Fix 'Error: Public Key required' when running flutterwave-node-v3 tests

The flutterwave-node-v3 test suite fails at startup with Error: Public Key required from rave.base, before any test runs. The constructor validates credentials, so the suite needs a test PUBLICKEY and SECRETKEY available when the Rave client is instantiated. Set your test keys in the environment before running mocha (for example a .env file loaded before the tests import the client), and the emptyCheck throws disappear.

The test suite blew up with Error: Public Key required because no test credentials were configured. Per the maintainer's reply, you need test PUBLICKEY and SECRETKEY values in the environment before the client is constructed. I set mine in a .env loaded at the top of the test setup and npm test started running. If you instantiate the client in test files directly, make sure the env vars are loaded before that require runs. Source: https://github.com/Flutterwave/Node-v3/issues/13

Source: https://github.com/Flutterwave/Node-v3/issues/13