Improves regex reverse compilation tests

Refactors the reverse compilation tests to improve reliability and provide more informative error messages.

Specifically, it ensures that sample generation failures are handled gracefully by skipping the sample match test but still validating the recompiled regex. It also replaces direct constant access for preg errors with namespaced access.

Author: yoeunes

tests/Integration/ComprehensivePublicAPITest.php

@@ -18,7 +18,6 @@
 use RegexParser\Exception\ParserException;
 use RegexParser\ReDoS\ReDoSSeverity;
 use RegexParser\Regex;
-use RegexParser\ValidationResult;
 
 /**
  * Comprehensive test suite for the public API of RegexParser.

tests/Integration/ReverseCompilerTest.php

@@ -14,7 +14,6 @@
 namespace RegexParser\Tests\Integration;
 
 use PHPUnit\Framework\Attributes\DataProvider;
-use PHPUnit\Framework\Attributes\DoesNotPerformAssertions;
 use PHPUnit\Framework\TestCase;
 use RegexParser\NodeVisitor\CompilerNodeVisitor;
 use RegexParser\Regex;
@@ -43,15 +42,15 @@ public function test_round_trip_compilation(string $originalPattern): void
         // We suppress errors because we want to catch the false return value
         $isValid = @preg_match($recompiled, '');
 
-        if ($isValid === false) {
+        if (false === $isValid) {
             $error = preg_last_error();
             $msg = match ($error) {
-                PREG_INTERNAL_ERROR => 'PREG_INTERNAL_ERROR',
-                PREG_BACKTRACK_LIMIT_ERROR => 'PREG_BACKTRACK_LIMIT_ERROR',
-                PREG_RECURSION_LIMIT_ERROR => 'PREG_RECURSION_LIMIT_ERROR',
-                PREG_BAD_UTF8_ERROR => 'PREG_BAD_UTF8_ERROR',
-                PREG_BAD_UTF8_OFFSET_ERROR => 'PREG_BAD_UTF8_OFFSET_ERROR',
-                PREG_JIT_STACKLIMIT_ERROR => 'PREG_JIT_STACKLIMIT_ERROR',
+                \PREG_INTERNAL_ERROR => 'PREG_INTERNAL_ERROR',
+                \PREG_BACKTRACK_LIMIT_ERROR => 'PREG_BACKTRACK_LIMIT_ERROR',
+                \PREG_RECURSION_LIMIT_ERROR => 'PREG_RECURSION_LIMIT_ERROR',
+                \PREG_BAD_UTF8_ERROR => 'PREG_BAD_UTF8_ERROR',
+                \PREG_BAD_UTF8_OFFSET_ERROR => 'PREG_BAD_UTF8_OFFSET_ERROR',
+                \PREG_JIT_STACKLIMIT_ERROR => 'PREG_JIT_STACKLIMIT_ERROR',
                 default => 'Unknown Error'
             };
             $this->fail("Recompiled regex '$recompiled' from '$originalPattern' is invalid ($msg).");
@@ -63,16 +62,15 @@ public function test_round_trip_compilation(string $originalPattern): void
             // Some recursive/complex patterns might hit generator limits, so we wrap in try/catch
             $sample = $this->regexService->generate($originalPattern);
 
-            if ($sample !== '') {
-                 $this->assertMatchesRegularExpression(
-                    $recompiled,
-                    $sample,
-                    "Recompiled regex '$recompiled' failed to match sample '$sample' generated from '$originalPattern'"
-                );
-            }
+            $this->assertMatchesRegularExpression(
+                $recompiled,
+                $sample,
+                "Recompiled regex '$recompiled' failed to match sample '$sample' generated from '$originalPattern'",
+            );
         } catch (\Exception $e) {
             // If generation fails (e.g. infinite recursion), we skip the sample match test
             // but the validity test above is still valuable.
+            $this->markTestSkipped('Sample generation failed for pattern '.$originalPattern.': '.$e->getMessage());
         }
     }
 

tests/Integration/SymfonyIntegrationTest.php

@@ -15,7 +15,6 @@
 
 use PHPUnit\Framework\Attributes\DoesNotPerformAssertions;
 use PHPUnit\Framework\TestCase;
-use RegexParser\LiteralSet;
 use RegexParser\Regex;
 
 /**