PHPUnit setMethods explained by an example

Banana.php

<?php

class Banana
{
    public function a()
    {
        return 1;
    }

    public function b()
    {
        return 2;
    }
}

$this->getMockBuilder(Banana::class)->getMock();                         // a: null, b: null
$this->getMockBuilder(Banana::class)->setMethods([])->getMock();         // a: null, b: null
$this->getMockBuilder(Banana::class)->setMethods(null)->getMock();       // a: 1,    b: 2
$this->getMockBuilder(Banana::class)->setMethods(['a'])->getMock();      // a: null, b: 2
$this->getMockBuilder(Banana::class)->setMethods(['b'])->getMock();      // a: 1,    b: null
$this->getMockBuilder(Banana::class)->setMethods(['a', 'b'])->getMock(); // a: null, b: null