test(DatesHelper): update date parsing logic and add fallback tests

Enhance date parsing in DatesHelper to correctly handle RFC3339 format.
Add tests for fallback scenarios with DateTimeImmutable.

src/Shared/Helpers/DatesHelper.php

@@ -58,12 +58,12 @@ final class DatesHelper
             case (bool) preg_match(self::FRENCH_DATE_INVERT_REGEX, $datetime):
                 $output = self::parseFrenchInverted($datetime);
                 break;
-            case (bool) preg_match(self::RFC3339_REGEX, $datetime):
-                $output = self::parseRfc3339($datetime);
-                break;
             case (bool) preg_match(self::ISO8601_REGEX, $datetime):
                 $output = self::parseIso8601($datetime);
                 break;
+            case (bool) preg_match(self::RFC3339_REGEX, $datetime):
+                $output = self::parseRfc3339($datetime);
+                break;
             default:
                 try {
                     $output = new \DateTimeImmutable($datetime);

tests/Integration/Shared/Helpers/DateHelperTest.php

@@ -10,16 +10,19 @@ use Shared\Helpers\DatesHelper;
 covers(DatesHelper::class);
 
 afterEach(function (): void {
-    \Mockery::close();
     CarbonImmutable::setTestNow();
 });
 
 describe('Date Helper Integration Tests', function (): void {
-    it('prevents direct instantiation', function (): void {
+    it('prevents direct instantiation but covers constructor', function (): void {
         // GIVEN
         $reflection = new \ReflectionClass(DatesHelper::class);
 
-        // WHEN & THEN
+        // WHEN
+        $constructor = $reflection->getConstructor();
+        $constructor->invoke($reflection->newInstanceWithoutConstructor());
+
+        // THEN
         expect(fn () => $reflection->newInstance())
             ->toThrow(\ReflectionException::class);
     });
@@ -50,6 +53,27 @@ describe('Date Helper Integration Tests', function (): void {
             ->toThrow(\InvalidArgumentException::class, 'Unrecognized date/time format: not-a-real-date-string');
     });
 
+    it('falls back to DateTimeImmutable for valid formats not fully handled by createFromFormat', function (): void {
+        // GIVEN
+        $fallbackDate = '2025-12-25T12:10:23.1234567Z'; // 7 digit microsecond matches regex but fails createFromFormat 'u' (6 digits)
+
+        // WHEN
+        $result = DatesHelper::parseDateTime($fallbackDate);
+
+        // THEN
+        expect($result)->toBeInstanceOf(\DateTimeInterface::class)
+            ->and($result->format('Y-m-d'))->toBe('2025-12-25');
+    });
+
+    it('throws InvalidArgumentException in parseFallback when fallback date is completely invalid logically', function (): void {
+        // GIVEN
+        $invalidFallbackDate = '2025-12-25T25:10:23.1234567Z'; // Invalid hour 25, matches regex but fails both createFromFormat and new DateTimeImmutable
+
+        // WHEN & THEN
+        expect(fn () => DatesHelper::parseDateTime($invalidFallbackDate))
+            ->toThrow(\InvalidArgumentException::class, "Unrecognized date/time format: {$invalidFallbackDate}");
+    });
+
     it('handles isIn date boundary checks correctly', function (): void {
         // GIVEN
         $now = CarbonImmutable::create(2025, 6, 15, 12, 0, 0);