[Feature Request]: Generate JSON Test Cases for Metrics module

[beesaferoot]

Preflight Checklist

• I have read the Contributing Guidelines for this project, if it exists.
• I agree to follow the Code of Conduct that this project adheres to.
• I have searched the issue tracker for a feature request that matches the one I want to file, without success.

Problem Description

Based on the comment on this PR

It would be nice to be able to verify metrics generation with tests with JSON sample data.

i.e Having a list of sample metrics.

[
 {
   "serial_number":"A111222",
   "timestamp":1611583070,
   "data":{
      "token_count":13,
      "tampered":false,
      "firmware_version":"1.14.2"
   },
   "historical_data":[
      {
         "timestamp":1611583070,
         "panel_voltage":17.5,
         "battery_voltage":12.5,
         "panel_current":2.2,
         "battery_current":3.2
      },
      {
         "timestamp":1611583010,
         "panel_voltage":15.7,
         "battery_voltage":12.6,
         "panel_current":2.2,
         "battery_current":3.2,
         "usb_load_1_current":0.7
      }
   ],
   "data_format":{
      "variables":{
         "battery_current":{
            "name":"Battery Current",
            "type":"float",
            "unit":"A",
            "description":"The battery current, negative means it is charging."
         }
      }
   }
}
]

Proposed Solution

Get already generated metrics data as JSON i.e sample_metrics.json

Resources:

• https://github.com/openpaygo/metrics/blob/main/Specifications.md

Alternatives Considered

No alternative considered

Additional Information

No response