public function testIsNull()
{
// Arrange
$a = null;
// Act
$x = __::isNull($a);
// Assert
$this->assertEquals(true, $x);
}
public function testIsNull()
{
$null1 = null;
$null2 = 'null';
$null3 = 0;
$null4 = [];
$null5 = '';
$this->assertEquals(__::isNull($null1), true);
$this->assertEquals(__::isNull($null2), false);
$this->assertEquals(__::isNull($null3), false);
$this->assertEquals(__::isNull($null4), false);
$this->assertEquals(__::isNull($null5), false);
}