let
  cmp = a: b:
    let
      ord1 = builtins.compareVersions a b;
      ord2 = builtins.compareVersions b a;
    in
      assert ord1 == -ord2; ord1;
in

[
  (cmp "1.2.3" "1.2.3")
  (cmp "1.2.2" "1.2.3")
  (cmp "1.2.3" "1.2.40")
  (cmp "1.2.3" ".1.2.3")
  (cmp "1.2.3" "1..2.3")
  (cmp "1.2.3" "1.2.3.")
  (cmp "1.2.3" "1.2")
  (cmp "1.2.3" "1.2.a")
  (cmp "1a.b" "1a.2")
  (cmp "1" "")
  (cmp "1.0" "1.0.0")
  (cmp "2.3" "2.3pre")
  (cmp "2.3" "2.3.0pre")
  (cmp "2.3pre" "2.3.0pre")
  (cmp "2.3" "2.3prepre")
  (cmp "2.3pre" "2.3prepre")
  (cmp "2.3prepre" "2.3prepre")
  # Subset of test cases from eval-okay-versions.nix shipped by C++ Nix
  (cmp "1.0" "2.3")
  (cmp "2.1" "2.3")
  (cmp "2.3" "2.3")
  (cmp "2.5" "2.3")
  (cmp "3.1" "2.3")
  (cmp "2.3.1" "2.3")
  (cmp "2.3.1" "2.3a")
  (cmp "2.3pre1" "2.3")
  (cmp "2.3pre3" "2.3pre12")
  (cmp "2.3a" "2.3c")
  (cmp "2.3pre1" "2.3c")
  (cmp "2.3pre1" "2.3q")
]