Improve debugging docs (#3298)

learning_track.md

@@ -26,6 +26,20 @@ This guide tracks useful steps to learn how to maintain and modify this system.
 * Learn how to run a single test (see readme), as this is very useful for debugging
 * :warning: All the tests should pass locally! If they don't, file an issue
 
+### Different techniques to debug stuff
+
+(More will come here later, especially with Elixir 1.15+)
+
+* `IO.puts(x)`
+* `IO.inspect(x, IEx.inspect_opts)`
+* `dbg` + `iex -S mix phx.server`
+* `find apps/transport | entr -c mix run my_script.exs`
+* `@tag :focus` and `find debug.exs apps/transport/{lib,test} | entr -c mix cmd --app transport mix test --color --only focus`
+* `mix test apps/transport/test/transport/import_data_test.exs --only focus`
+* `doctest ImportData, import: true, tags: [:focus]`
+* `elixir --sname node -S mix phx.server` and `iex --sname console --remsh node` (https://github.com/etalab/transport-site/pull/2960/files) to connect to a running node and make evaluations (useful to inspect ETS state for instance)
+* LiveBook in non-standalone mode (create a notebook then switch from standalone to connected in the settings)
+
 ### Understand the "stats" page
 
 * Check out the [/stats](https://transport.data.gouv.fr/stats) page, entry point for bizdev questions on data quality

scripts/debugging.livemd

@@ -12,9 +12,11 @@ asdf reshim elixir
 * Lancer livebook en connection au projet, avec la commande suivante:
 
 ```
-LIVEBOOK_DEFAULT_RUNTIME=mix:. livebook server --open
+livebook server
 ```
 
+* Modifier les réglages pour ne pas utiliser le mode "standalone" mais se connecter à un noeud qui tourne à la place (instructions disponibles dans LiveBook)
+
 ## Opérations liées à l'import
 
 Lors de l'ajout d'un dataset en backoffice, on donne l'url "data gouv" du dataset. Le contrôleur reçoit cette url via l'action [POST](https://github.com/etalab/transport-site/blob/605696a5638a1e80be27a674ba201c13f2820b81/apps/transport/lib/transport_web/controllers/backoffice/dataset_controller.ex#L10), puis convertit cette url en "id datagouv" comme suit: