c# - Unit Test for Event handlers -

i want test whether event has raised or not using unit testing. in project, passed progress value 1 class using event handler. working on mvvm method so, passed value model class viewmodel class. how write unit test event handler.

i try write unit test event handlers called gettotalfilesize , transferredfilesize.but not raise events on test. so, have do?

    [test]     public void isgettotalfilesizeeventfired()     {         worflowmanager = new mock<iworkflowmanager>().object;         ripwatcherwindowshellviewmodel =          new ripwatcherwindowshellviewmodel(worflowmanager);          ripwatcherwindowshellviewmodel.gettotalfilesize           += delegate { eventraised = true; };          assert.istrue(eventraised);     } 

//production code is..

       public ripwatcherwindowshellviewmodel(iworkflowmanager workflowmanager)        {            workflowmanager = workflowmanager;                                                  workflowmanager.transferredusffilesizechanged             += workflowmanager_transferredusffilesizechanged;             workflowmanager.gettotalusffilesize             += workflowmanager_gettotalfilesize;        }          public void workflowmanager_gettotalfilesize(object sender, filesizechangedeventargs e)     {         if(e.filesize== 0)         {             throw new argumentexception("we cannot calculate progress percentage because total file size 0");         }         totalusffilesize = e.filesize;     }       public void workflowmanager_transferredusffilesizechanged(object sender, filesizechangedeventargs e)     {         if(e.filesize !=0)         {             transferredusffilesize = e.filesize;         }         else         {             tempfilesize += transferredusffilesize;         }                     /*calculating progress percentage updating progress bar*/         progresspercentage = (int)(((totalusffilesize -(totalusffilesize-(tempfilesize+transferredusffilesize)))/totalusffilesize)* 100);     }              public double transferredusffilesize     {         get;         set;     }      /// <summary>gets or sets total file size</summary>     public double totalusffilesize     {         get;         set;     }      public iworkflowmanager workflowmanager { get; set; }      public int progresspercentage     {                 {             return percentage;         }         set         {             percentage = value;             onpropertychanged("progresspercentage");         }     } 

the value came from..

     public void copyex(string sourcefilepath,string destinationfilepath)     {         try         {             lock (locker)             {                 copyfileex(sourcefilepath, destinationfilepath,                 new copyprogressroutine(this.copyprogresshandler),                  intptr.zero, ref pbcancel,                 copyfileflags.copy_file_restartable);             }         }         catch(exception ex)         {             throw new exception(ex.message);         }     }      private copyprogressresult copyprogresshandler(long total,              long transferredfilesize, long streamsize,              long streambytetrans, uint dwstreamnumber,               copyprogresscallbackreason reason,               intptr hsourcefile, intptr hdestinationfile, intptr lpdata)     {         transferredusffilesizechanged.safeinvoke(this,         new filesizechangedeventargs(transferredfilesize));                      return copyprogressresult.progress_continue;     }      public eventhandler<filesizechangedeventargs>      transferredusffilesizechanged;