Challenge 1 — Solution

Task: Write a class StringHelper with a method reverse(string $s):
string (using strrev()) and a method isPalindrome(string $s): bool.
Write a PHPUnit test class with at least three test methods covering: a
normal reverse, a true palindrome case, and a false (non-palindrome)
case.

---- src/StringHelper.php ----

<?php
class StringHelper {
    public function reverse(string $s): string {
        return strrev($s);
    }

    public function isPalindrome(string $s): bool {
        return $s === $this->reverse($s);
    }
}

---- tests/StringHelperTest.php ----

<?php
use PHPUnit\Framework\TestCase;

class StringHelperTest extends TestCase {
    public function testReverseReturnsReversedString() {
        $helper = new StringHelper();
        $result = $helper->reverse("hello");
        $this->assertEquals("olleh", $result);
    }

    public function testIsPalindromeReturnsTrueForPalindrome() {
        $helper = new StringHelper();
        $result = $helper->isPalindrome("racecar");
        $this->assertTrue($result);
    }

    public function testIsPalindromeReturnsFalseForNonPalindrome() {
        $helper = new StringHelper();
        $result = $helper->isPalindrome("hello");
        $this->assertFalse($result);
    }
}


Expected test run output:
PHPUnit 10.x

...                                                                 3 / 3 (100%)

OK (3 tests, 3 assertions)

Notes:
- reverse() is a thin wrapper around PHP's own built-in strrev()
  function, exactly as the task specified - no custom reversal logic
  needed.
- isPalindrome() reuses reverse() internally rather than duplicating
  reversal logic, then compares the reversed string against the
  original with strict equality (===) - a string is a palindrome
  exactly when it reads the same forwards and backwards.
- The three tests deliberately cover three genuinely different code
  paths: a plain reverse operation, a true palindrome, and a false
  (non-palindrome) result - assertTrue()/assertFalse() are used
  specifically since isPalindrome() returns a real boolean, matching
  the chapter's own guidance on choosing the right assertion for the
  value being checked.