Adding tests for inverter API

[aryanbhosale]

Add Tests for Inverter API (for #106 and #109 )

Detailed Description

The proposed change is to add tests for the inverter API, specifically for the Enphase and SolarEdge inverters. The tests should cover the different functionalities such as getting site coordinates, list of sites, and inverter data.

Context

Adding tests for the inverter API is crucial to ensure the correctness and reliability of the code. It will help catch any regressions or issues early in the development process and provide confidence in the functionality of the API.

Possible Implementation

One possible implementation could be to create a separate test suite for the inverter API that mocks the APIs for Enphase and SolarEdge.

For the Enphase inverter, tests could be added to verify the correct generation of access tokens, fetching of site coordinates, and retrieval of inverter data using the OAuth 2.0 authentication.

For the SolarEdge inverter, tests could be added to verify the correct handling of authentication keys (SOLAREDGE_ACCOUNT_KEY and SOLAREDGE_USER_KEY), fetching of site coordinates and site lists, and retrieval of inverter data.

[aryanbhosale]

Hi @peterdudfield , does this look good?