testers.testEqualArrayOrMap: move argument check from bash to Nix

set -eu

preScript() {

  # If neither expectedArray nor expectedMap are declared, the test is meaningless.

  if ! isDeclaredArray expectedArray && ! isDeclaredMap expectedMap; then

    nixErrorLog "neither expectedArray nor expectedMap were set, so test is meaningless!"

    exit 1

  fi

# NOTE: If neither expectedArray nor expectedMap are declared, the test is meaningless.

# This precondition is checked in the Nix expression through an assert.

preScript() {

  if isDeclaredArray valuesArray; then

    # shellcheck disable=SC2154

    nixLog "using valuesArray: $(declare -p valuesArray)"

  stdenvNoCC,

}:

let

  inherit (lib.asserts) assertMsg;

  inherit (lib.customisation) makeOverridable;

  testEqualArrayOrMap =

      expectedMap ? null,

      script,

    }:

    assert assertMsg (

      expectedArray != null || expectedMap != null

    ) "testEqualArrayOrMap: at least one of 'expectedArray' or 'expectedMap' must be provided";

    stdenvNoCC.mkDerivation {

      __structuredAttrs = true;

      strictDeps = true;