如何使用phpunit自动模拟类中的类？

I have a class structure like this:

class A {
    public someFunction() {
        $objectB = new B();
        $result = $objectB->getResult();
        return $result;
    }
}

I am writing the unit test for someFunction() that belongs to class A. However, it depends on class B. I can mock someFunction() but how can I resolve the dependency on class B? I want to mock class B automatically.

Use dependency injection: either provide a method to set the B object, or pass the b object optionally to someFunction().

Original code

class A {
    public function someFunction() {
        $objectB = new B();
        $result = $objectB->getResult();
        return $result;
    }
}

Optional parameter

class A {
    public function someFunction($objectB = null) {
        if ($objectB == null) { $objectB = new B(); }
        $result = $objectB->getResult();
        return $result;
    }
}

Setter method

class A {
    protected $b;


    public function __construct() {
        $this->b = new B();
    }

    public function setB($b) {
        $this->b = $b;
    }

    public function someFunction() {
        $result = $this->b->getResult();
        return $result;
    }
}

Another possibility for dependency injection is to refactor to an "init" method, i.e.:

class A
{
    function setB ( B $b = null )
    {
        $this->b = ( !is_null($b) ? $b
            $this->initB()
        );
    }

    function initB ( )
    {
       return new B();
    }

    function someMethod ( )
    {
        return $this->b->getResult();
    }
}

With this implementation, subclasses of "A" can override "initB" to change the dependency and a mock of A generated with "PHPUnit_Framework_TestCase::getMock()" can define a canned return value for the method without relying on the functionality of the setter (or you can omit the setter).