[12.x] Let Collection collect() method accept key to collect

src/Illuminate/Collections/Enumerable.php

@@ -1243,9 +1243,10 @@ public function zip($items);
     /**
      * Collect the values into a collection.
      *
+     * @param  string|null  $key
      * @return \Illuminate\Support\Collection<TKey, TValue>
      */
-    public function collect();
+    public function collect($key);
 
     /**
      * Get the collection of items as a plain array.

src/Illuminate/Collections/Traits/EnumeratesValues.php

@@ -926,11 +926,12 @@ public function uniqueStrict($key = null)
     /**
      * Collect the values into a collection.
      *
+     * @param  string|null  $key
      * @return \Illuminate\Support\Collection<TKey, TValue>
      */
-    public function collect()
+    public function collect($key = null)
     {
-        return new Collection($this->all());
+        return new Collection($key ? $this->get($key) : $this->all());
     }
 
     /**

tests/Support/SupportCollectionTest.php

@@ -5471,6 +5471,23 @@ public function testCollect($collection)
             'b' => 2,
             'c' => 3,
         ], $data->all());
+
+        $data = $collection::make([
+            'foos' => [
+                'foo',
+                'bar',
+                'baz',
+            ],
+            'a' => 1,
+        ])->collect('foos');
+
+        $this->assertInstanceOf(Collection::class, $data);
+
+        $this->assertSame([
+            'foo',
+            'bar',
+            'baz',
+        ], $data->all());
     }
 
     #[DataProvider('collectionClassProvider')]