home-manager/tests/lib/generators/mkImpureConfigMerger.nix

# Tests for the activation snippet generated by mkImpureConfigMerger. It is
# run the way home activation runs it: as a script with the home-manager bash
# helpers available, against files in a temporary home.
{
  lib,
  pkgs,
  ...
}:

let
  mkMerger =
    format: static:
    lib.hm.generators.mkImpureConfigMerger {
      inherit pkgs format;
      empty = "{}";
      # The trailing comment must not break the filter the operation is
      # embedded in.
      jqOperation = "$dynamic * $static # recursive merge";
      path = "/@TMPDIR@/hm-user/.config/testmerger/settings.${format}";
      staticSettings = builtins.toFile "static-settings.${format}" static;
    };

  # Mirror the activation script environment: set -euo pipefail is active and
  # home-manager.sh provides errorEcho.
  mkScript =
    name: snippet:
    pkgs.writeScript name ''
      set -euo pipefail
      errorEcho() { echo "$*" >&2; }
      ${snippet}
    '';

  mergeJson = mkScript "merge-json" (mkMerger "json" (builtins.toJSON { nixManaged = true; }));
  mergeToml = mkScript "merge-toml" (mkMerger "toml" "nixManaged = true\n");

  # Messages must print the path literally instead of evaluating it.
  mergeOddPath = mkScript "merge-odd-path" (
    lib.hm.generators.mkImpureConfigMerger {
      inherit pkgs;
      format = "json";
      empty = "{}";
      jqOperation = "$dynamic * $static";
      path = "/@TMPDIR@/hm-user/odd $(touch marker)/settings.json";
      staticSettings = builtins.toFile "static-settings.json" "{}";
    }
  );

  largeStatic = builtins.toJSON { nixManaged = lib.genList (i: i) 40000; };
  largeStaticFile = builtins.toFile "static-settings.json" largeStatic;
  mergeLargeStatic = mkScript "merge-large-static" (mkMerger "json" largeStatic);

  # jaq prints the first object of this stream before failing on the
  # truncated second one, so checking only the reader output would accept a
  # partial read.
  truncatedJson = builtins.toFile "truncated.json" ''
    {"keep":true}
    {"lost":
  '';

  userToml = builtins.toFile "user.toml" ''
    userSetting = 5
  '';

  expectedJson = builtins.toFile "expected.json" ''
    {
      "nixManaged": true
    }
  '';

  expectedToml = builtins.toFile "expected.toml" ''
    nixManaged = true
  '';

  expectedUserToml = builtins.toFile "expected-user.toml" ''
    userSetting = 5
    nixManaged = true
  '';

  mergeYaml = mkScript "merge-yaml" (
    mkMerger "yaml" ''
      managed:
        key: nix
    ''
  );

  userYaml = builtins.toFile "user.yaml" ''
    user:
      theme: dark
      recent:
        - /a
        - /b
  '';

  expectedYaml = builtins.toFile "expected.yaml" ''
    ---
    user:
      theme: dark
      recent:
        - /a
        - /b
    managed:
      key: nix
    ...
  '';

  userDateToml = builtins.toFile "user-date.toml" ''
    # Keep this file intact when jaq cannot parse its date value.
    date = 1979-05-27T07:32:00Z
    userSetting = 5
  '';
in
{
  nmt.script = ''
    substitute ${mergeJson} $TMPDIR/merge-json --subst-var TMPDIR
    substitute ${mergeToml} $TMPDIR/merge-toml --subst-var TMPDIR
    substitute ${mergeLargeStatic} $TMPDIR/merge-large-static --subst-var TMPDIR
    chmod +x $TMPDIR/merge-json $TMPDIR/merge-toml $TMPDIR/merge-large-static

    mkdir -p $TMPDIR/hm-user/.config/testmerger
    jsonSettings=$TMPDIR/hm-user/.config/testmerger/settings.json
    tomlSettings=$TMPDIR/hm-user/.config/testmerger/settings.toml

    # A reader that emits JSON before failing must fail activation and keep
    # the original file instead of merging the partial output.
    cat ${truncatedJson} > $jsonSettings
    if $TMPDIR/merge-json > /dev/null 2>&1; then
      fail "Merging a truncated JSON stream must fail activation"
    fi
    assertFileContent $jsonSettings ${truncatedJson}

    printf '%s\n' '{"a":1}' '{"b":2}' > $jsonSettings
    cp $jsonSettings $TMPDIR/original.json
    if $TMPDIR/merge-json > /dev/null 2> $TMPDIR/merge-error; then
      fail "Merging multiple JSON values must fail activation"
    fi
    assertFileContent $jsonSettings $TMPDIR/original.json
    grep -qF "$jsonSettings" $TMPDIR/merge-error \
      || fail "A failed merge must name the config file"

    ${lib.getExe pkgs.jaq} -cn '{userSetting: [range(0; 40000)]}' > $jsonSettings
    if [ "$(wc -c < $jsonSettings)" -le 131072 ]; then
      fail "The existing JSON file must exceed 128 KiB"
    fi
    $TMPDIR/merge-json
    ${lib.getExe pkgs.jaq} -e '.userSetting == [range(0; 40000)] and .nixManaged == true' $jsonSettings > /dev/null

    if [ "$(wc -c < ${largeStaticFile})" -le 131072 ]; then
      fail "The Nix-declared JSON settings must exceed 128 KiB"
    fi
    echo '{"userSetting":true}' > $jsonSettings
    $TMPDIR/merge-large-static
    ${lib.getExe pkgs.jaq} -e '.userSetting == true and .nixManaged == [range(0; 40000)]' $jsonSettings > /dev/null

    substitute ${mergeOddPath} $TMPDIR/merge-odd-path --subst-var TMPDIR
    chmod +x $TMPDIR/merge-odd-path
    oddSettings='/'"$TMPDIR"'/hm-user/odd $(touch marker)/settings.json'
    DRY_RUN=1 $TMPDIR/merge-odd-path > $TMPDIR/odd-output
    mkdir -p "$(dirname "$oddSettings")"
    echo '{' > "$oddSettings"
    if $TMPDIR/merge-odd-path 2>> $TMPDIR/odd-output; then
      fail "Merging a malformed file must fail activation"
    fi
    [[ ! -e marker ]] || fail "Messages must not run commands in the path"
    grep -qF 'odd $(touch marker)/settings.json' $TMPDIR/odd-output \
      || fail "Messages must contain the literal path"

    # A missing JSON target installs the generated settings.
    rm -f $jsonSettings
    $TMPDIR/merge-json
    assertFileContent $jsonSettings ${expectedJson}

    # A missing TOML target installs the generated settings instead of
    # failing on a file seeded with the JSON `empty` value.
    $TMPDIR/merge-toml
    assertFileContent $tomlSettings ${expectedToml}

    # Existing user settings survive the merge.
    cat ${userToml} > $tomlSettings
    $TMPDIR/merge-toml
    assertFileContent $tomlSettings ${expectedUserToml}

    # A zero-byte file is treated as `empty`.
    : > $tomlSettings
    $TMPDIR/merge-toml
    assertFileContent $tomlSettings ${expectedToml}

    # jaq 3.1.1 cannot parse TOML dates. If a newer jaq can, they would pass
    # through JSON as strings and come back as TOML strings, so this failing
    # means the documented limitation needs revisiting.
    cat ${userDateToml} > $tomlSettings
    if $TMPDIR/merge-toml > /dev/null 2>&1; then
      fail "Merging TOML with a date value must fail activation"
    fi
    assertFileContent $tomlSettings ${userDateToml}

    substitute ${mergeYaml} $TMPDIR/merge-yaml --subst-var TMPDIR
    chmod +x $TMPDIR/merge-yaml
    yamlSettings=$TMPDIR/hm-user/.config/testmerger/settings.yaml

    # YAML is written in block style, and merging the written file again
    # leaves it unchanged.
    cat ${userYaml} > $yamlSettings
    $TMPDIR/merge-yaml
    assertFileContent $yamlSettings ${expectedYaml}
    $TMPDIR/merge-yaml
    assertFileContent $yamlSettings ${expectedYaml}
  '';
}