fix. Get immutable collection with collect method.

Author: sokolovsky

src/WS/Utils/Collections/SerialStream.php

@@ -182,7 +182,7 @@ public function reverse(): Stream
      */
     public function collect(callable $collector)
     {
-        return $collector($this->getCollection());
+        return $collector($this->getCollection()->copy());
     }
 
     /**

tests/WS/Utils/Collections/ImmutableStreamTest.php

@@ -16,7 +16,8 @@ class ImmutableStreamTest extends TestCase
     /**
      * @test
      */
-    public function shouldBeImmutableInReorganizeWithCollection(): void {
+    public function shouldBeImmutableInReorganizeWithCollection(): void
+    {
         $stream = self::toCollection(1, 2, 3)
             ->stream();
 
@@ -30,4 +31,22 @@ public function shouldBeImmutableInReorganizeWithCollection(): void {
 
         self::assertThat($collection, CollectionIsEqual::to([1, 2, 3]));
     }
+
+    /**
+     * @test
+     */
+    public function shouldBeImmutableInCollectWithCollection(): void
+    {
+        $stream = self::toCollection(1, 2, 3)
+            ->stream();
+
+        $collection = $stream->getCollection();
+        $stream
+            ->collect(static function (Collection $c) {
+                $c->clear();
+                return 1;
+            });
+
+        self::assertThat($collection, CollectionIsEqual::to([1, 2, 3]));
+    }
 }