Using PHP, the most important is the testing function, i have no idea how to write this testing function in PHP please help!! thanks

Using PHP: 1. Write a function that: Given a numerical parameter in input, computes and prints all the prime numbers up to that value. Example: If input parameter is 10, output is "2,3,5,7" If input parameter is 100, output is "2,3,5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97" 2. Write a "tester function" that: Given a specific subset of inputs, tests the function described above (point 1). Example, in pseudo code: tester_function: is output from prime_function (10) equal to "2, 3, 5, 7"? If yes, test passed is output from prime_function() equal to ""? If yes, test passed