# Sandbox Testing
source: https://developer.mastercard.com/mastercard-processing-authentication/documentation/sandbox-testing/index.md

## Overview {#overview}

The section describes all use cases that can be tested using the Sandbox environment. The Sandbox contains limited-capacity mock APIs, enabling you to test the APIs quickly to assist with initial integration and solution development. The Sandbox returns mock responses for a defined request. Particular values in the request body, such as path parameters or fields, will give specific predefined responses.
Note: At the beginning of each test case, there might be information (in the form of a table) that you must use in the request to execute the test case. The table displays specific values that are preconfigured in the Sandbox. Otherwise, you can send any values in the request, and the Sandbox will always return the same mock response. Warning: The current version of the Sandbox only supports inbound calls, so you will not be able to test the full authentication flow in the Sandbox. The Sandbox only supports `issCRes` calls, the API that is used during the following use cases.

|                                                  Use case                                                   | Authentication hub method |
|-------------------------------------------------------------------------------------------------------------|---------------------------|
| Authenticate a 3D-Secure Transaction with an Issuer Mobile Application                                      | `3a`                      |
| Authenticate a 3D-Secure Transaction with an Issuer Mobile Application with Alternative to OTP and Password | `3c`                      |
| Authenticate a 3D-Secure Transaction with an Issuer E-banking Service                                       | `3b`                      |