Как подождать завершения потоков ?

unit testlib;
 
interface
 
uses
  SysUtils,
  Classes,
  System.syncobjs,
  windows,
  System.Generics.Collections;
 
type
 Ttestlib= class
private
published
function Testy(const threads:integer): string;
constructor Create;
destructor Destroy; override;
end;
 
type
th = class(TThread)
private
protected
  procedure Execute; Override;
public
  constructor create(createsuspended:boolean);
end;
 
var
work:boolean=true;
Event: THandle;
cs:TcriticalSection;
 
implementation
 
{ th }
 
constructor th.create(createsuspended: boolean);
begin
inherited Create(CreateSuspended);
FreeOnTerminate := True;
end;
 
procedure th.Execute;
begin
inherited;
while work do begin
cs.Enter;
//КОД
cs.Leave;
if work then begin
//КОД
end;
end;
end;
 
{ Ttestlib }
 
constructor Ttestlib.Create;
begin
//Создадим нужные компоненты
end;
 
destructor Ttestlib.Destroy;
begin
inherited;
work:=False;
//Освободим Нужные компоненты
end;
 
function Ttestlib.Testy(const threads:integer): string;
var
i:integer;
thrs:th;
begin
Result:='';
ResetEvent(Event);
for I := 0 to threads-1 do begin
thrs:=th.create(False);
// Костыль ожидания завершения всех потоков:
Win32Check(DuplicateHandle(
      GetCurrentProcess,
      thrs.Handle,
      GetCurrentProcess,
      @Event,
      0,
      False,
      DUPLICATE_SAME_ACCESS
    ));
  end;
thrs.FreeOnTerminate:=True;
WaitForSingleObject(Event, INFINITE); // Само ожидание
CloseHandle(Event);
Result:='ГОТОВО';
end;

th := TMyThread.Create(true);
th.Execute
th.Free;

procedure TForm5.b1Click(Sender: TObject);
begin
  th := TMyThread.Create(true);
  th.Start;
  th.WaitFor;
end;
procedure TMyThread.Execute;
begin
    sleep(10000);
end;

type
th = class(TThread)
private
protected
  procedure Execute; Override;
public
  constructor create(createsuspended:boolean);
end;
 
constructor th.create(createsuspended: boolean);
begin
inherited Create(CreateSuspended);
FreeOnTerminate := False;
end;
 
function Ttestlib.Testy(const threads:integer): string;
var
i:integer;
thrs:th;
begin
Result:='';
for I := 0 to threads-1 do
thrs:=th.create(False);
thrs.WaitFor;
thrs.free;
Result:='Готово!';
end;

type
th = class(TThread)
private
protected
  procedure Execute; Override;
public
  constructor create(createsuspended:boolean);
end;
 
constructor th.create(createsuspended: boolean);
begin
inherited Create(CreateSuspended);
FreeOnTerminate := True;
end;
 
function Ttestlib.Testy(const threads:integer): string;
var
i:integer;
thrs:th;
begin
Result:='';
for I := 0 to threads-1 do
thrs:=th.create(False);
thrs.FreeOnTerminate:=False;
thrs.WaitFor;
thrs.Free;
Result:='Готово!';
end;