public function testSinglePolicy()
 {
     $p = new MySociety\TheyWorkForYou\Policies();
     $this->assertEquals(count($p->getArray()), 74);
     $p = $p->limitToSet('health');
     $this->assertEquals(count($p->getArray()), 4);
     $p = new MySociety\TheyWorkForYou\Policies();
     $p = $p->limitToSet('education');
     $this->assertEquals(count($p->getArray()), 5);
     $p = new MySociety\TheyWorkForYou\Policies(363);
     $this->assertEquals(count($p->getArray()), 1);
     $p = $p->limitToSet('health');
     $this->assertEquals(count($p->getArray()), 1);
     $p = new MySociety\TheyWorkForYou\Policies(363);
     $p = $p->limitToSet('education');
     $this->assertEquals(count($p->getArray()), 0);
 }