diff --git a/pkgs/development/compilers/elm/packages/elm-test-rs/default.nix b/pkgs/development/compilers/elm/packages/elm-test-rs/default.nix
index c0b8f07b2838..691a66c17ace 100644
--- a/pkgs/development/compilers/elm/packages/elm-test-rs/default.nix
+++ b/pkgs/development/compilers/elm/packages/elm-test-rs/default.nix
@@ -2,18 +2,57 @@
   lib,
   rustPlatform,
   fetchFromGitHub,
+  fetchzip,
   openssl,
   stdenv,
+  nodejs,
+  elmPackages,
+  writableTmpDirAsHomeHook,
+  runCommand,
 }:
+let
+  # provide an elm dependencies cache and registry for all the test case projects
+  # see update.sh for how it is created
+  elmDeps = builtins.fromJSON (builtins.readFile ./elm-srcs.json);
 
-rustPlatform.buildRustPackage rec {
+  setupDepsCache = lib.concatMapStrings (
+    dep:
+    let
+      dep_src = fetchzip {
+        pname = "${dep.author}_${dep.package}";
+        inherit (dep) sha256 version;
+        url = "https://github.com/${dep.author}/${dep.package}/archive/${dep.version}.tar.gz";
+      };
+    in
+    ''
+      dep_dir=$pkgs_dir/${dep.author}/${dep.package}/${dep.version}
+      mkdir -p $dep_dir
+      cp -r ${dep_src}/. $dep_dir
+    ''
+  ) elmDeps;
+
+  elm-deps =
+    runCommand "elm-deps"
+      {
+        buildInputs = [ ];
+      }
+      ''
+        pkgs_dir=$out/${elmPackages.elm.version}/packages
+
+        mkdir -p $pkgs_dir
+        cp ${./registry.dat} $pkgs_dir/registry.dat
+
+        ${setupDepsCache}
+      '';
+in
+rustPlatform.buildRustPackage (finalAttrs: {
   pname = "elm-test-rs";
   version = "3.2.0";
 
   src = fetchFromGitHub {
     owner = "mpizenberg";
     repo = "elm-test-rs";
-    tag = "v${version}";
+    tag = "v${finalAttrs.version}";
     hash = "sha256-RP0VTYMrQ8I/Szi1TFcYHmWpdDh1F1jAhWDYlYVoqyM=";
   };
 
@@ -21,8 +60,20 @@ rustPlatform.buildRustPackage rec {
 
   cargoHash = "sha256-BrWN4rXTFHXj5aDvdn55ThSAF+NqMbUg7LnQcrapI0U=";
 
-  # Tests perform networking and therefore can't work in sandbox
-  doCheck = false;
+  nativeCheckInputs = [
+    nodejs
+    elmPackages.elm
+    writableTmpDirAsHomeHook
+  ];
+
+  # use the default ELM_HOME location to avoid more troubles
+  preCheck = ''
+    mkdir -p $HOME/.elm
+    cp -r --no-preserve=mode ${finalAttrs.passthru.elm-deps}/. $HOME/.elm
+  '';
+
+  passthru.elm-deps = elm-deps;
+  passthru.updateScript = ./update.sh;
 
   meta = {
     description = "Fast and portable executable to run your Elm tests";
@@ -35,4 +86,4 @@ rustPlatform.buildRustPackage rec {
       turbomack
     ];
   };
-}
+})
diff --git a/pkgs/development/compilers/elm/packages/elm-test-rs/elm-srcs.json b/pkgs/development/compilers/elm/packages/elm-test-rs/elm-srcs.json
new file mode 100644
index 000000000000..5e023ac3ae53
--- /dev/null
+++ b/pkgs/development/compilers/elm/packages/elm-test-rs/elm-srcs.json
@@ -0,0 +1,92 @@
+[
+  {
+    "author": "elm",
+    "package": "browser",
+    "version": "1.0.2",
+    "sha256": "0863nw2hhbpm3s03lm1imi5x28wwknzrwg2p79s5mydgvdvgwjf0"
+  },
+  {
+    "author": "elm",
+    "package": "bytes",
+    "version": "1.0.8",
+    "sha256": "0n411j2cyz9m241q6vszfzpq3fraradwal5m0gigp2505mdfpz3x"
+  },
+  {
+    "author": "elm",
+    "package": "core",
+    "version": "1.0.5",
+    "sha256": "0g3xbi8f9k5q45s95nx3jfvzwdf4b2n63a52wr4027d2xjx0pmvl"
+  },
+  {
+    "author": "elm",
+    "package": "html",
+    "version": "1.0.0",
+    "sha256": "15k1679ja57vvlpinpv06znmrxy09lbhzfkzdc89i01qa8c4gb4a"
+  },
+  {
+    "author": "elm",
+    "package": "html",
+    "version": "1.0.1",
+    "sha256": "1m045b6cixyqygll4cjf9d9s3k1lj839kxc3gbid0fpqc4g10i6b"
+  },
+  {
+    "author": "elm",
+    "package": "json",
+    "version": "1.1.3",
+    "sha256": "1hx986yqw1v2bpkrh6brszl8n8awwg1s8zi7v5qg0p1rqwvjlicz"
+  },
+  {
+    "author": "elm",
+    "package": "json",
+    "version": "1.1.4",
+    "sha256": "0niq7id7r78ckvgap4psq0xdlnhcv1dz2j81lrnhl4fsgn0awvs8"
+  },
+  {
+    "author": "elm",
+    "package": "random",
+    "version": "1.0.0",
+    "sha256": "0z0znkwfs35xiabk6pa9yqwsq03jssgd7jmsj1kk000mikfm7f39"
+  },
+  {
+    "author": "elm",
+    "package": "time",
+    "version": "1.0.0",
+    "sha256": "0wqa2vhl1zf8z0j2yd3yjwfhr0dydfns43bbzll3k4rhnjadxr1l"
+  },
+  {
+    "author": "elm",
+    "package": "url",
+    "version": "1.0.0",
+    "sha256": "1f2ij4i7zmijnj2i50qf19lpkr14bhms8dkq029inb5mydi9f8gs"
+  },
+  {
+    "author": "elm",
+    "package": "virtual-dom",
+    "version": "1.0.2",
+    "sha256": "1d6pqv6cvrsk2cp3dxxrq82vwrij4hrgjazg3lh93z75jkpvywhl"
+  },
+  {
+    "author": "elm",
+    "package": "virtual-dom",
+    "version": "1.0.5",
+    "sha256": "16v6h8msm1yin45vwdj8g0wnqs4gjjyknhz2iamrzzbssxvryyqv"
+  },
+  {
+    "author": "elm-explorations",
+    "package": "test",
+    "version": "2.0.0",
+    "sha256": "1gfgafc25brvsa3cw3s3xjrlqhfx66x0hrym0haxrah45s10fq4a"
+  },
+  {
+    "author": "elm-explorations",
+    "package": "test",
+    "version": "2.2.1",
+    "sha256": "0rgwwqbnbj61x0c3lvk9d0z2qlw219djkhnc02qygsw9k5599q3v"
+  },
+  {
+    "author": "mpizenberg",
+    "package": "elm-test-runner",
+    "version": "6.0.1",
+    "sha256": "1b0fypnjj3hhs08yvdi77kf2vfzdy1ril4dxl5xnzp8rgnxbxf1r"
+  }
+]
diff --git a/pkgs/development/compilers/elm/packages/elm-test-rs/registry.dat b/pkgs/development/compilers/elm/packages/elm-test-rs/registry.dat
new file mode 100644
index 000000000000..53921fc91132
Binary files /dev/null and b/pkgs/development/compilers/elm/packages/elm-test-rs/registry.dat differ
diff --git a/pkgs/development/compilers/elm/packages/elm-test-rs/update.sh b/pkgs/development/compilers/elm/packages/elm-test-rs/update.sh
new file mode 100755
index 000000000000..dbdda64c510c
--- /dev/null
+++ b/pkgs/development/compilers/elm/packages/elm-test-rs/update.sh
@@ -0,0 +1,117 @@
+#!/usr/bin/env nix-shell
+#! nix-shell -i bash -p nix-update nodejs elmPackages.elm jq nix gitMinimal
+
+set -euo pipefail
+
+# shows time before each line, to help expose slow steps
+export PS4='+ $(date "+%H:%M:%S") '
+
+NIXPKGS_DIR="$(git rev-parse --show-toplevel)"
+PACKAGE_DIR="$(realpath "$(dirname "$0")")"
+
+# with this, it works by directly calling this script
+UPDATE_NIX_ATTR_PATH="${UPDATE_NIX_ATTR_PATH:-elmPackages.elm-test-rs}"
+ELM_VERSION=$(nix-instantiate --eval -A elmPackages.elm.version $NIXPKGS_DIR --raw)
+
+nix-update "$UPDATE_NIX_ATTR_PATH"
+SRC_DIR="$(nix-build -A "${UPDATE_NIX_ATTR_PATH}.src" --no-out-link)"
+
+WORK_DIR="$(mktemp -d)"
+trap 'rm -rf "$WORK_DIR"' EXIT
+
+# NOTE: dwyane/elm2nix should be used ideally BUT we can't use it
+# Due to https://github.com/dwayne/elm2nix/issues/3
+
+# for elm to be able to write into local folders
+cp -r "$SRC_DIR"/* "$WORK_DIR"/
+chmod -R +w "$WORK_DIR"
+
+cd "$WORK_DIR"
+
+# clean elm home
+export ELM_HOME="$WORK_DIR/.elm"
+
+# for every elm.json in the repo force elm to resolve it
+while read -r elm_file; do
+  (
+    dir=$(dirname "$elm_file")
+    echo "Resolving Elm dependencies in $dir"
+    cd "$dir"
+    # 'elm make' on a non-existent file will fail, but not before it
+    # solves and downloads all dependencies in the elm.json!
+    elm make src/Fake.elm --output=/dev/null >/dev/null 2>&1 || true
+  ) &
+done < <(find . -name "elm.json" -type f)
+
+wait
+
+ELM_PACKAGES="$ELM_HOME/$ELM_VERSION/packages"
+
+if [ ! -d "$ELM_PACKAGES" ]; then
+  echo "Error: Elm cache was not generated at $ELM_PACKAGES" >&2
+  exit 1
+fi
+
+# crawl the cache and collect dependencies
+deps=()
+for author_dir in "$ELM_PACKAGES"/*; do
+  [ -d "$author_dir" ] || continue
+  author=$(basename "$author_dir")
+  for package_dir in "$author_dir"/*; do
+    [ -d "$package_dir" ] || continue
+    package=$(basename "$package_dir")
+    for version_dir in "$package_dir"/*; do
+      [ -d "$version_dir" ] || continue
+      version=$(basename "$version_dir")
+      deps+=("$author $package $version")
+    done
+  done
+done
+
+# add this dependency separately, the program adds it at runtime before running the tests
+# the version is obtained from src/deps.rs
+RUNNER_VERSION=$(grep -A 1 'Pkg::new("mpizenberg", "elm-test-runner")' "$WORK_DIR/src/deps.rs" | grep "Range::exact" | sed 's/.*(\([0-9]*\), \([0-9]*\), \([0-9]*\)).*/\1.\2.\3/')
+deps+=("mpizenberg elm-test-runner $RUNNER_VERSION")
+
+echo "Prefetching ${#deps[@]} Elm dependencies"
+
+# fetch hashes in parallel and combine into JSON
+fetch_dep() {
+  local author=$1
+  local package=$2
+  local version=$3
+  local url="https://github.com/${author}/${package}/archive/${version}.tar.gz"
+  local sha256
+
+  if sha256=$(nix-prefetch-url --unpack "$url" 2>/dev/null); then
+    # Generate an isolated JSON object for this dependency
+    jq -n --arg author "$author" --arg package "$package" --arg version "$version" --arg sha256 "$sha256" \
+      '{author: $author, package: $package, version: $version, sha256: $sha256}'
+  else
+    echo "Failed to fetch $url" >&2
+    exit 1
+  fi
+}
+export -f fetch_dep
+
+# run up to 8 fetches concurrently, and merge outputs into an array
+# we create a dwayne/elm2nix compatible lock file
+printf "%s\n" "${deps[@]}" |
+  xargs -n 3 -P 8 bash -c 'fetch_dep "$1" "$2" "$3"' _ |
+  jq -s 'sort_by(.author, .package, .version)' >"$PACKAGE_DIR/elm-srcs.json"
+
+
+# create a registry.dat for just this lockfile using dwayne/elm2nix
+# this file is very important and has the exact information required for elm to work offline
+# with incomplete registry info it will fail at runtime while trying to validate it
+"$(
+  nix build \
+  --extra-experimental-features "flakes nix-command" \
+  github:dwayne/elm2nix/ea5293850cc98d7acd3f7fc45fc95d9308334e27 \
+  --print-out-paths --no-link \
+)"/bin/elm2nix \
+  registry generate \
+  -i "$PACKAGE_DIR/elm-srcs.json" \
+  -o "$PACKAGE_DIR/registry.dat"
+
+echo "Files elm-srcs.json and registry.dat updated successfully"