The sad controller is tightly coupled to a specific implementation of the management class. We need to be coding against interfaces. This grants us at least two major wins: 1. We can refactor / improve the management class without worrying about the controller, we just need to ensure the interface is still satisfied. 2. We can test different par…

HappyController.cs

public sealed class HappyController : Controller {
  
  private IManagement management;
  
  public HappyController(IManagement management) {
    this.management = management
  }
  
  [HttpGet]
  public ViewResult LooselyCoupleThings() {
    return View(this.management.GetSomething());
  }
}

SadController.cs

public class SadController : Controller {
  
  [HttpGet]
  public ViewResult TightlyCoupleThings() {
    IEnumerable<string> something;
    
    using(var management = new Management()) {
      something = man.GetSomething();
    } 
    
    return View(something);
  }
}