Convert DateTimeImmutable to CarbonImmutable (#5895)

* Convert DateTimeImmutable to CarbonImmutable

* add test fixture

* [ci-review] Rector Rectify

---------

Co-authored-by: Bastien Miclo <kylekatarnls@protonmail.com>
Co-authored-by: GitHub Action <actions@github.com>

rules-tests/Carbon/Rector/New_/DateTimeInstanceToCarbonRector/Fixture/include_datetime_immutable.php.inc

@@ -0,0 +1,27 @@
+<?php
+
+namespace Rector\Tests\Carbon\Rector\New_\DateTimeInstanceToCarbonRector\Fixture;
+
+final class IncludeDateTimeImmutable
+{
+    public function run()
+    {
+        $date = new \DateTimeImmutable('now');
+    }
+}
+
+?>
+-----
+<?php
+
+namespace Rector\Tests\Carbon\Rector\New_\DateTimeInstanceToCarbonRector\Fixture;
+
+final class IncludeDateTimeImmutable
+{
+    public function run()
+    {
+        $date = \Carbon\CarbonImmutable::now();
+    }
+}
+
+?>

rules/Carbon/Rector/New_/DateTimeInstanceToCarbonRector.php

@@ -4,6 +4,7 @@
 
 namespace Rector\Carbon\Rector\New_;
 
+use PhpParser\Node\Expr\MethodCall;
 use PhpParser\Node;
 use PhpParser\Node\Expr\New_;
 use PhpParser\Node\Expr\StaticCall;
@@ -56,22 +57,32 @@ public function getNodeTypes(): array
      */
     public function refactor(Node $node): ?Node
     {
-        if (! $this->isName($node->class, 'DateTime')) {
-            return null;
+        if ($this->isName($node->class, 'DateTime')) {
+            return $this->refactorWithClass($node, 'Carbon\\Carbon');
+        }
+
+        if ($this->isName($node->class, 'DateTimeImmutable')) {
+            return $this->refactorWithClass($node, 'Carbon\\CarbonImmutable');
         }
 
-        if ($node->isFirstClassCallable()) {
+        return null;
+    }
+
+    public function refactorWithClass(New_ $new, string $className): MethodCall|StaticCall|null
+    {
+        if ($new->isFirstClassCallable()) {
             return null;
         }
 
         // no arg? ::now()
-        $carbonFullyQualified = new FullyQualified('Carbon\Carbon');
-        if ($node->args === []) {
+        $carbonFullyQualified = new FullyQualified($className);
+
+        if ($new->args === []) {
             return new StaticCall($carbonFullyQualified, new Identifier('now'));
         }
 
-        if (count($node->getArgs()) === 1) {
-            $firstArg = $node->getArgs()[0];
+        if (count($new->getArgs()) === 1) {
+            $firstArg = $new->getArgs()[0];
 
             if ($firstArg->value instanceof String_) {
                 return $this->carbonCallFactory->createFromDateTimeString($carbonFullyQualified, $firstArg->value);