Post data to URL and include session data

In writing a test for a php script, I want to send the tested script post data and also have it receive the $_SESSION data from the sending php test script.

Peter and Burak both showed a way to send the post data in POST data to URL php One used curl and the other html5.

Using either of the two solutions, I get the $_POST data in the tested script, but not the $_SESSION data from the sending php script.

I have tried dozens of suggestions found online, but I never get the session data using those suggestions.

Help would be appreciated.