Reload Mix.State from env after loading client settings

Fixes elixir-lsp/vscode-elixir-ls#324

Author: lukaszsamson

CHANGELOG.md

@@ -1,5 +1,9 @@
 ### Unreleased
 
+#### Fixes
+
+- Fixed regression in debugger not respecting `MIX_ENV` and `MIX_TARGET`
+
 ### v0.14.4: 20 April 2023
 
 #### Fixes

apps/elixir_ls_debugger/lib/debugger/server.ex

@@ -27,6 +27,7 @@ defmodule ElixirLS.Debugger.Server do
   }
 
   alias ElixirLS.Debugger.Stacktrace.Frame
+  alias ElixirLS.Utils.Launch
   use GenServer
   use Protocol
 
@@ -937,9 +938,10 @@ defmodule ElixirLS.Debugger.Server do
     # the startup sequence here is taken from
     # https://github.com/elixir-lang/elixir/blob/v1.14.4/lib/mix/lib/mix/cli.ex#L158
     # we assume that mix is already started and has archives and tasks loaded
-    ElixirLS.Utils.Launch.load_mix_exs()
-    {task, task_args} = ElixirLS.Utils.Launch.get_task(List.wrap(task) ++ task_args)
-    ElixirLS.Utils.Launch.maybe_change_env_and_target(task)
+    Launch.reload_mix_env_and_target()
+    Launch.load_mix_exs()
+    {task, task_args} = Launch.get_task(List.wrap(task) ++ task_args)
+    Launch.maybe_change_env_and_target(task)
 
     Output.debugger_console("Running with MIX_ENV: #{Mix.env()} MIX_TARGET: #{Mix.target()}\n")
 

apps/elixir_ls_utils/lib/launch.ex

@@ -163,4 +163,20 @@ defmodule ElixirLS.Utils.Launch do
     The --help and --version options can be given instead of a task for usage and versioning information.
     """)
   end
+
+  defp from_env(varname, default) do
+    case System.get_env(varname) do
+      nil -> default
+      "" -> default
+      value -> String.to_atom(value)
+    end
+  end
+
+  # this code is executed on Mix.State.init
+  # since we start mix earlier with language server/debugger
+  # we need to reinitialize Mix.State when env is loaded form client settings
+  def reload_mix_env_and_target() do
+    Mix.env(from_env("MIX_ENV", :dev))
+    Mix.target(from_env("MIX_TARGET", :host))
+  end
 end

apps/language_server/lib/language_server/server.ex

@@ -1146,7 +1146,7 @@ defmodule ElixirLS.LanguageServer.Server do
       state
       |> maybe_set_env_vars(env_vars)
       |> set_mix_env(mix_env)
-      |> maybe_set_mix_target(mix_target)
+      |> set_mix_target(mix_target)
       |> set_project_dir(project_dir)
       |> set_dialyzer_enabled(enable_dialyzer)
       |> add_watched_extensions(additional_watched_extensions)
@@ -1217,10 +1217,17 @@ defmodule ElixirLS.LanguageServer.Server do
     state
   end
 
+  defp set_mix_env(state = %__MODULE__{}, env) when env in [nil, ""] do
+    # mix defaults to :dev env but we choose :test as this results in better
+    # support for test files
+    set_mix_env(state, "test")
+  end
+
   defp set_mix_env(state = %__MODULE__{}, env) do
     prev_env = state.settings["mixEnv"]
 
     if is_nil(prev_env) or env == prev_env do
+      System.put_env("MIX_ENV", env)
       Mix.env(String.to_atom(env))
     else
       JsonRpc.show_message(:warning, "Mix env change detected. ElixirLS will restart.")
@@ -1232,18 +1239,16 @@ defmodule ElixirLS.LanguageServer.Server do
     state
   end
 
-  defp maybe_set_mix_target(state = %__MODULE__{}, nil), do: state
-
-  defp maybe_set_mix_target(state = %__MODULE__{}, ""), do: state
-
-  defp maybe_set_mix_target(state = %__MODULE__{}, target) do
-    set_mix_target(state, target)
+  defp set_mix_target(state = %__MODULE__{}, target) when target in [nil, ""] do
+    # mix defaults to :host target
+    set_mix_target(state, "host")
   end
 
   defp set_mix_target(state = %__MODULE__{}, target) do
     prev_target = state.settings["mixTarget"]
 
     if is_nil(prev_target) or target == prev_target do
+      System.put_env("MIX_TARGET", target)
       Mix.target(String.to_atom(target))
     else
       JsonRpc.show_message(:warning, "Mix target change detected. ElixirLS will restart")