QA:Testcase partitioning webui guided btrfs preserve home

Associated release criterion
This test case is associated with the Fedora_42_Beta_Release_Criteria#Custom_partitioning release criterion. If you are doing release validation testing, a failure of this test case may be a breach of that release criterion. If so, please file a bug and nominate it as blocking the appropriate milestone, using the blocker bug nomination page.

Description

This test case ensures that re-installing to the storage devices from an existing Fedora install and preserving the /home device works and does not delete data, when using the webui-based installer.

Setup

1. Prepare a test system with a working, supported storage device of sufficient size for a Fedora install, and a Fedora installation medium that uses the webui-based installer - e.g. Fedora Workstation live, on Fedora 42 and above.
2. Install Fedora 41 or 42 from any Edition or Spin which uses Btrfs filesystem by default. Ensure a separate /home subvolume is created. If you are installing to at least 50 GB of free space, this will happen if you use Automatic storage configuration during disk partitioning; otherwise, you will have to use custom partitioning and ensure a separate /home subvolume is created.
3. On the installed system, create some distinct files and directories in your home directory or directly in /home.

How to test

1. Boot the webui-based installer using any available means, e.g. Fedora Workstation live on Fedora 42+.
2. Proceed to the installer's "Installation method" screen, making sensible choices.
3. Ensure the target device you prepared is selected as the "Destination".
4. Ensure the "Mount point assignment" option is selected, and click "Next".
5. Assign all existing devices to the appropriate mount points - that is, assign the /boot mount point to the existing /boot device, the /home mount point to the existing /home device, the / mount point to the existing root device, and so on.
6. Ensure that Reformat is not checked for /home, but is checked for all other devices.
7. Complete the installation process, making sensible selections for all other installer options.
8. Boot the installed system.
9. After logging in, check that your home directory or /home contains the files you created on your previous system (check their contents as well).

Expected Results

1. The expected partition layout should be created on the target device(s).
2. The install process should complete successfully and the installed system should boot as expected.
3. The partitions and subvolumes which were assigned some mountpoints in the installer should be mounted. Any partitions or subvolumes which weren't assigned any mountpoints shouldn't be mounted.
4. Your personal files on your /home partition must be intact.