How to mock a protected property on an object (assume for class Baz, Baz#foo uses Baz::$bar which needs to be mocked)

bar.php

<?php

class Bar
{
  public function getSomething() 
  {
    return 'something';
  }
}

baz.php

<?php

class Baz
{
 protected $bar;
 
 public function getBar() 
 {
   if (!$this->bar) {
     $this->bar = new Bar();
   }
   return $this->bar;
 }
 
 public function setBar(Bar $bar) 
 {
   $this->bar = $bar;
   return $this;
 }
 
 public function foo() 
 {
   return $this->getBar()->getSomething();
 }
}

getter.php

<?php

//via a getter method on Baz 
function testFoo()
{
  $barMock = $this->getMock('Bar');
  $barMock->expects($this->once())->method('getSomething')->will($this->returnValue('something'));
  
  $baz = $this->getMockBuilder('Baz')->setMethods(array('getBar'))->getMock();
  $baz->expects($this->once())->method('getBar')->will($this->returnValue($barMock));
  
  $baz->foo();
}

reflection.php

<?php

//via reflection 
function testFoo()
{
  $barMock = $this->getMock('Bar');
  $barMock->expects($this->once())->method('getSomething')->will($this->returnValue('something'));
  
  $baz     = new Baz();
  
  $ref     = new ReflectionClass($baz);
  $barRef  = $ref->getProperty('bar');
  $barRef->setAccessible(true);
  $barRef->setValue($baz, $barMock);
  
  $baz->foo();
}

setter.php

<?php

//via a setter method on Baz 
function testFoo()
{
  $barMock = $this->getMock('Bar');
  $barMock->expects($this->once())->method('getSomething')->will($this->returnValue('something'));
  
  $baz = new Baz();
  $baz->setBar($barMock);
  
  $baz->foo();
}