nixpkgs/pkgs/test/kernel.nix

# to run these tests:
# nix-instantiate --eval --strict . -A tests.kernel-config
#
# make sure to use NON EXISTING kernel settings else they may conflict with
# common-config.nix
{ lib, pkgs }:

with lib;
with kernel;

let
  lts_kernel = pkgs.linuxPackages.kernel;

  # to see the result once the module transformed the lose structured config
  getConfig = structuredConfig:
    (lts_kernel.override {
      structuredExtraConfig = structuredConfig;
    }).configfile.structuredConfig;

  mandatoryVsOptionalConfig = mkMerge [
    { NIXOS_FAKE_USB_DEBUG = yes;}
    { NIXOS_FAKE_USB_DEBUG = option yes; }
  ];

  freeformConfig = mkMerge [
    { NIXOS_FAKE_MMC_BLOCK_MINORS = freeform "32"; } # same as default, won't trigger any error
    { NIXOS_FAKE_MMC_BLOCK_MINORS = freeform "64"; } # will trigger an error but the message is not great:
  ];

  yesWinsOverNoConfig = mkMerge [
    # default for "NIXOS_TEST_BOOLEAN" is no
    { "NIXOS_TEST_BOOLEAN"  = yes; } # yes wins over no by default
    { "NIXOS_TEST_BOOLEAN"  = no; }
  ];

  optionalNoWins = mkMerge [
    { NIXOS_FAKE_USB_DEBUG = option yes;}
    { NIXOS_FAKE_USB_DEBUG = yes;}
  ];

  allOptionalRemainOptional = mkMerge [
    { NIXOS_FAKE_USB_DEBUG = option yes;}
    { NIXOS_FAKE_USB_DEBUG = option yes;}
  ];

in
runTests {
  testEasy = {
    expr = (getConfig { NIXOS_FAKE_USB_DEBUG = yes;}).NIXOS_FAKE_USB_DEBUG;
    expected = { tristate = "y"; optional = false; freeform = null; };
  };

  # mandatory flag should win over optional
  testMandatoryCheck = {
    expr = (getConfig mandatoryVsOptionalConfig).NIXOS_FAKE_USB_DEBUG.optional;
    expected = false;
  };

  testYesWinsOverNo = {
    expr = (getConfig yesWinsOverNoConfig)."NIXOS_TEST_BOOLEAN".tristate;
    expected = "y";
  };

  testAllOptionalRemainOptional = {
    expr = (getConfig allOptionalRemainOptional)."NIXOS_FAKE_USB_DEBUG".optional;
    expected = true;
  };

  # check that freeform options are unique
  # Should trigger
  # > The option `settings.NIXOS_FAKE_MMC_BLOCK_MINORS.freeform' has conflicting definitions, in `<unknown-file>' and `<unknown-file>'
  testTreeform = let
    res = builtins.tryEval ( (getConfig freeformConfig).NIXOS_FAKE_MMC_BLOCK_MINORS.freeform);
  in {
    expr = res.success;
    expected = false;
  };

}