如何创建一个usort函数php来列出一个比较数组的数组

Question

I am still learning php I would like to discover how can I create a function compare and list using usort() for this array and debug render for phpunit?

// create an array with names to be sorted
$names = array('a', 'b', 'c');

// render the sorted names
$example = new \Example($names);
$example->renderNamesSorted();

function sortedNames (){

}
function renderNamesSorted (){

}

My actual output on php unit is

Failed asserting that two arrays are equal.
Array (
     0 => 'a'
-    1 => 'b'
-    2 => 'c'
+    1 => 'c'
+    2 => 'b'
 )

I would like create a function to compare and avoid not equal value in output phpunit

Any ideas? thanks