override getQualifiedForeignKeyName() and add tests for whereBelongsTo

Author: Hikmat Hasanov

src/Relations/BelongsTo.php

@@ -72,4 +72,12 @@ protected function whereInMethod(EloquentModel $model, $key)
     {
         return 'whereIn';
     }
+
+    /**
+     * @return string
+     */
+    public function getQualifiedForeignKeyName()
+    {
+        return $this->foreignKey;
+    }
 }

tests/RelationsTest.php

@@ -534,4 +534,17 @@ public function testDoubleSaveManyToMany(): void
         $this->assertEquals([$user->_id], $client->user_ids);
         $this->assertEquals([$client->_id], $user->client_ids);
     }
+
+    public function testWhereBelongsTo()
+    {
+        $user = User::create(['name' => 'John Doe']);
+        Item::create(['user_id' => $user->_id]);
+        Item::create(['user_id' => $user->_id]);
+        Item::create(['user_id' => $user->_id]);
+        Item::create(['user_id' => null]);
+
+        $items = Item::query()->whereBelongsTo($user)->get();
+
+        $this->assertCount(3, $items);
+    }
 }