QA:Testcase SwapOnZRAM stop

Description

Test stopping the swap-on-zram service temporarily.

Setup

1. A system with swap-on-zram installed and enabled.

How to test

1. Stop the swap-on-zram service:

   sudo systemctl stop swap-create@zram0.service

2. Confirm it's stopped. The service should be marked as "inactive (dead)":

   $ sudo systemctl status swap-create@zram0.service
   ● swap-create@zram0.service - Create swap on /dev/zram0
        Loaded: loaded (/usr/lib/systemd/system/swap-create@.service; static; vendor preset: disabled)
        Active: inactive (dead) since Sun 2020-06-28 19:32:07 MDT; 3s ago
          Docs: man:zram-generator(8)
                man:zram-generator.conf(5)
       Process: 646 ExecStart=/usr/lib/systemd/system-generators/zram-generator --setup-device zram0 (code=exited, status=0/SUCCESS)
       Process: 1565 ExecStop=/usr/lib/systemd/system-generators/zram-generator --reset-device zram0 (code=exited, status=0/SUCCESS)
      Main PID: 646 (code=exited, status=0/SUCCESS)
           CPU: 25ms
   
   Jun 28 19:24:57 fmac.local systemd[1]: Starting Create swap on /dev/zram0...
   Jun 28 19:24:57 fmac.local zram-generator[648]: Setting up swapspace version 1, size = 3.8 GiB (4105170944 bytes)
   Jun 28 19:24:57 fmac.local zram-generator[648]: no label, UUID=03831cdf-96df-4a7a-a6c2-3bc8406f33f3
   Jun 28 19:24:57 fmac.local systemd[1]: Finished Create swap on /dev/zram0.
   Jun 28 19:32:07 fmac.local systemd[1]: Stopping Create swap on /dev/zram0...
   Jun 28 19:32:07 fmac.local systemd[1]: swap-create@zram0.service: Succeeded.
   Jun 28 19:32:07 fmac.local systemd[1]: Stopped Create swap on /dev/zram0.
   

   zramctl should list no device:

   $ zramctl
   

   swapon should only list your disk swap partitions and no /dev/zram0 device:

   $ swapon
   NAME      TYPE       SIZE USED PRIO
   /dev/sda5 partition 10.4G   0B   -2
   

3. Start the swap-on-zram service again and confirm it's running:

   $ sudo systemctl start swap-create@zram0.service
   $ sudo systemctl status swap-create@zram0
   ● swap-create@zram0.service - Create swap on /dev/zram0
        Loaded: loaded (/usr/lib/systemd/system/swap-create@.service; static; vendor preset: disabled)
        Active: active (exited) since Sun 2020-06-28 19:32:54 MDT; 3s ago
          Docs: man:zram-generator(8)
                man:zram-generator.conf(5)
       Process: 1580 ExecStart=/usr/lib/systemd/system-generators/zram-generator --setup-device zram0 (code=exited, status=0/SUCCESS)
      Main PID: 1580 (code=exited, status=0/SUCCESS)
           CPU: 33ms
   
   Jun 28 19:32:54 fmac.local systemd[1]: Starting Create swap on /dev/zram0...
   Jun 28 19:32:54 fmac.local zram-generator[1582]: Setting up swapspace version 1, size = 3.8 GiB (4105170944 bytes)
   Jun 28 19:32:54 fmac.local zram-generator[1582]: no label, UUID=f046c6d8-3f69-4f21-81ae-a7b1555891d9
   Jun 28 19:32:54 fmac.local systemd[1]: Finished Create swap on /dev/zram0.
   

Expected Results

1. Stopping the service should work without issues and it should remove the /dev/zram0 device, i.e. it will no longer be visible in zramctl and swapon commands output.