Credo

Mix.install([
  {:jason, "~> 1.4"},
  {:kino, "~> 0.8.0", override: true},
  {:youtube, github: "brooklinjazz/youtube"},
  {:hidden_cell, github: "brooklinjazz/hidden_cell"}
])

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Setup

Ensure you type the ea keyboard shortcut to evaluate all Elixir cells before starting. Alternatively you can evaluate the Elixir cells as you read.

Credo

Credo is another static analysis tool which focuses on teaching and code consistency. It scans a project’s code for anti-patterns and provides suggestions to improve it’s quality and readability.

Your Turn

Install Credo in your math project by adding it to your dependencies in mix.exs. You can find the latest Credo version on hex.pm.

defp deps do
  [
      {:credo, "~> 1.6", only: [:dev, :test], runtime: false}
  ]
end

Ensure you install the new dependency.

$ mix deps.get

Then run the following command to see credo warnings.

$ mix credo
...
Analysis took 0.01 seconds (0.01s to load, 0.00s running 52 checks on 3 files)
3 mods/funs, found no issues.

Credo provides code suggestions that help you write idiomatic Elixir.

For example, Credo will warn you if you leave an IO.inspect/2 in your project as you probably don’t want to leave calls to IO.inspect/2 in your codebase.

Your Turn

Previously you converted a Math module into a mix project in the ExUnit with Mix section.

Add credo as a dependency to the project and leave an IO.inspect/2 call somewhere in your codebase.

Run mix credo and you should see a warning similar to the following.

$ mix credo
  Warnings - please take a look
┃
┃ [W] ↗ There should be no calls to IO.inspect/1.
┃       lib/math.ex:20:5 #(Math.test)

Please report incorrect results: https://github.com/rrrene/credo/issues

Analysis took 0.09 seconds (0.05s to load, 0.04s running 52 checks on 3 files)
4 mods/funs, found 1 warning.

Further Reading

Consider the following resource(s) to deepen your understanding of the topic.

• HexDocs: Credo

Mark As Completed

file_name = Path.basename(Regex.replace(~r/#.+/, __ENV__.file, ""), ".livemd")

save_name =
  case Path.basename(__DIR__) do
    "reading" -> "credo_reading"
    "exercises" -> "credo_exercise"
  end

progress_path = __DIR__ <> "/../progress.json"
existing_progress = File.read!(progress_path) |> Jason.decode!()

default = Map.get(existing_progress, save_name, false)

form =
  Kino.Control.form(
    [
      completed: input = Kino.Input.checkbox("Mark As Completed", default: default)
    ],
    report_changes: true
  )

Task.async(fn ->
  for %{data: %{completed: completed}} <- Kino.Control.stream(form) do
    File.write!(
      progress_path,
      Jason.encode!(Map.put(existing_progress, save_name, completed), pretty: true)
    )
  end
end)

form

Commit Your Progress

Run the following in your command line from the curriculum folder to track and save your progress in a Git commit. Ensure that you do not already have undesired or unrelated changes by running git status or by checking the source control tab in Visual Studio Code.

$ git checkout -b credo-reading
$ git add .
$ git commit -m "finish credo reading"
$ git push origin credo-reading

Create a pull request from your credo-reading branch to your solutions branch. Please do not create a pull request to the DockYard Academy repository as this will spam our PR tracker.

DockYard Academy Students Only:

Notify your teacher by including @BrooklinJazz in your PR description to get feedback. You (or your teacher) may merge your PR into your solutions branch after review.

If you are interested in joining the next academy cohort, sign up here to receive more news when it is available.

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