to run the author tests you will need a .json file that describes the
config as so:

    /path/to/working/business-truelayer > cat business-truelayer-credentials.json
    {
        "application_name" : "your_test_application_name",
        "client_id" : "your_client_id"",
        "client_secret" : "your_client_secret"",
        "host" : "truelayer-sandbox.com",
        "api_host" : "api.truelayer-sandbox.com",
        "auth_host" : "auth.truelayer-sandbox.com",
        "kid" : "your_kid"",
        "private_key" : "/path/to/working/business-truelayer/your-ec512-private-key.pem"
    }

you will need to update the various values as defined by your sandbox
setup, and create yourself a private and public key (see TrueLayer's)
docs for that

having created that you can run:

    TRUELAYER_CREDENTIALS=business-truelayer-credentials.json prove -lr xt/
