# Conducting a Test Case
source: https://developer.mastercard.com/account-to-account-commerce-for-csp/tutorial/postman-ies-tutorial/step4/index.md

## Conducting a Test Case {#conducting-a-test-case}

The participant can use the test pack for two purposes:

* To execute the API and capture the request and response to develop their host
* To perform end-to-end IES testing by simulating the other participant's journey

In the section below, we will explain how to use the pack to perform end-to-end testing.

### Executing Test Scripts {#executing-test-scripts}

Before you start using the pack, make sure to select the environment from the top-right section.
![Environment](https://static.developer.mastercard.com/content/account-to-account-commerce-for-csp/uploads/Environment1-ies.png)

#### Alias Resolution Update {#alias-resolution-update}

After the request is initiated by DSP, an alias resolution request is created. The message will then be enqueued, and the outbound component will pick up the message and call CSP for alias resolution. CSP, in turn, will contact Mastercard with the alias resolution details.
![Alias Resolution Details](https://static.developer.mastercard.com/content/account-to-account-commerce-for-csp/uploads/ies-request.png)

#### How to Capture a Response {#how-to-capture-a-response}

Once you have formulated the request and clicked on **Send** , the encrypted response will be displayed in the section below:
![Capture Response](https://static.developer.mastercard.com/content/account-to-account-commerce-for-csp/uploads/Response3-ies.png)

To view the request payload, click the code label as shown below:
![Capture Request](https://static.developer.mastercard.com/content/account-to-account-commerce-for-csp/uploads/Response4-ies.png)

Validate if the status is **200 OK** and confirm the response.