refactor list vaults

src/main/java/PasswordManager.java

@@ -38,6 +38,9 @@ public class PasswordManager implements PasswordManagerInterface {
     @Override
     public void listVaults() {
         println("Vaults:");
+        for (int i = 0; i < vaults.size(); i++) {
+            println("- vault id: " + i);
+        }
     }
 
     public void createNewVault() {

src/test/java/PasswordManagerTest.java

@@ -46,7 +46,8 @@ class PasswordManagerTest {
         pm.inputStream = new ByteArrayInputStream("l\n".getBytes(StandardCharsets.UTF_8));
         pm.outputStream = outputStream;
         pm.showMenu();
-        assertTrue(outputStream.toString().endsWith("Vaults:\n"));
+        pm.createNewVault();
+        assertTrue(outputStream.toString().contains("Vaults:\n- vault id: 0\n"));
     }
 
     @Test