add a section on testing flow for getting valid session tokens

docs/testing/overview.mdx

@@ -24,4 +24,15 @@ Once retrieved, include the token value in the `__clerk_testing_token` query par
 POST https://happy-hippo-1.clerk.accounts.dev/v1/client/sign_ups?__clerk_testing_token=1713877200-c_2J2MvPu9PnXcuhbPZNao0LOXqK9A7YrnBn0HmIWxy
 ```
 
+## Test flow for getting a valid session token
+
+When writing tests using Clerk, if you need to get a valid session token, you can use the following flow:
+
+1. If you have not already, [create a new user](https://clerk.com/docs/reference/backend-api/tag/Users#operation/CreateUser).
+2. [Create a new session](https://clerk.com/docs/reference/backend-api/tag/Sessions#operation/createSession) for the user.
+3. [Create a session token](https://clerk.com/docs/reference/backend-api/tag/Sessions#operation/CreateSessionToken) using the session ID returned in the previous step.
+4. Pass the returned session token as the value of an Authorization header to any other requests you're making, as such: `Authorization: Bearer <session_token>`.
+
+Note that Clerk's session tokens are short-lived and are valid only for 60 seconds (learn more about why this is the case in [our "how clerk works" guide](/docs/how-clerk-works-overview)), if the session token expires, you will need to refresh it with the same [create session token endpoint](https://clerk.com/docs/reference/backend-api/tag/Sessions#operation/CreateSessionToken). The most common ways to do this are to either hit this endpoint before every test to ensure you have a valid session token, or to run an interval timer that refreshes the token before it expires.
+
 For more information, feedback or issues, visit the [`@clerk/testing`](https://github.com/clerk/javascript/tree/main/packages/testing) package.