From 9c9c54de6531db670bca5ec01cf0c73e4062e9f8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jonatan=20K=C5=82osko?= <jonatanklosko@gmail.com>
Date: Sat, 12 Nov 2022 19:39:59 +0100
Subject: [PATCH] Delete defined modules if evaluation fails (#1528)

---
 lib/livebook/runtime/evaluator.ex        |  7 ++++++-
 test/livebook/runtime/evaluator_test.exs | 14 ++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/lib/livebook/runtime/evaluator.ex b/lib/livebook/runtime/evaluator.ex
index f9e3bc24f..7fff0f17a 100644
--- a/lib/livebook/runtime/evaluator.ex
+++ b/lib/livebook/runtime/evaluator.ex
@@ -350,10 +350,11 @@ defmodule Livebook.Runtime.Evaluator do
     eval_result = eval(code, context.binding, context.env)
     evaluation_time_ms = time_diff_ms(start_time)
 
+    tracer_info = Evaluator.IOProxy.get_tracer_info(state.io_proxy)
+
     {new_context, result, code_error, identifiers_used, identifiers_defined} =
       case eval_result do
         {:ok, value, binding, env} ->
-          tracer_info = Evaluator.IOProxy.get_tracer_info(state.io_proxy)
           context_id = random_id()
 
           new_context = %{
@@ -370,6 +371,10 @@ defmodule Livebook.Runtime.Evaluator do
           {new_context, result, nil, identifiers_used, identifiers_defined}
 
         {:error, kind, error, stacktrace, code_error} ->
+          for {module, _} <- tracer_info.modules_defined do
+            delete_module!(module)
+          end
+
           result = {:error, kind, error, stacktrace}
           identifiers_used = :unknown
           identifiers_defined = %{}
diff --git a/test/livebook/runtime/evaluator_test.exs b/test/livebook/runtime/evaluator_test.exs
index 70ae9d121..74ada5194 100644
--- a/test/livebook/runtime/evaluator_test.exs
+++ b/test/livebook/runtime/evaluator_test.exs
@@ -334,6 +334,20 @@ defmodule Livebook.Runtime.EvaluatorTest do
       assert {:docs_v1, _, _, _, _, _, _} = Code.fetch_docs(Livebook.Runtime.EvaluatorTest.Disk)
     end
 
+    test "deletes defined modules if the evaluation fails", %{evaluator: evaluator} do
+      code = """
+      defmodule Livebook.Runtime.EvaluatorTest.Raised do
+      end
+
+      raise "failed"
+      """
+
+      Evaluator.evaluate_code(evaluator, code, :code_1, [])
+      assert_receive {:runtime_evaluation_response, :code_1, {:error, _, _, _}, metadata()}
+
+      refute Code.ensure_loaded?(Livebook.Runtime.EvaluatorTest.Raised)
+    end
+
     @tag :with_ebin_path
     test "runs doctests when a module is defined", %{evaluator: evaluator} do
       code = ~S'''