text: describe('docking station', function() {
  
    var docking_station;
    var bike;
    var bikes = [];
  
    beforeEach(function() {
      docking_station = new Docking_station();
      bike = new Bike();
    })
  
    it('can release a bike', function() {
      docking_station.dock(bike);
      docking_station.release_bike(bike);
      expect(docking_station.bikes).not.toContain(bike);
    })
  
    it('can dock a bike', function() {
      docking_station.dock(bike);
      expect(docking_station.bikes).toContain(bike)
    })
  
    it('can advise when no bikes are available', function() {
      expect(docking_station.release_bike).toThrowError('No bikes available.');
    })
  
    it('raises an error when full and has a maximum capacity of 20', function() {
      for(var i = 0; i < 19; i++) {
      docking_station.dock(bike);
      }
  
      docking_station.dock(bike);
      expect(docking_station.dock).toThrowError('Docking station full.');
    })
  
    it('has variable capacity', function() {
      docking_station.capacity = 5;
      for(var i = 0; i < 4; i++){
      docking_station.dock(bike);
      }
  
      docking_station.dock(bike);
      expect(docking_station.dock).toThrowError('Docking station full.');
    })
  
  })
  