PHP Implementing Test Objects - php

Question

I'm currently creating an object in PHP that is declared on page load. The purpose of the Object is to check the connection between the client and a remote service via a function called 'checkHeartbeat'. This function will be called intermittently to see if the connection exists via AJAX.
I am trying to implement a testing parameter to alter the connection to results without querying the remote service:
fail
succeed
fail after x attempts
succeed after x attempts
The parameter is currently passed through via the URL which is picked up by the construct function of the object and placed into a variable via $_GET. Each time the checkHeartbeat function is called by AJAX it currently checks if the 'test' variable is set.
My aim is the eliminate this check on each call of checkHeartbeat however I am unsure the best method to do this. The AJAX Query will always call 'checkHeartbeat' and so I have been looking into extending/altering this function.
I attempted to re-define the object of $heartbeat within the construct to be the test object and therefore overwrite the checkHeartbeat function however this doesn't work and only returns that the connection is live. This is my re-factored code below as a demonstration of the desired outcome.
class heartbeat {
public function __construct() {
if(isset($_GET['test'])) {
$heartbeat = new testHeartbeat;
}
}
public function checkHeartbeat() {
echo 'Live connection works!';
}
}
class testHeartbeat {
public function checkHeartbeat() {
echo 'Test connection works!';
}
}
$heartbeat = new heartbeat;
$heartbeat->checkHeartbeat();
Looking into PHP objects further I have attempted to look at using Object Interfaces to define a separate function however I'm not sure how this would work and if it would still work by just calling the one function.
$heartbeat->checkHeartbeat();
My query is, what is the best method to change the 'checkHeartbeat' function to not check if the test parameter has been set on each AJAX call and only do this on the initial construct of the object. If the test parameter has been passed the checkHeartbeat will only return the test status OR will instantly make the call to the remote service if no test parameter has been set.

Answer 1

I mock this up playing around and does the work.
I am sure there is a better way, actually cleaner.
I did not found a way to modify the public variable instantiation inside the same object.
Hope this helps:
class heartbeat {
public $foo;
public function __construct()
{
$this->checkTest();
return $this->foo;
}
public function checkTest()
{
if(isset($_GET['test']))
{
$this->foo = 'true';
}
else
{
$this->foo = 'false';
}
}
public function __toString()
{
return $this->foo;
}
public function checkHeartbeat() {
echo 'Live connection works!';
}
}
class testHeartbeat {
public function checkHeartbeat() {
echo 'Test connection works!';
}
}
new heartbeat()=='true' ? $heartbeat = new testHeartbeat() : $heartbeat = new heartbeat();
$heartbeat->checkHeartbeat();
Bb!