MyClass.php

<?php

class MyClass
{
    private $condition1;
    private $condition2;

    public function __construct($condition1, $condition2)
    {
        $this->condition1 = $condition1;
        $this->condition2 = $condition2;
    }

    public function doSomething()
    {
        if ($this->condition1) {
            $this->executeOption1();
        }

        if ($this->condition2) {
            $this->executeOption2();
        }

        return $result;
    }
}

MyClassTest.php

<?php

class MyClassTest extends PHPUnit_Framework_TestCase
{
    public function testCondition1()
    {
        $object = new MyClass(true, false);

        $this->assertOption1Executed($object);
    }

    public function testCondition2()
    {
        $object = new MyClass(false, true);

        $this->assertOption2Executed($object);
    }
}