{
  pkgs,
  pkgsLinux,
  buildPackages,
  lib,
  callPackage,
  runCommand,
  stdenv,
  substituteAll,
  testers,
}:
# Documentation is in doc/builders/testers.chapter.md
{
  # See https://nixos.org/manual/nixpkgs/unstable/#tester-testBuildFailure
  # or doc/builders/testers.chapter.md
  testBuildFailure =
    drv:
    drv.overrideAttrs (orig: {
      builder = buildPackages.bash;
      args =
        [
          (substituteAll {
            coreutils = buildPackages.coreutils;
            src = ./expect-failure.sh;
          })
          orig.realBuilder or stdenv.shell
        ]
        ++ orig.args or [
          "-e"
          (orig.builder or ../../stdenv/generic/default-builder.sh)
        ];
    });

  # See https://nixos.org/manual/nixpkgs/unstable/#tester-testEqualDerivation
  # or doc/builders/testers.chapter.md
  testEqualDerivation = callPackage ./test-equal-derivation.nix { };

  # See https://nixos.org/manual/nixpkgs/unstable/#tester-testEqualContents
  # or doc/builders/testers.chapter.md
  testEqualContents =
    {
      assertion,
      actual,
      expected,
    }:
    runCommand "equal-contents-${lib.strings.toLower assertion}" { inherit assertion actual expected; }
      ''
        echo "Checking:"
        echo "$assertion"
        if ! diff -U5 -r "$actual" "$expected" --color=always
        then
          echo
          echo 'Contents must be equal, but were not!'
          echo
          echo "+: expected,   at $expected"
          echo "-: unexpected, at $actual"
          exit 1
        else
          find "$expected" -type f -executable > expected-executables | sort
          find "$actual" -type f -executable > actual-executables | sort
          if ! diff -U0 actual-executables expected-executables --color=always
          then
            echo
            echo "Contents must be equal, but some files' executable bits don't match"
            echo
            echo "+: make this file executable in the actual contents"
            echo "-: make this file non-executable in the actual contents"
            exit 1
          else
            echo "expected $expected and actual $actual match."
            echo 'OK'
            touch $out
          fi
        fi
      '';

  # See https://nixos.org/manual/nixpkgs/unstable/#tester-testVersion
  # or doc/builders/testers.chapter.md
  testVersion =
    {
      package,
      command ? "${package.meta.mainProgram or package.pname or package.name} --version",
      version ? package.version,
    }:
    runCommand "${package.name}-test-version"
      {
        nativeBuildInputs = [ package ];
        meta.timeout = 60;
      }
      ''
        if output=$(${command} 2>&1); then
          if grep -Fw -- "${version}" - <<< "$output"; then
            touch $out
          else
            echo "Version string '${version}' not found!" >&2
            echo "The output was:" >&2
            echo "$output" >&2
            exit 1
          fi
        else
          echo -n ${lib.escapeShellArg command} >&2
          echo " returned a non-zero exit code." >&2
          echo "$output" >&2
          exit 1
        fi
      '';

  # See doc/builders/testers.chapter.md or
  # https://nixos.org/manual/nixpkgs/unstable/#tester-invalidateFetcherByDrvHash
  invalidateFetcherByDrvHash =
    f: args:
    let
      drvPath = (f args).drvPath;
      # It's safe to discard the context, because we don't access the path.
      salt = builtins.unsafeDiscardStringContext (lib.substring 0 12 (baseNameOf drvPath));
      # New derivation incorporating the original drv hash in the name
      salted = f (args // { name = "${args.name or "source"}-salted-${salt}"; });
      # Make sure we did change the derivation. If the fetcher ignores `name`,
      # `invalidateFetcherByDrvHash` doesn't work.
      checked =
        if salted.drvPath == drvPath then
          throw "invalidateFetcherByDrvHash: Adding the derivation hash to the fixed-output derivation name had no effect. Make sure the fetcher's name argument ends up in the derivation name. Otherwise, the fetcher will not be re-run when its implementation changes. This is important for testing."
        else
          salted;
    in
    checked;

  # See doc/builders/testers.chapter.md or
  # https://nixos.org/manual/nixpkgs/unstable/#tester-runNixOSTest
  runNixOSTest =
    let
      nixos = import ../../../nixos/lib { inherit lib; };
    in
    testModule:
    nixos.runTest {
      _file = "pkgs.runNixOSTest implementation";
      imports = [
        (lib.setDefaultModuleLocation "the argument that was passed to pkgs.runNixOSTest" testModule)
      ];
      hostPkgs = pkgs;
      node.pkgs = pkgsLinux;
    };

  # See doc/builders/testers.chapter.md or
  # https://nixos.org/manual/nixpkgs/unstable/#tester-invalidateFetcherByDrvHash
  nixosTest =
    let
      /*
        The nixos/lib/testing-python.nix module, preapplied with arguments that
        make sense for this evaluation of Nixpkgs.
      */
      nixosTesting = (
        import ../../../nixos/lib/testing-python.nix {
          inherit (stdenv.hostPlatform) system;
          inherit pkgs;
          extraConfigurations = [
            (
              { lib, ... }:
              {
                config.nixpkgs.pkgs = lib.mkDefault pkgsLinux;
              }
            )
          ];
        }
      );
    in
    test:
    let
      loadedTest = if builtins.typeOf test == "path" then import test else test;
      calledTest = lib.toFunction loadedTest pkgs;
    in
    nixosTesting.simpleTest calledTest;

  hasPkgConfigModule =
    { moduleName, ... }@args:
    lib.warn
      "testers.hasPkgConfigModule has been deprecated in favor of testers.hasPkgConfigModules. It accepts a list of strings via the moduleNames argument instead of a single moduleName."
      (
        testers.hasPkgConfigModules (
          builtins.removeAttrs args [ "moduleName" ] // { moduleNames = [ moduleName ]; }
        )
      );
  hasPkgConfigModules = callPackage ./hasPkgConfigModules/tester.nix { };

  testMetaPkgConfig = callPackage ./testMetaPkgConfig/tester.nix { };
}