });
      });
    });

    it('should allow to add connection with instance', function (done) {
      Article.findOne(function (e, article) {
        Tag.create({name: 'awesome'}, function (e, tag) {
          article.tags.add(tag, function (e, at) {
            should.not.exist(e);
            should.exist(at);
            at.should.be.an.instanceOf(ArticleTag);
            at.tagId.should.equal(tag.id);
            at.articleId.should.equal(article.id);
            done();
          });
        });
      });
    });

    it('should allow to remove connection with instance', function (done) {
      Article.findOne(function (e, article) {
        article.tags(function (e, tags) {
          var len = tags.length;
          tags.should.not.be.empty;
          article.tags.remove(tags[0], function (e) {
            should.not.exist(e);
            article.tags(true, function (e, tags) {
              tags.should.have.lengthOf(len - 1);
              done();
            });
          });
        });
      });
    });

    it('should set targetClass on scope property', function() {
      should.equal(Article.prototype.tags._targetClass, 'Tag');
    });
  });

});