Pavucontrol — Adding and Removing Devices on-the-fly

This test case tests that devices can be added and removed on-the-fly and that audio is correctly routed through these devices or ports.

Setup

This test case can be performed on bare-metal machines.
The computer must be equipped with a sound device with multiple ports (speakers and phones), such as laptops or desktops with back and front audio outputs.
You should have an external sound device at your disposal (USB, Firewire)
Install a desktop version of Fedora 34 (or later).
Install the pavucontrol package.
Perform the following steps as a regular user.

Start Pavucontrol and check that it starts.
Start some sound playing application and play some audio. Confirm that the audio is audible through the speakers.
Use the volume slider to adjust the volume to a certain level (Output page).
Plug the headphones and check that the output switches to headphones and stops being played over the speakers.
Use the volume slider to adjust the volume to a certain level (Output page).
Unplug the headphones and check that the output returns back to built-in speakers.
Check that the volume level is the same as you have set in Step 3.
If you have an HDMI or DisplayPort monitor with speakers, connect it and check that the device appears in the Pavucontrol’s list of devices. Change the output of the playback to be routed to this device on the Playback tab. Confirm that the sound is played over this device.
If you have performed Step 8, unplug the HDMI/DP monitor and check that the device disappears from the device list and that the sound plays on the default sound device again and that the volume level has not changed from the level set in Step 3.
Connect the external sound device and make sure it appears in the Output Devices.
If it does not become the default device, make it a default device and confirm that sound is routed through it.
Disconnect the external device and make sure it disappears from the list of devices and the sound starts playing through one of the available devices.

Pavucontrol starts and shows the available sound devices on the Output devices tab.
Plugging additional sound device makes them default and the sound output is rerouted to them.
Unplugging additional sound devices removes them from the list and returns the sound to be played on the original device.
The volume level is maintained separately for each of the devices and it should always be restored to the last known state when a device is used.