FB eternal Access Token test user for integration tests

I have an api that calls the Facebook api.
Regarding our integration tests, it is needed to have these tests run without error when being executed given the same code, by myself or others.
We send the FB access token in the HTTP POST body from client to server, while assuming that it has been previously retrieved by the client though a client SDK.

However since access tokens for test users expire, integration tests cannot be properly automated without manually refreshing the token in our config file. When the access token expires, integration tests will always fail. Although this is ok, it is cumbersome to each time manually retrieve a new access token for achieving a successful integration test.

How can we properly solve this problem?