Fix list rendering

dev.exs

@@ -74,8 +74,11 @@ defmodule Demo.Populator do
         posts: [
           %Demo.Posts.Post{
             title: Faker.Lorem.paragraph(1) |> String.slice(0..9),
+            categories: Ecto.Enum.values(Demo.Posts.Post, :categories) |> Enum.take(Enum.random(0..2)),
+            tags: Faker.Lorem.words(Enum.random(0..5)),
             body: Faker.Lorem.paragraphs() |> Enum.join("\n\n"),
-            disabled_user: get_user_if(:rand.uniform(2) == 1)
+            disabled_user: get_user_if(:rand.uniform(2) == 1),
+            previous_versions: [%Demo.Posts.Post.Version{body: Faker.Lorem.paragraphs() |> Enum.join("\n\n")}]
           }
         ]
       }

lib/live_admin/resource.ex

@@ -364,7 +364,10 @@ defmodule LiveAdmin.Resource do
   end
 
   defp render_field(val = %{}), do: Tag.content_tag(:pre, inspect(val, pretty: true))
-  defp render_field(val) when is_list(val), do: Enum.map_join(val, ", ", &render_field/1)
+
+  defp render_field(val) when is_list(val),
+    do: Enum.map(val, &Tag.content_tag(:pre, inspect(&1, pretty: true)))
+
   defp render_field(val) when is_binary(val), do: val
   defp render_field(val), do: inspect(val)
 end

test/live_admin/resource_test.exs

@@ -0,0 +1,24 @@
+defmodule LiveAdmin.ResourceTest do
+  use ExUnit.Case, async: true
+
+  alias LiveAdmin.Resource
+
+  setup do
+    Ecto.Adapters.SQL.Sandbox.checkout(LiveAdminTest.Repo)
+  end
+
+  describe "render/6 with a list of maps field handled by default implementation" do
+    test "returns a list with safe pre" do
+      assert Resource.render(
+               %{previous_versions: [%{}]},
+               :previous_versions,
+               LiveAdminTest.PostResource,
+               nil,
+               %{},
+               render_with: nil
+             )
+             |> List.first()
+             |> Phoenix.HTML.safe_to_string() =~ ~r/pre/
+    end
+  end
+end