# Invoking an API using Insomnia
source: https://developer.mastercard.com/account-to-account-commerce-for-csp/tutorial/insomnia-ies/step_5/index.md

Make sure the Environment IES_ACCREDITATION_TEST_ENVIRONMENT_Sandbox is chosen before executing the APIs.

## Run the Test Case {#run-the-test-case}

1. Choose the Sandbox configuration for the **IES Accreditation Test Environment**.

2. Open the folder named **TC-0_AR_RETRIEVE_CSP_List**.

3. Click on **Get CSP List** and then click "Send."
   ![runthetestcase](https://static.developer.mastercard.com/content/account-to-account-commerce-for-csp/uploads/insomniaslides/iesrunthetestcase1.png)

4. The response will appear on the right-hand side of the page. Validate if the status is 200 OK.