public function testInvert()
{
$arr = array('row1' => array('col1' => 'val1', 'col2' => 'val2'), 'row2' => array('col1' => 'val3', 'col2' => 'val4'));
$this->assertEquals(ArrayLib::invert($arr), array('col1' => array('row1' => 'val1', 'row2' => 'val3'), 'col2' => array('row1' => 'val2', 'row2' => 'val4')));
}