nix-helpers: 420d2570aaaf4b13fb40dc6d140d569a197128a4

     1: # Add a value somewhere inside a nested set of attributes, based on a path
     2: { dummyWithEnv, lib }:
     3: with builtins;
     4: with lib;
     5: with rec {
     6:   # The actual function
     7:   go = { path, value, set }:
     8:     with rec {
     9:       name = head path;
    10:       new = if length path == 1 then
    11:         value
    12:       else
    13:         go {
    14:           inherit value;
    15:           path = (tail path);
    16:           set = set."${name}" or { };
    17:         };
    18:     };
    19:     set // {
    20:       "${name}" = new;
    21:     };
    22: 
    23:   # Unit test
    24:   testData = rec {
    25:     inputPath = [ "x" "y" "z" ];
    26:     inputValue = 1337;
    27:     inputSet = {
    28:       a = {
    29:         b = 1;
    30:         c = null;
    31:       };
    32:       b = [ "foo" "bar" ];
    33:       x = {
    34:         a = 1;
    35:         y = {
    36:           a = 42;
    37:           b = null;
    38:         };
    39:       };
    40:     };
    41: 
    42:     expected = {
    43:       a = {
    44:         b = 1;
    45:         c = null;
    46:       };
    47:       b = [ "foo" "bar" ];
    48:       x = {
    49:         a = 1;
    50:         y = {
    51:           a = 42;
    52:           b = null;
    53:           z = 1337;
    54:         };
    55:       };
    56:     };
    57: 
    58:     got = go {
    59:       path = inputPath;
    60:       value = inputValue;
    61:       set = inputSet;
    62:     };
    63:     message = "'got' should match 'expected'";
    64:     result = got == expected;
    65:   };
    66: 
    67:   test = testData.result || abort (toJSON testData);
    68: };
    69: assert test;
    70: go