5 files changed, 140 insertions, 0 deletions
diff --git a/nixpkgs/nixos/tests/activation/etc-overlay-immutable.nix b/nixpkgs/nixos/tests/activation/etc-overlay-immutable.nix
new file mode 100644
index 000000000000..f347f9cf8efe
--- /dev/null
+++ b/nixpkgs/nixos/tests/activation/etc-overlay-immutable.nix
@@ -0,0 +1,36 @@
+{ lib, ... }: {
+
+  name = "activation-etc-overlay-immutable";
+
+  meta.maintainers = with lib.maintainers; [ nikstur ];
+
+  nodes.machine = { pkgs, ... }: {
+    system.etc.overlay.enable = true;
+    system.etc.overlay.mutable = false;
+
+    # Prerequisites
+    systemd.sysusers.enable = true;
+    users.mutableUsers = false;
+    boot.initrd.systemd.enable = true;
+    boot.kernelPackages = pkgs.linuxPackages_latest;
+
+    specialisation.new-generation.configuration = {
+      environment.etc."newgen".text = "newgen";
+    };
+  };
+
+  testScript = ''
+    with subtest("/etc is mounted as an overlay"):
+      machine.succeed("findmnt --kernel --type overlay /etc")
+
+    with subtest("switching to the same generation"):
+      machine.succeed("/run/current-system/bin/switch-to-configuration test")
+
+    with subtest("switching to a new generation"):
+      machine.fail("stat /etc/newgen")
+
+      machine.succeed("/run/current-system/specialisation/new-generation/bin/switch-to-configuration switch")
+
+      assert machine.succeed("cat /etc/newgen") == "newgen"
+  '';
+}
diff --git a/nixpkgs/nixos/tests/activation/etc-overlay-mutable.nix b/nixpkgs/nixos/tests/activation/etc-overlay-mutable.nix
new file mode 100644
index 000000000000..087c06408a71
--- /dev/null
+++ b/nixpkgs/nixos/tests/activation/etc-overlay-mutable.nix
@@ -0,0 +1,36 @@
+{ lib, ... }: {
+
+  name = "activation-etc-overlay-mutable";
+
+  meta.maintainers = with lib.maintainers; [ nikstur ];
+
+  nodes.machine = { pkgs, ... }: {
+    system.etc.overlay.enable = true;
+    system.etc.overlay.mutable = true;
+
+    # Prerequisites
+    boot.initrd.systemd.enable = true;
+    boot.kernelPackages = pkgs.linuxPackages_latest;
+
+    specialisation.new-generation.configuration = {
+      environment.etc."newgen".text = "newgen";
+    };
+  };
+
+  testScript = ''
+    with subtest("/etc is mounted as an overlay"):
+      machine.succeed("findmnt --kernel --type overlay /etc")
+
+    with subtest("switching to the same generation"):
+      machine.succeed("/run/current-system/bin/switch-to-configuration test")
+
+    with subtest("switching to a new generation"):
+      machine.fail("stat /etc/newgen")
+      machine.succeed("echo -n 'mutable' > /etc/mutable")
+
+      machine.succeed("/run/current-system/specialisation/new-generation/bin/switch-to-configuration switch")
+
+      assert machine.succeed("cat /etc/newgen") == "newgen"
+      assert machine.succeed("cat /etc/mutable") == "mutable"
+  '';
+}
diff --git a/nixpkgs/nixos/tests/activation/nix-channel.nix b/nixpkgs/nixos/tests/activation/nix-channel.nix
new file mode 100644
index 000000000000..d26ea98e56cc
--- /dev/null
+++ b/nixpkgs/nixos/tests/activation/nix-channel.nix
@@ -0,0 +1,26 @@
+{ lib, ... }:
+
+{
+
+  name = "activation-nix-channel";
+
+  meta.maintainers = with lib.maintainers; [ nikstur ];
+
+  nodes.machine = {
+    nix.channel.enable = true;
+  };
+
+  testScript = { nodes, ... }: ''
+    machine.start(allow_reboot=True)
+
+    assert machine.succeed("cat /root/.nix-channels") == "${nodes.machine.system.defaultChannel} nixos\n"
+
+    nixpkgs_unstable_channel = "https://nixos.org/channels/nixpkgs-unstable nixpkgs"
+    machine.succeed(f"echo '{nixpkgs_unstable_channel}' > /root/.nix-channels")
+
+    machine.reboot()
+
+    assert machine.succeed("cat /root/.nix-channels") == f"{nixpkgs_unstable_channel}\n"
+  '';
+
+}
diff --git a/nixpkgs/nixos/tests/activation/perlless.nix b/nixpkgs/nixos/tests/activation/perlless.nix
new file mode 100644
index 000000000000..4d784b4542f4
--- /dev/null
+++ b/nixpkgs/nixos/tests/activation/perlless.nix
@@ -0,0 +1,24 @@
+{ lib, ... }:
+
+{
+
+  name = "activation-perlless";
+
+  meta.maintainers = with lib.maintainers; [ nikstur ];
+
+  nodes.machine = { pkgs, modulesPath, ... }: {
+    imports = [ "${modulesPath}/profiles/perlless.nix" ];
+
+    boot.kernelPackages = pkgs.linuxPackages_latest;
+
+    virtualisation.mountHostNixStore = false;
+    virtualisation.useNixStoreImage = true;
+  };
+
+  testScript = ''
+    perl_store_paths = machine.succeed("ls /nix/store | grep perl || true")
+    print(perl_store_paths)
+    assert len(perl_store_paths) == 0
+  '';
+
+}
diff --git a/nixpkgs/nixos/tests/activation/var.nix b/nixpkgs/nixos/tests/activation/var.nix
new file mode 100644
index 000000000000..1a546a7671c5
--- /dev/null
+++ b/nixpkgs/nixos/tests/activation/var.nix
@@ -0,0 +1,18 @@
+{ lib, ... }:
+
+{
+
+  name = "activation-var";
+
+  meta.maintainers = with lib.maintainers; [ nikstur ];
+
+  nodes.machine = { };
+
+  testScript = ''
+    assert machine.succeed("stat -c '%a' /var/tmp") == "1777\n"
+    assert machine.succeed("stat -c '%a' /var/empty") == "555\n"
+    assert machine.succeed("stat -c '%U' /var/empty") == "root\n"
+    assert machine.succeed("stat -c '%G' /var/empty") == "root\n"
+    assert "i" in machine.succeed("lsattr -d /var/empty")
+  '';
+}