{ lib, config, pkgs, ... }:

{
  users.knownGroups = [ "foo" "created.group" "deleted.group" ];
  users.groups.foo.gid = 42000;
  users.groups.foo.description = "Foo group";
  users.groups.foo.members = [ "admin" "foo" ];

  users.groups."created.group".gid = 42001;
  users.groups."unknown.group".gid = 42002;

  users.knownUsers = [ "foo" "created.user" "deleted.user" ];
  users.users.foo.uid = 42000;
  users.users.foo.gid = 42000;
  users.users.foo.description = "Foo user";
  users.users.foo.isHidden = false;
  users.users.foo.home = "/Users/foo";
  users.users.foo.createHome = true;
  users.users.foo.shell = pkgs.bashInteractive;

  users.users."created.user".uid = 42001;
  users.users."created.user".description = null;
  users.users."created.user".home = null;
  users.users."created.user".shell = null;

  users.users."unknown.user".uid = 42002;

  test = ''
    set -v

    # checking group creation in /activate
    grep "dscl . -create ${lib.escapeShellArg "/Groups/foo"} PrimaryGroupID 42000" ${config.out}/activate
    grep "dscl . -create ${lib.escapeShellArg "/Groups/foo"} RealName ${lib.escapeShellArg "Foo group"}" ${config.out}/activate
    grep "dscl . -create ${lib.escapeShellArg "/Groups/created.group"} PrimaryGroupID 42001" ${config.out}/activate
    (! grep "dscl . -delete ${lib.escapeShellArg "/Groups/created.group"}" ${config.out}/activate)

    # checking group deletion in /activate
    grep "dscl . -delete ${lib.escapeShellArg "/Groups/deleted.group"}" ${config.out}/activate
    (! grep "dscl . -create ${lib.escapeShellArg "/Groups/deleted.group"}" ${config.out}/activate)

    echo "checking group membership in /activate" >&2
    grep "dscl . -create ${lib.escapeShellArg "/Groups/foo"} GroupMembership ${lib.escapeShellArgs [ "admin" "foo" ]}" ${config.out}/activate
    grep "dscl . -create ${lib.escapeShellArg "/Groups/created.group"} GroupMembership" ${config.out}/activate

    # checking unknown group in /activate
    # checking groups not in knownGroups don't appear in /activate
    (! grep "dscl . -create ${lib.escapeShellArg "/Groups/unknown.group"}" ${config.out}/activate)
    (! grep "dscl . -delete ${lib.escapeShellArg "/Groups/unknown.group"}" ${config.out}/activate)

    # checking user creation in /activate
    grep "sysadminctl -addUser ${lib.escapeShellArgs [ "foo" "-UID" 42000 "-GID" 42000 "-fullName" "Foo user" "-home" "/Users/foo" "-shell" "/run/current-system/sw/bin/bash" ]}" ${config.out}/activate
    grep "createhomedir -cu ${lib.escapeShellArg "foo"}" ${config.out}/activate
    grep "sysadminctl -addUser ${lib.escapeShellArgs [ "created.user" "-UID" 42001 ]} .* ${lib.escapeShellArgs [ "-shell" "/usr/bin/false" ] }" ${config.out}/activate
    grep "sysadminctl -addUser ${lib.escapeShellArg "created.user"} .* ${lib.escapeShellArgs [ "-home" "/var/empty" ]}" ${config.out}/activate
    (! grep "dscl . -delete ${lib.escapeShellArg "/Users/created.user"}" ${config.out}/activate)
    (! grep "dscl . -delete ${lib.escapeShellArg "/Groups/created.user"}" ${config.out}/activate)

    # checking user properties always get updated in /activate
    grep "dscl . -create ${lib.escapeShellArg "/Users/foo"} PrimaryGroupID 42000" ${config.out}/activate
    grep "dscl . -create ${lib.escapeShellArg "/Users/foo"} RealName ${lib.escapeShellArg "Foo user"}" ${config.out}/activate
    grep "createhomedir -cu ${lib.escapeShellArg "foo"}" ${config.out}/activate
    grep "dscl . -create ${lib.escapeShellArg "/Users/foo"} UserShell ${lib.escapeShellArg "/run/current-system/sw/bin/bash"}" ${config.out}/activate
    grep "dscl . -create ${lib.escapeShellArg "/Users/foo"} IsHidden 0" ${config.out}/activate

    # checking user properties that are null don't get updated in /activate
    (! grep "dscl . -create ${lib.escapeShellArg "/Users/created.user"} RealName" ${config.out}/activate)
    (! grep "dscl . -create ${lib.escapeShellArg "/Users/created.user"} UserShell" ${config.out}/activate)

    # checking user deletion in /activate
    grep "dscl . -delete ${lib.escapeShellArg "/Users/deleted.user"}" ${config.out}/activate
    (! grep "sysadminctl -addUser ${lib.escapeShellArg "deleted.user"}" ${config.out}/activate)

    # checking that users not specified in knownUsers doesn't get changed in /activate
    (! grep "sysadminctl -addUser ${lib.escapeShellArg "unknown.user"}" ${config.out}/activate)
    (! grep "dscl . -delete ${lib.escapeShellArg "/Users/unknown.user"}" ${config.out}/activate)
    (! grep "dscl . -create ${lib.escapeShellArg "/Users/unknown.user"}" ${config.out}/activate)

    set +v
  '';
}