Expand tests and API code.

app/Repositories/PiggyBank/PiggyBankRepositoryInterface.php

@@ -102,6 +102,15 @@ interface PiggyBankRepositoryInterface
      */
     public function find(int $piggyBankid): PiggyBank;
 
+    /**
+     * Find by name or return NULL.
+     *
+     * @param string $name
+     *
+     * @return PiggyBank|null
+     */
+    public function findByName(string $name): ?PiggyBank;
+
     /**
      * Get current amount saved in piggy bank.
      *