---
title: "Test the Application"
url: https://docs.catalyst.zoho.com/en/tutorials/alien-city-appsail/python/test-app/
description: "Create an application and host it on Catalyst using the Catalyst AppSail service 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 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 `3001`.

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

![catalyst_alien_city_cli_appsail_py_serve](https://catalyst-docs-development.zohostratus.in/images/tutorials/alien-city-appsail-express/catalyst_alien_city_cli_appsail_py_serve.webp)

You can now open the application's localhost URL in a browser to access the Alien City application.
![catalyst_alcity_catalyst_test_1](https://catalyst-docs-development.zohostratus.in/images/tutorials/alien-city-appsail-express/catalyst_alcity_catalyst_test_1.webp)

Let’s test the application by entering a city’s name and checking for the history of an alien encounter in the city. Because 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_alcity_catalyst_test_2](https://catalyst-docs-development.zohostratus.in/images/tutorials/alien-city-appsail-express/catalyst_alcity_catalyst_test_2.webp)

A matching record for this city will not be found in the Data Store, and the application displays a negative response.
![catalyst_alcity_catalyst_test_3](https://catalyst-docs-development.zohostratus.in/images/tutorials/alien-city-appsail-express/catalyst_alcity_catalyst_test_3.webp)

Now, let’s report an alien encounter. Click the **Report Alien Encounter** tab. Enter a city name and click **Report**. We have entered "**Monaco**" in our application.
![catalyst_alcity_catalyst_test_4](https://catalyst-docs-development.zohostratus.in/images/tutorials/alien-city-appsail-express/catalyst_alcity_catalyst_test_4.webp)

The application will display a pop-up box confirming that the data has been added to the Data Store.
![catalyst_alcity_catalyst_test_5](https://catalyst-docs-development.zohostratus.in/images/tutorials/alien-city-appsail-express/catalyst_alcity_catalyst_test_5.webp)

You can verify this by opening your Catalyst console and navigating to **Data Store** under *CloudScale*. Click the **Data View** tab of the table to view the record that was just inserted.
![catalyst_alcity_catalyst_test_6](https://catalyst-docs-development.zohostratus.in/images/tutorials/alien-city-appsail-express/catalyst_alcity_catalyst_test_6.webp)

Next, let’s search for this city in the application and check if it fetches this record from the Data Store. Click the **Check My City** tab in the application and enter the name of the city that you just reported. Here, we enter "**Monaco**." Click **Check**.
![catalyst_alcity_catalyst_test_7](https://catalyst-docs-development.zohostratus.in/images/tutorials/alien-city-appsail-express/catalyst_alcity_catalyst_test_7.webp)

The application displays a positive response.

You can also check if the application displays the duplication message by reporting the same city again.
![catalyst_alcity_catalyst_test_8](https://catalyst-docs-development.zohostratus.in/images/tutorials/alien-city-appsail-express/catalyst_alcity_catalyst_test_8.webp)

If this setup is working correctly, you can deploy the application.