Allow configuring debugExpressionTimeoutMs (#613)

* Allow configuring debugExpressionTimeoutMs

Rather than a hard-coded timeout of 1_000 ms for watch expressions, add
`debugExpressionTimeoutMs` to the launch.json configuration options. In
the next version of vscode-elixir-ls `debugExpressionTimeoutMs` will be
supported in the launch.json autocomplete, but if you are running a
version of ElixirLS that supports it before then you can add the key
manually.

Example mix test launch.json entry that uses this to set a timeout of 30
seconds:
```
{
    "type": "mix_task",
    "name": "mix test",
    "request": "launch",
    "debugExpressionTimeoutMs": 30000,
    "task": "test",
    "taskArgs": [
        "--trace"
    ],
    "startApps": true,
    "projectDir": "${workspaceRoot}",
    "requireFiles": [
        "test/**/test_helper.exs",
        "test/**/*_test.exs"
    ]
}
```

Fixes #525

* Fix test

apps/elixir_ls_debugger/lib/debugger/server.ex

@@ -400,7 +400,7 @@ defmodule ElixirLS.Debugger.Server do
          request(_cmd, "evaluate", %{"expression" => expr} = _args),
          state = %__MODULE__{}
        ) do
-    timeout = 1_000
+    timeout = Map.get(state.config, "debugExpressionTimeoutMs", 10_000)
     bindings = all_variables(state.paused_processes)
 
     result = evaluate_code_expression(expr, bindings, timeout)

apps/elixir_ls_debugger/test/debugger_test.exs

@@ -509,7 +509,7 @@ defmodule ElixirLS.Debugger.ServerTest do
   end
 
   describe "Watch section" do
-    defp gen_packet(expr) do
+    defp gen_watch_expression_packet(expr) do
       %{
         "arguments" => %{
           "context" => "watch",
@@ -527,7 +527,7 @@ defmodule ElixirLS.Debugger.ServerTest do
 
       Server.receive_packet(
         server,
-        gen_packet("1 + 2 + 3 + 4")
+        gen_watch_expression_packet("1 + 2 + 3 + 4")
       )
 
       assert_receive(%{"body" => %{"result" => "10"}}, 1000)
@@ -541,7 +541,7 @@ defmodule ElixirLS.Debugger.ServerTest do
 
       Server.receive_packet(
         server,
-        gen_packet("1 = 2")
+        gen_watch_expression_packet("1 = 2")
       )
 
       assert_receive(%{"body" => %{"result" => result}}, 1000)
@@ -556,7 +556,7 @@ defmodule ElixirLS.Debugger.ServerTest do
 
       Server.receive_packet(
         server,
-        gen_packet("Process.exit(self(), :normal)")
+        gen_watch_expression_packet("Process.exit(self(), :normal)")
       )
 
       assert_receive(%{"body" => %{"result" => result}}, 1000)
@@ -571,7 +571,7 @@ defmodule ElixirLS.Debugger.ServerTest do
 
       Server.receive_packet(
         server,
-        gen_packet("throw(:goodmorning_bug)")
+        gen_watch_expression_packet("throw(:goodmorning_bug)")
       )
 
       assert_receive(%{"body" => %{"result" => result}}, 1000)
@@ -583,10 +583,24 @@ defmodule ElixirLS.Debugger.ServerTest do
 
     test "Evaluate expression which has long execution", %{server: server} do
       Server.receive_packet(server, initialize_req(1, %{}))
+      assert_receive(response(_, 1, "initialize", %{"supportsConfigurationDoneRequest" => true}))
+
+      Server.receive_packet(
+        server,
+        launch_req(2, %{
+          "request" => "launch",
+          "type" => "mix_task",
+          "task" => "test",
+          "projectDir" => File.cwd!(),
+          "debugExpressionTimeoutMs" => 500
+        })
+      )
+
+      assert_receive(response(_, 2, "launch", %{}), 5000)
 
       Server.receive_packet(
         server,
-        gen_packet(":timer.sleep(10_000)")
+        gen_watch_expression_packet(":timer.sleep(10_000)")
       )
 
       assert_receive(%{"body" => %{"result" => result}}, 1100)