lens/docs/extensions/testing-and-publishing/testing.md

Testing Extensions

Console.log

Extension developers might find console.log() useful for printing out information and errors from extensions. To use console.log(), note that Lens is based on Electron, and that Electron has two types of processes: Main and Renderer.

Renderer Process Logs

In the Renderer process, console.log() is printed in the Console in Developer Tools (View > Toggle Developer Tools).

Main Process Logs

Viewing the logs from the Main process is a little trickier, since they cannot be printed using Developer Tools.

macOS

On macOS, view the Main process logs by running Lens from the terminal:

/Applications/Lens.app/Contents/MacOS/Lens

You can also use Console.app to view the Main process logs.

Linux

On Linux, you can access the Main process logs using the Lens PID. First get the PID:

ps aux | grep Lens | grep -v grep

Then get the Main process logs using the PID:

tail -f /proc/[pid]/fd/1 # stdout (console.log)
tail -f /proc/[pid]/fd/2 # stdout (console.error)