public function testCopyFrom()
{
$original = new VirtualPageTest_ClassA();
$original->MyInitiallyCopiedField = 'original';
$original->MyVirtualField = 'original';
$original->MyNonVirtualField = 'original';
$original->write();
$virtual = new VirtualPage();
$virtual->CopyContentFromID = $original->ID;
$virtual->write();
$virtual->copyFrom($original);
// Using getField() to avoid side effects from an overloaded __get()
$this->assertEquals('original', $virtual->getField('MyInitiallyCopiedField'), 'Fields listed in $initially_copied_fields are copied on first copyFrom() invocation');
$this->assertEquals('original', $virtual->getField('MyVirtualField'), 'Fields not listed in $initially_copied_fields are copied in copyFrom()');
$this->assertNull($virtual->getField('MyNonVirtualField'), 'Fields listed in $non_virtual_fields are not copied in copyFrom()');
$original->MyInitiallyCopiedField = 'changed';
$original->write();
$virtual->copyFrom($original);
$this->assertEquals('original', $virtual->MyInitiallyCopiedField, 'Fields listed in $initially_copied_fields are not copied on subsequent copyFrom() invocations');
}