1. Follow the Google Chat app quickstart for Apps Script https://developers.google.com/workspace/chat/quickstart/apps-script-app and open the resulting Apps Script project in a web browser.

2. Override the Apps Script project contents with the files appsscript.json, AppAuthenticationUtils.gs, and Main.gs from this code sample directory.

3. To run samples that use app credentials:

   1. Create a service account. For steps, see Authenticate as a Google Chat app.

   2. Open AppAuthenticationUtils.gs and set the value of the constant SERVICE_ACCOUNT to the private key's JSON of the service account that you created in the previous step.

In the Main.gs file, each function contains a sample that calls a Chat API method using either app or user authentication. To run one of the samples, select the name of the function from the dropdown menu and click Run.