Add tests suite for the Webhook sender package

[koladev32]

To ensure our sender package is reliable and robust, we need to implement a comprehensive suite of unit tests. Specifically, the focus will be on the SendWebhook function, as well as any auxiliary functions it calls.

Scope:

1. Test marshalJSON:

   • Ensure correct JSON marshaling with valid data structures.
   • Test with invalid structures and ensure that errors are correctly returned.

2. Test prepareRequest:

   • Ensure the request is correctly prepared with the given URL, JSON bytes, and secret hash.
   • Confirm headers (like Content-Type and X-Secret-Hash) are appropriately set.

3. Test sendRequest:

   • Mock different scenarios including:
     • Successful responses.
     • Client Errors (e.g., HTTP 400).
     • Server Errors (e.g., HTTP 500).
   • Ensure errors are returned as expected.

4. Test closeResponse:

   • Verify that the response body is correctly closed.
   • Ensure that any errors during the closure are handled appropriately.

5. Test processResponse:

   • Check that the function correctly determines the status based on various mocked response codes and bodies.
   • Ensure the function returns the response body and any potential errors.

6. Test Overall Flow in SendWebhook:

   • Successful webhook sending.
   • Failed webhook due to request preparation errors.
   • Failed webhook due to marshaling errors.
   • Failed webhook due to response processing errors.
   • Logging on failed webhook delivery (checking the invocation of WebhookLogger).