public function testNullRelationIsNotQueriedManyTimes()
 {
     $this->loadData('bookshop');
     $book = Book::selectPrimaryKey($this->getConn(), 50);
     $this->resetQueryCount();
     $this->assertNull($book->details);
     //make sure null has been saved and not queried for again
     $book->details;
     $book->details;
     $book->details;
     $this->assertSame(1, $this->getQueryCount());
 }