---
title: "Test the Application"
url: https://docs.catalyst.zoho.com/en/tutorials/alien-city/java/test-application/
description: "Create a single-page serverless web application using Catalyst Advanced I/O Function and Catalyst Data Store that allows you to report or look up alien encounters in a city."
last_updated: 2026-08-17T12:16:04Z
service: All Services
type: tutorial
related_links:
  - name: "Serve CLI Resources"
    url: /en/cli/v1/serve-resources/introduction/
---

# Test the Application

Before you deploy the application to the remote console, you can [test the application](https://docs.catalyst.zoho.com/en/cli/v1/serve-resources/introduction/) on a local server and check if everything works fine using the Catalyst CLI. 

To serve the Catalyst project locally, execute the following command from your project directory:

```sh
catalyst serve
```

This Alien City application is now served at default port 3000. The local endpoint URLs of the components are displayed.

> **Note:** Every time you access the home page or any of the sub-pages of your client, or the function, the CLI will display a live log of the URL accessed, along with the HTTP request method.

![catalyst_alcity_serve](https://catalyst-docs-development.zohostratus.in/images/tutorials/alcity/catalyst_alcity_serve.webp)

You can now open the client component’s local URL in a browser to access the Alien City application.

![catalyst_alien_city_catalyst_serve](https://catalyst-docs-development.zohostratus.in/images/tutorials/alcity/catalyst_alien_city_catalyst_serve.webp)

Let’s test the application by entering a city’s name and checking for the history of an alien encounter in the city. Since we have not reported an alien encounter in a city yet, the result should be negative. 

Enter a city name in the text box and click **Check**.

![catalyst_alien_city_new_york](https://catalyst-docs-development.zohostratus.in/images/tutorials/alcity/catalyst_alien_city_new_york.webp)

Since a matching record for this city is not found in the Data Store, the client displays a negative response.

![catalyst_alien_city_new_york_no_alien](https://catalyst-docs-development.zohostratus.in/images/tutorials/alcity/catalyst_alien_city_new_york_no_alien.webp)

Now, let’s report an alien encounter. Click the *Report Alien Encounter* tab. Enter a city name and click **Report**. We have entered "**Amsterdam**" in our application.

![catalyst_alien_city_report_encoutner](https://catalyst-docs-development.zohostratus.in/images/tutorials/alcity/catalyst_alien_city_report_encoutner.webp)

The application will display a pop-up box confirming that the data is added to the Data Store.

![catalyst_alien_city_local_host_message](https://catalyst-docs-development.zohostratus.in/images/tutorials/alcity/catalyst_alien_city_local_host_message.webp)

You can verify this by opening your Catalyst console and navigating to **Data Store** under *Storage* **>** *CloudScale*. Click the **Data View** tab to view the record that was just inserted.

![catalyst_alien_city_data_view](https://catalyst-docs-development.zohostratus.in/images/tutorials/alcity/catalyst_alien_city_data_view.webp)

Next, let's search for this city in the client and check if it fetches this record from the Data Store. Click *Check My City* in the client application and enter the name of the city that you just reported. Here, we enter "**Amsterdam**". Click **Check**.

![catalyst_alien_city_report_created](https://catalyst-docs-development.zohostratus.in/images/tutorials/alcity/catalyst_alien_city_report_created.webp)

The client displays a positive response.

You can also check if the client displays the duplication message by reporting the same city again.

![catalyst_alien_ctiy_local_repeat_report](https://catalyst-docs-development.zohostratus.in/images/tutorials/alcity/catalyst_alien_ctiy_local_repeat_report.webp)

If this setup is working correctly, we can deploy the application to production.