bug #29794 Always pass $key to NullAdapter->createCacheItem (TysonAndre)

This PR was merged into the 4.2 branch.

Discussion
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Always pass $key to NullAdapter->createCacheItem

| Q             | A
| ------------- | ---
| Branch?       | 4.2
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes (build failure seems unrelated)
| Fixed tickets |
| License       | MIT
| Doc PR        |

Previously, if this were called, it would throw an ArgumentCountError.
I'm assuming existing code always checks hasItem, so this bug hasn't impacted many people.
This was noticed via static analysis.

The get() method was added to NullAdapter in symfony 4.2

Commits
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1976d29 Always pass $key to NullAdapter->createCacheItem

src/Symfony/Component/Cache/Adapter/NullAdapter.php

@@ -42,7 +42,7 @@ function ($key) {
      */
     public function get(string $key, callable $callback, float $beta = null, array &$metadata = null)
     {
-        return $callback(($this->createCacheItem)());
+        return $callback(($this->createCacheItem)($key));
     }
 
     /**

src/Symfony/Component/Cache/Tests/Adapter/NullAdapterTest.php

@@ -34,6 +34,19 @@ public function testGetItem()
         $this->assertNull($item->get(), "Item's value must be null when isHit is false.");
     }
 
+    public function testGet()
+    {
+        $adapter = $this->createCachePool();
+
+        $fetched = [];
+        $item = $adapter->get('myKey', function ($item) use (&$fetched) { $fetched[] = $item; });
+        $this->assertCount(1, $fetched);
+        $item = $fetched[0];
+        $this->assertFalse($item->isHit());
+        $this->assertNull($item->get(), "Item's value must be null when isHit is false.");
+        $this->assertSame('myKey', $item->getKey());
+    }
+
     public function testHasItem()
     {
         $this->assertFalse($this->createCachePool()->hasItem('key'));