Support Elixir 1.17

The latest Elixir changed how IEx should be started. The current
way we're using is `IEx.start` which is still around in 1.17 but
only arity 0. So if you include any shell_opts, the IEx session would immediately crash. If you don't use shell_opts, then things will work as normal.

This makes the needed adjustments to work with Elixir 1.17 and
support shell_opts, including a change to account for .iex.exs
files in the arguments

.circleci/config.yml

@@ -1,7 +1,7 @@
 version: 2.1
 
 latest: &latest
-  pattern: "^1.15.2-erlang-26.*$"
+  pattern: "^1.17.*-erlang-27.*$"
 
 jobs:
   build-test:
@@ -52,6 +52,8 @@ workflows:
           matrix:
             parameters:
               tag: [
+                1.17.2-erlang-27.0.1-alpine-3.20.1,
+                1.16.3-erlang-26.2.5.2-alpine-3.20.1,
                 1.15.2-erlang-26.0.2-alpine-3.18.2,
                 1.14.5-erlang-25.3.2-alpine-3.18.0,
                 1.13.4-erlang-25.3.2-alpine-3.18.0,

lib/extty.ex

@@ -116,8 +116,31 @@ defmodule ExTTY do
     {:shell, :start, opts}
   end
 
-  defp shell_spawner(%{type: :elixir, shell_opts: opts}) do
-    {Elixir.IEx, :start, opts}
+  if Version.match?(System.version(), ">= 1.17.0") do
+    defp shell_spawner(%{type: :elixir, shell_opts: opts}) do
+      # :iex.start/0 is now the recommended way to start IEx, but
+      # we want to support the options so we're using the mostly
+      # private API :iex.start/2 which takes the options as a
+      # keyword list and an MFA (which is same one used in :iex.start/0).
+      #
+      # Previously, the shell opts needed to be a double list since it
+      # was passed directly to an MFA, so we need to flatten it here.
+      # Then we also normalize the dot_iex_path arg to match the Elixir 1.17
+      # change to normalize the arg across the code
+      shell_opts =
+        opts
+        |> List.flatten()
+        |> Enum.map(fn
+          {:dot_iex_path, path} -> {:dot_iex, path}
+          kv -> kv
+        end)
+
+      {:iex, :start, [shell_opts, {:elixir_utils, :noop, []}]}
+    end
+  else
+    defp shell_spawner(%{type: :elixir, shell_opts: opts}) do
+      {Elixir.IEx, :start, opts}
+    end
   end
 
   defp shell_spawner(state) do

test/extty_test.exs

@@ -2,7 +2,7 @@ defmodule ExTTYTest do
   use ExUnit.Case
   doctest ExTTY
 
-  test "that Elixir starts" do
+  test "that Elixir starts by default" do
     start_supervised!({ExTTY, [handler: self()]})
 
     assert_receive {:tty_data, message}
@@ -15,6 +15,26 @@ defmodule ExTTYTest do
     refute_receive _
   end
 
+  @tag :tmp_dir
+  test "that Elixir starts with .iex.exs option", %{tmp_dir: tmp_dir} do
+    dot_iex = "alias ExTTY, as: TTY"
+    dot_iex_path = Path.join(tmp_dir, "iex.exs")
+    File.write!(dot_iex_path, dot_iex)
+
+    start_supervised!(
+      {ExTTY, [handler: self(), type: :elixir, shell_opts: [[dot_iex_path: dot_iex_path]]]}
+    )
+
+    assert_receive {:tty_data, message}
+    assert message =~ "Interactive Elixir"
+
+    # Expect a prompt
+    assert_receive {:tty_data, "iex(1)> "}
+
+    # # Nothing else
+    refute_receive _
+  end
+
   test "that Erlang starts" do
     start_supervised!({ExTTY, [type: :erlang, handler: self()]})