[8.x] Handle cursor paginator when no items are found (#42963)

* handle cursor paginator when no items are found

* StyleCI suugested fix

Author: rodrigopedra

src/Illuminate/Pagination/AbstractCursorPaginator.php

@@ -155,6 +155,10 @@ public function previousCursor()
             return null;
         }
 
+        if ($this->items->isEmpty()) {
+            return null;
+        }
+
         return $this->getCursorForItem($this->items->first(), false);
     }
 
@@ -170,6 +174,10 @@ public function nextCursor()
             return null;
         }
 
+        if ($this->items->isEmpty()) {
+            return null;
+        }
+
         return $this->getCursorForItem($this->items->last(), true);
     }
 

tests/Pagination/CursorPaginatorTest.php

@@ -4,6 +4,7 @@
 
 use Illuminate\Pagination\Cursor;
 use Illuminate\Pagination\CursorPaginator;
+use Illuminate\Support\Collection;
 use PHPUnit\Framework\TestCase;
 
 class CursorPaginatorTest extends TestCase
@@ -76,6 +77,26 @@ public function testCanTransformPaginatorItems()
         $this->assertSame([['id' => 6], ['id' => 7]], $p->items());
     }
 
+    public function testReturnEmptyCursorWhenItemsAreEmpty()
+    {
+        $cursor = new Cursor(['id' => 25], true);
+
+        $p = new CursorPaginator(Collection::make(), 25, $cursor, [
+            'path' => 'http://website.com/test',
+            'cursorName' => 'cursor',
+            'parameters' => ['id'],
+        ]);
+
+        $this->assertInstanceOf(CursorPaginator::class, $p);
+        $this->assertSame([
+            'data' => [],
+            'path' => 'http://website.com/test',
+            'per_page' => 25,
+            'next_page_url' => null,
+            'prev_page_url' => null,
+        ], $p->toArray());
+    }
+
     protected function getCursor($params, $isNext = true)
     {
         return (new Cursor($params, $isNext))->encode();