Local Database Functionality Test

**Objective:**
Make sure the local database works well whether the internet is on or off, and that it saves and sends all sensor data reliably.

**Action:**
1. **Check Local Database Functionality Offline:**
- Make sure the database saves sensor datа if there's no internet.
- Ensure no data is lost when the internet is down.

2. **Test Sending Data to MQTT Broker When Internet is Back:**
- Make sure all saved data in the local database is sent to the MQTT broker once the internet is back.
- Ensure no data is left behind during this process.

3. **Add a Detailed Test in [testing.py](http://testing.py/):**
- Include a test in [testing.py](http://testing.py/) to check how well the local database works.
- Check if the app can connect to the local database.
- Confirm the presence of tables with sensor data in the database.
- Count the number of data rows in each table.