From d3ea64cc15518c8a92ee9e3bf8b437eb29074dd4 Mon Sep 17 00:00:00 2001
From: Robert Prehn <3952444+prehnRA@users.noreply.github.com>
Date: Mon, 30 Mar 2026 15:43:34 -0500
Subject: [PATCH] Add infrastructure for JS testing

---
 config/test.exs           |   3 +
 js/index.mjs              |  14 +++
 lib/beam_js.ex            | 134 ++------------------------
 lib/beam_js/boxed.ex      |   3 +
 lib/beam_js/encoder.ex    | 191 ++++++++++++++++++++++++++++++++++++++
 lib/beam_js/function.ex   |  21 +++++
 lib/beam_js/js_runtime.ex |  53 +++++++++++
 lib/beam_js/module.ex     |  32 +++++++
 lib/beam_js/utils.ex      |   4 +
 mix.exs                   |   4 +
 mix.lock                  |   3 +
 test/beam_js_test.exs     |  17 +++-
 test/support/example.ex   |   5 +
 test/support/js_case.ex   |  14 +++
 test/test_helper.exs      |   1 +
 15 files changed, 368 insertions(+), 131 deletions(-)
 create mode 100644 config/test.exs
 create mode 100644 js/index.mjs
 create mode 100644 lib/beam_js/boxed.ex
 create mode 100644 lib/beam_js/encoder.ex
 create mode 100644 lib/beam_js/function.ex
 create mode 100644 lib/beam_js/js_runtime.ex
 create mode 100644 lib/beam_js/module.ex
 create mode 100644 lib/beam_js/utils.ex
 create mode 100644 test/support/example.ex
 create mode 100644 test/support/js_case.ex

diff --git a/config/test.exs b/config/test.exs
new file mode 100644
index 0000000..a59b9c0
--- /dev/null
+++ b/config/test.exs
@@ -0,0 +1,3 @@
+import Config
+
+config :nodejs, debug_mode: true
diff --git a/js/index.mjs b/js/index.mjs
new file mode 100644
index 0000000..3a6fae0
--- /dev/null
+++ b/js/index.mjs
@@ -0,0 +1,14 @@
+class Boxed {
+  constructor(type, value) {
+    this.type = type;
+    this.value = value;
+  }
+}
+
+export const boxed = (type, value) => {
+  return new Boxed(type, value);
+};
+
+export default {
+  boxed,
+};
diff --git a/lib/beam_js.ex b/lib/beam_js.ex
index bc3d615..08eaf8f 100644
--- a/lib/beam_js.ex
+++ b/lib/beam_js.ex
@@ -2,132 +2,10 @@ defmodule BeamJs do
   @moduledoc """
   Documentation for `BeamJs`.
   """
-  require Logger
-
-  def module_code(module) do
-    module
-    |> BeamFile.byte_code()
-    |> ok(fn {_, _, _, _, _, sections} ->
-      {:ok, Enum.filter(sections, fn
-        {:function, _fun_name, _arity, _, _code} ->
-          true
-        _other ->
-          false
-      end)}
-    end)
-    |> ok(fn functions ->
-      Enum.map(functions, fn {:function, name, arity, _, code} ->
-        {"#{name}/#{arity}", transform_function_code(code)}
-      end)
-      |> Map.new()
-    end)
-  end
-
-  def transform_function_code(ops) do
-    Enum.reduce(ops, [], fn
-      {:label, number}, [{line_no, head_ops} | tail] ->
-        [{number, []} | [{line_no, Enum.reverse(head_ops)} | tail]]
-
-      {:label, number}, acc ->
-        [{number, []} | acc]
-
-      {:line, _line_number}, [] ->
-        []
-
-      other_op, [{number, head} | tail] ->
-        [{number, [other_op|head]} | tail]
-    end)
-    |> Enum.reverse()
-  end
-
-  def encode_fun(label_sections) do
-    "{\n" <> Enum.map_join(label_sections, ",\n", fn {label, ops} ->
-      body = Enum.map_join(ops, "", &encode_op/1)
-      "  #{label}: (p) => {\n#{body}}"
-    end) <> "}"
-  end
-
-  def encode_op(tuple) when is_tuple(tuple) do
-    op_name = elem(tuple, 0)
-    args =
-      try do
-        encode_args(tuple)
-      rescue
-        e ->
-          Logger.error("Error encoding op: #{inspect(tuple)}")
-          reraise e, __STACKTRACE__
-      end
-
-    "    BeamJs.Ops.#{op_name}(p, " <> Enum.join(args, ", ") <> ");\n"
-  end
-
-  def encode_op(atom) when is_atom(atom), do: "    BeamJs.Ops.#{atom}(p);\n"
-
-  def encode_args({:allocate, frame_size, live}), do: [number(frame_size), number(live)]
-  def encode_args({:line, number}), do: [number(number)]
-  def encode_args({:func_info, {:atom, m}, {:atom, f}, arity}), do: [quoted_string(m), quoted_string(f), number(arity)]
-  def encode_args({:select_val, source, {:f, fail_label}, comparison}), do: [encode_source(source), number(fail_label), encode_value(comparison)]
-  def encode_args({:move, source, {register_bank, number}}) when register_bank in [:x, :y], do: [encode_source(source), quoted_string(register_bank), number(number)]
-  def encode_args({:call, _live, {_m, f, a}}), do: [quoted_string(f), number(a)]
-  def encode_args({:call_ext_only, _live, {:extfunc, m, f, a}}), do: [quoted_string(m), quoted_string(f), number(a)]
-  def encode_args({:call_only, _live, {_m, f, a}}), do: [quoted_string(f), number(a)]
-  def encode_args({:deallocate, live}), do: [number(live)]
-  def encode_args({:gc_bif, bif, {:f, fail_to}, _unknown, args, {register_bank, number}}) when register_bank in [:x, :y] do
-    [
-      quoted_string(bif),
-      number(fail_to),
-      "[" <> (args |> Enum.map(&encode_source/1) |> Enum.join(", ")) <> "]",
-      register_bank,
-      number
-    ]
-  end
-
-  def encode_source({:tr, source, _}), do: encode_source(source)
-  def encode_source({:x, number}), do: "p.registers.x[#{number}]"
-  def encode_source({:y, number}), do: "p.registers.y[#{number}]"
-  def encode_source({:integer, number}), do: number(number)
-  def encode_source(value), do: encode_value(value)
-
-
-  def encode_value({:literal, value}), do: encode_value(value)
-
-  def encode_value({type, value}) when type in [:atom, :x, :y, :list] do
-    ~s|BeamJs.boxed("#{type}", #{encode_value(value)})|
-  end
-
-  def encode_value(tuple) when is_tuple(tuple) do
-    ~s|BeamJs.boxed("tuple", #{encode_value(Tuple.to_list(tuple))})|
-  end
-
-  def encode_value(value) when is_binary(value) do
-    if String.valid?(value) do
-      quoted_string(value)
-    else
-      # Likely a raw bytes array
-      base64 = value |> Base.encode64() |> quoted_string()
-      ~s|atob(#{base64})|
-    end
-  end
-
-  def encode_value(value) when is_list(value) do
-    ~s|[#{Enum.map_join(value, ", ", &encode_value/1)}]|
-  end
-
-  def encode_value(value) when is_atom(value) do
-    quoted_string(value)
-  end
-
-  def encode_value(value) when is_number(value) do
-    "#{value}"
-  end
-
-  defp quoted_string(v), do: ~s|"#{v}"|
-  defp number(n), do: "#{n}"
-
-  def fact(0), do: 1
-  def fact(1), do: 1
-  def fact(n), do: fact(n - 1) + fact(n - 2)
-
-  defp ok({:ok, value}, fun), do: fun.(value)
-  defp ok(other, _fun), do: other
+end
+
+defimpl JSON.Encoder, for: BeamJs.Boxed do
+  def encode(value, encoder) do
+    ["BeamJs.boxed(", encoder.(value.type, encoder), ", ", encoder.(value.value, encoder),")"]
+  end
 end
diff --git a/lib/beam_js/boxed.ex b/lib/beam_js/boxed.ex
new file mode 100644
index 0000000..a2d2660
--- /dev/null
+++ b/lib/beam_js/boxed.ex
@@ -0,0 +1,3 @@
+  defmodule BeamJs.Boxed do
+    defstruct [:type, :value]
+  end
diff --git a/lib/beam_js/encoder.ex b/lib/beam_js/encoder.ex
new file mode 100644
index 0000000..99cba9b
--- /dev/null
+++ b/lib/beam_js/encoder.ex
@@ -0,0 +1,191 @@
+defmodule BeamJs.Encoder do
+  require Logger
+  
+  alias BeamJs.Boxed
+
+  def encode_module(mod_ast) do
+    "import BeamJs from '../js/index.mjs';\n" <>
+    (
+      mod_ast
+      |> Enum.map_join("\n", fn {fn_name, ops} ->
+        encode_fun_to_js_export(ops, fn_name)
+      end)
+    )
+  end
+
+  def encode_fun_to_js_value(label_sections) do
+    Enum.map(label_sections, fn {label, ops} ->
+      body = Enum.map(ops, &encode_op/1)
+      [label, body]
+    end)
+    |> JSON.encode!()
+  end
+
+  def encode_fun_to_js_export(label_sections, function_name) do
+    label_sections
+    |> encode_fun_to_js_value()
+    |> then(&"export const #{function_name} = #{&1};")
+  end
+
+  def encode_op(tuple) when is_tuple(tuple) do
+    op_name = elem(tuple, 0)
+    args =
+      try do
+        encode_op_args(tuple)
+      rescue
+        e ->
+          Logger.error("Error encoding op: #{inspect(tuple)}")
+          reraise e, __STACKTRACE__
+      end
+
+    [op_name | args]
+  end
+
+  def encode_op(atom) when is_atom(atom), do: [atom]
+
+  def encode_op_args(op)
+  def encode_op_args({:allocate, frame_size, live}), do: [frame_size, live]
+  def encode_op_args({:allocate_heap, n, {:alloc, list}, n2}) do
+    [
+      n,
+      Enum.map(list, &encode_value/1),
+      n2
+    ]
+  end
+  def encode_op_args({:bs_create_bin, {:f, fail_to}, alloc, live, unit, {dest_bank, dest_number}, {:list, segments}}) do
+    [
+      fail_to,
+      alloc,
+      live,
+      unit,
+      dest_bank,
+      dest_number,
+      Enum.map(segments, &encode_value/1)
+    ]
+  end
+  def encode_op_args({:line, number}), do: [number]
+  def encode_op_args({:func_info, {:atom, m}, {:atom, f}, arity}), do: [Atom.to_string(m), Atom.to_string(f), arity]
+  def encode_op_args({:make_fun3, {m, f, a}, x, y, {dest_bank, dest_number}, {:list, list}}) do
+    [
+      m,
+      f,
+      a,
+      x,
+      y,
+      dest_bank,
+      dest_number,
+      Enum.map(list, &encode_value/1)
+    ]
+  end
+  def encode_op_args({:select_val, source, {:f, fail_label}, {:list, f_list}}), do: [encode_source(source), fail_label, encode_f_list(f_list)]
+  def encode_op_args({:move, source, dest}), do: [encode_source(source), encode_source(dest)]
+  def encode_op_args({:call, _live, {_m, f, a}}), do: [f, a]
+  def encode_op_args({:call_ext, _live, {:extfunc, m, f, a}}), do: [m, f, a]
+  def encode_op_args({:call_ext_only, _live, {:extfunc, m, f, a}}), do: [m, f, a]
+  def encode_op_args({:call_only, _live, {_m, f, a}}), do: [f, a]
+  def encode_op_args({:deallocate, live}), do: [live]
+  def encode_op_args({:gc_bif, bif, {:f, fail_to}, _unknown, args, {register_bank, number}}) when register_bank in [:x, :y] do
+    [
+      bif,
+      fail_to,
+      Enum.map(args, &encode_source/1),
+      register_bank,
+      number
+    ]
+  end
+  def encode_op_args({:get_tuple_element, {source_bank, source_number}, index, {dest_bank, dest_number}}) when source_bank in [:x, :y] and dest_bank in [:x, :y] do
+    [
+      source_bank,
+      source_number,
+      index,
+      dest_bank,
+      dest_number
+    ]
+  end
+  def encode_op_args({:init_yregs, {:list, sources}}), do: [Enum.map(sources, &encode_source/1)]
+  def encode_op_args({:jump, {:f, to}}), do: [to]
+  def encode_op_args({:put_list, {bank_a, number_a}, {bank_b, number_b}, {bank_c, number_c}}), do: [bank_a, number_a, bank_b, number_b, bank_c, number_c]
+  def encode_op_args({:put_list, {bank_a, number_a}, nil, {bank_c, number_c}}), do: [bank_a, number_a, nil, nil, bank_c, number_c]
+  def encode_op_args({:bif, bif, {:f, fail_to}, args, {register_bank, number}}) when register_bank in [:x, :y] do
+    [
+      bif,
+      fail_to,
+      Enum.map(args, &encode_source/1),
+      register_bank,
+      number
+    ]
+  end
+  def encode_op_args({:select_tuple_arity, {:tr, {source_bank, source_number}, {:t_tuple, 0, false, %{}}}, {:f, fail_to},
+         {:list, f_list}}) do
+    [
+      source_bank,
+      source_number,
+      fail_to,
+      encode_f_list(f_list)
+    ]
+  end
+  def encode_op_args({:swap, {a_bank, a_n}, {b_bank, b_n}}), do: [a_bank, a_n, b_bank, b_n]
+  def encode_op_args({:test, test_name, {:f, fail_to}, args}) do
+     [
+       test_name,
+       fail_to,
+       Enum.map(args, &encode_source/1)
+     ]
+  end
+  def encode_op_args({:test_heap, {:alloc, list}, b}), do: [Enum.map(list, &encode_value/1), b]
+  def encode_op_args({:test_heap, a, b}), do: [a, b]
+  def encode_op_args({:trim, n, remaining}), do: [n, remaining]
+  def encode_op_args({:try, {register_bank, number}, {:f, fail_to}}) when register_bank in [:x, :y], do: [register_bank, number, fail_to]
+  def encode_op_args({:try_case, {register_bank, number}}) when register_bank in [:x, :y], do: [register_bank, number]
+  def encode_op_args({:try_end, {register_bank, number}}) when register_bank in [:x, :y], do: [register_bank, number]
+
+  def encode_f_list(comparison) do
+    comparison
+    |> Enum.chunk_every(2)
+    |> Enum.map(fn [value, {:f, number}] ->
+      [encode_value(value), number]
+    end)
+  end
+
+  def encode_source({:tr, source, _}), do: encode_source(source)
+  def encode_source({:x, number}), do: [:x, number]
+  def encode_source({:y, number}), do: [:y, number]
+  def encode_source(value), do: encode_value(value)
+
+
+  def encode_value({:literal, value}), do: encode_value(value)
+
+  def encode_value({type, value}) when type in [:atom, :list, :integer] do
+    %Boxed{type: type, value: value}
+  end
+
+  def encode_value(tuple) when is_tuple(tuple) do
+    %Boxed{type: "tuple", value: encode_value(Tuple.to_list(tuple))}
+  end
+
+  def encode_value(value) when is_binary(value) do
+    if String.valid?(value) do
+      value
+    else
+      # Likely a raw bytes array
+      base64 = value |> Base.encode64() |> quoted_string()
+      ~s|atob(#{base64})|
+    end
+  end
+
+  def encode_value(value) when is_list(value) do
+    Enum.map(value, &encode_value/1)
+  end
+
+  def encode_value(value) when is_atom(value) do
+    %Boxed{type: :atom, value: value}
+  end
+
+  def encode_value(value) when is_integer(value) do
+    %Boxed{type: :integer, value: value}
+  end
+
+  def encode_value(map) when is_map(map), do: %Boxed{type: :map, value: map |> Enum.map(fn {key, value} -> {encode_value(key), encode_value(value)} end) |> Map.new()}
+
+  defp quoted_string(v), do: ~s|"#{v}"|
+end
diff --git a/lib/beam_js/function.ex b/lib/beam_js/function.ex
new file mode 100644
index 0000000..fe24a19
--- /dev/null
+++ b/lib/beam_js/function.ex
@@ -0,0 +1,21 @@
+defmodule BeamJs.Function do
+  def to_ast(ops) do
+    Enum.reduce(ops, [], fn
+      {:label, number}, [{line_no, head_ops} | tail] ->
+        [{number, []} | [{line_no, Enum.reverse(head_ops)} | tail]]
+
+      {:label, number}, acc ->
+        [{number, []} | acc]
+
+      {:line, _line_number}, [] ->
+        []
+
+      other_op, [{number, head} | tail] ->
+        [{number, [other_op|head]} | tail]
+    end)
+    |> then(fn [{label, head_ops}|tail] ->
+      [{label, Enum.reverse(head_ops)}|tail]
+    end)
+    |> Enum.reverse()
+  end
+end
diff --git a/lib/beam_js/js_runtime.ex b/lib/beam_js/js_runtime.ex
new file mode 100644
index 0000000..405ff96
--- /dev/null
+++ b/lib/beam_js/js_runtime.ex
@@ -0,0 +1,53 @@
+defmodule BeamJs.JsRuntime do
+  use GenServer
+
+  def start_link() do
+    GenServer.start_link(__MODULE__, [])
+  end
+
+  def run(pid, code) do
+    GenServer.call(pid, {:run, code})
+  end
+
+  @impl GenServer
+  def init(_opts) do
+    path = System.find_executable("node")
+    port = Port.open({:spawn_executable, path}, [:binary, args: ["-i"]])
+    wait_for_prompt()
+
+    {:ok, %{port: port}}
+  end
+
+  @impl GenServer
+  def handle_call({:run, code}, _from, %{port: port} = state) do
+    send(port, {self(), {:command, code <> "\r\n"}})
+    result =
+      receive do
+        {_port, {:data, msg}} -> msg
+      end
+
+    result =
+      result
+      |> String.trim_trailing("\n> ")
+      |> String.trim("'")
+    case JSON.decode(result) do
+      {:ok, result} ->
+        {:reply, {:ok, result}, state}
+      {:error, _decode_error} ->
+        {:reply, {:error, result}, state}
+    end
+  end
+
+  @impl GenServer
+  def terminate(_reason, %{port: port}) do
+    Port.close(port)
+  end
+
+  defp wait_for_prompt do
+    receive do
+      {_port, {:data, "> "}} -> :ok
+      {_port, {:data, _other}} ->
+        wait_for_prompt()
+    end
+  end
+end
diff --git a/lib/beam_js/module.ex b/lib/beam_js/module.ex
new file mode 100644
index 0000000..04aa69d
--- /dev/null
+++ b/lib/beam_js/module.ex
@@ -0,0 +1,32 @@
+defmodule BeamJs.Module do
+  import BeamJs.Utils
+
+  alias BeamJs.Function
+  
+  def to_ast(module, opts \\ []) do
+    function_map =
+      module
+      |> BeamFile.byte_code()
+      |> ok(fn {_, _, _, _, _, sections} ->
+        {:ok, Enum.filter(sections, fn
+          {:function, _fun_name, _arity, _, _code} ->
+            true
+          _other ->
+            false
+        end)}
+      end)
+      |> ok(fn functions ->
+        Enum.map(functions, fn {:function, name, arity, _, code} ->
+          {"#{name}$#{arity}", Function.to_ast(code)}
+        end)
+        |> Map.new()
+      end)
+
+    case Keyword.get(opts, :only) do
+      nil ->
+        function_map
+      only ->
+        Map.take(function_map, only)
+    end
+  end
+end
diff --git a/lib/beam_js/utils.ex b/lib/beam_js/utils.ex
new file mode 100644
index 0000000..adfe81b
--- /dev/null
+++ b/lib/beam_js/utils.ex
@@ -0,0 +1,4 @@
+defmodule BeamJs.Utils do
+  def ok({:ok, value}, fun), do: fun.(value)
+  def ok(other, _fun), do: other
+end
diff --git a/mix.exs b/mix.exs
index d6ec3df..200e7ae 100644
--- a/mix.exs
+++ b/mix.exs
@@ -6,11 +6,15 @@ defmodule BeamJs.MixProject do
       app: :beam_js,
       version: "0.1.0",
       elixir: "~> 1.19",
+      elixirc_paths: elixirc_paths(Mix.env()),
       start_permanent: Mix.env() == :prod,
       deps: deps()
     ]
   end
 
+  def elixirc_paths(:test), do: ["lib", "test/support"]
+  def elixirc_paths(_), do: ["lib"]
+
   # Run "mix help compile.app" to learn about applications.
   def application do
     [
diff --git a/mix.lock b/mix.lock
index ddb8226..1cba670 100644
--- a/mix.lock
+++ b/mix.lock
@@ -1,3 +1,6 @@
 %{
   "beam_file": {:hex, :beam_file, "0.6.4", "73660f76330e6b29be2b8ae3779b30cb67a7803cde88a21e3e74371130eed4d4", [:mix], [], "hexpm", "3f295dba08a68360903e86be4f183d7fb70f762ee37ee176438dde23ea494431"},
+  "jason": {:hex, :jason, "1.4.4", "b9226785a9aa77b6857ca22832cffa5d5011a667207eb2a0ad56adb5db443b8a", [:mix], [{:decimal, "~> 1.0 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: true]}], "hexpm", "c5eb0cab91f094599f94d55bc63409236a8ec69a21a67814529e8d5f6cc90b3b"},
+  "poolboy": {:hex, :poolboy, "1.5.2", "392b007a1693a64540cead79830443abf5762f5d30cf50bc95cb2c1aaafa006b", [:rebar3], [], "hexpm", "dad79704ce5440f3d5a3681c8590b9dc25d1a561e8f5a9c995281012860901e3"},
+  "ssl_verify_fun": {:hex, :ssl_verify_fun, "1.1.7", "354c321cf377240c7b8716899e182ce4890c5938111a1296add3ec74cf1715df", [:make, :mix, :rebar3], [], "hexpm", "fe4c190e8f37401d30167c8c405eda19469f34577987c76dde613e838bbc67f8"},
 }
diff --git a/test/beam_js_test.exs b/test/beam_js_test.exs
index e326d3b..ca4ecf6 100644
--- a/test/beam_js_test.exs
+++ b/test/beam_js_test.exs
@@ -1,8 +1,19 @@
 defmodule BeamJsTest do
-  use ExUnit.Case
+  use BeamJs.JsCase
   doctest BeamJs
 
-  test "greets the world" do
-    assert BeamJs.hello() == :world
+  test "can run JS code", %{js: js} do
+    assert run(js, "1") == {:ok, 1}
+  end
+
+  test "can encode and import", %{js: js} do
+    js_src =
+      Example
+      |> BeamJs.Module.to_ast(only: ["fact$1"])
+      |> BeamJs.Encoder.encode_module()
+
+    File.write!("tmp/example.mjs", js_src)
+
+    assert {:ok, [[_label, [["func_info", "Elixir.Example", "fact", 1]]]| _rest]} = run(js, ~s|const Example = await import('./tmp/example.mjs');JSON.stringify(Example.fact$1)|)
   end
 end
diff --git a/test/support/example.ex b/test/support/example.ex
new file mode 100644
index 0000000..2bbc2b4
--- /dev/null
+++ b/test/support/example.ex
@@ -0,0 +1,5 @@
+defmodule Example do
+  def fact(0), do: 1
+  def fact(1), do: 1
+  def fact(n), do: fact(n - 1) + fact(n - 2)
+end
diff --git a/test/support/js_case.ex b/test/support/js_case.ex
new file mode 100644
index 0000000..a39843c
--- /dev/null
+++ b/test/support/js_case.ex
@@ -0,0 +1,14 @@
+defmodule BeamJs.JsCase do
+  use ExUnit.CaseTemplate
+
+  using do
+    quote do
+      import BeamJs.JsRuntime, only: [run: 2]
+    end
+  end
+
+  setup _tags do
+    {:ok, pid} = BeamJs.JsRuntime.start_link() 
+    %{js: pid}
+  end
+end
diff --git a/test/test_helper.exs b/test/test_helper.exs
index 869559e..0a76a58 100644
--- a/test/test_helper.exs
+++ b/test/test_helper.exs
@@ -1 +1,2 @@
 ExUnit.start()
+