TDD Elixir Phoenix Notes

tdd-elixir-phoenix-notes.md

TDD Elixir Phoenix Notes

• Erlang => Elixir => Phoenix

• https://elixir-lang.org/crash-course.html

• All notes below Derived From Here.

  • It was helpful to learn about endpoints first from this article. My notes are here.
  • Versions --< Releases --< Features --< Feature Tests --< Units -< Unit Tests
  • Web-enabled gitpod environment per feature from this template.

Table of Contents

• Chapter 1: Introduction
• Chapter 2: The What, the Why, and the How
• Chapter 3: Setting Up
• Chapter 3b: Leveraging Gitpod Environments
• Chapter 4: Showing a List of Chat Rooms
• Chapter 5: Refactoring Our Work
• Chapter 6: Creating Rooms
• Chapter 7: Putting the Chat in Chat Rooms
• Chapter 8: Authentication
• Chapter 9: Creating Users
• Chapter 10: Adding Authors to Chat
• Chapter 11: Adding History to Rooms
• Chapter 12: Conclusion
• Appendix: Troubleshooting
• Page Top Link

Chapter 1: Introduction

• Test-driven is about our leveraging testing tools prior to coding, and to help guide our code quality.

• TDD and BDD are both helpful ways to define testign specs.

• Most good testing tools derive from the ruby language testing tools like rspec, cucumber, gherkin

• Link To Page Top

Chapter 2: The What, the Why, and the How

• Versions --< Releases --< Features --< Feature Tests --< Units -< Unit Tests
• BDD is outside-in approach.
• TDD is inside out approach.
• 

Chapter 3: Setting Up

• Setup checkpoints:
  • Install wallaby and other libraries. Test wallaby.
  • This chatter app does not have supervisor. That is unfortunate, but next app will have GenServer and Supervisor.
  • BBD => TDD => Larger Architectural Decisions ??

$ mix new chatter_sup --sup ; cd chatter_sup
$ mix test
$ TEST_FILE_PATH='test/chatter_sup_test.exs'
$ LINE_NUM=9
$ mix test ${TEST_FILE_PATH}:${LINE_NUM}

• We will use wallaby for driving browser interaction testing.

  • An alterative for this is hound.

• Setup Steps:

  • Do we need sup option or other libraries like: jason + plug_cowboy

  • Add the following line to mix.exs: {:wallaby, "~> 0.29.1", [runtime: false, only: :test]}

  • $ mix format

  • $ mix deps.get

  • Add the following lines to the end of test/test_helpers.exs:

    • {:ok, _} - Application.ensure_all_started(:wallaby)
    • Application.put_env(:wallaby, :base_url, ChatterWeb.Endpoint.url())

  • Make config/test.exs reflect the following:

import Config

config :chatter,
  server: true
  config :chatter, :sql_sandbox, true

import_config "#{config_env()}"

• Add this conditional to the top of lib/chatter_web/endpoint.ex

if Application.get_env(:chatter, :sql_sandbox) do
  plug Phoenix.Ecto.SQL.Sandbox
end

• We install ChromeDriver locally.

• Troubleshooting may include wallaby and/or chomedriver.

• Now we want to configure wallaby to use Chrome in config/test.exs: config :wallaby, driver: Wallaby.Chrome

• We should take a look at test/support/conn_case.ex

  • This allows us to aggregate common code for feature and controller tests.
  • We will be testing the view and the controllers. We would also like to test the model (later).

• We will see things like:

defmodule ChatterWeb.SomeControllerTest do
  use ChatterWeb.ConnCase, async: true
  test "[testName]: This is a test description.", %{conn: conn} do # Use conn in test.

• Below we create and implement test/support/feature_case.ex

defmodule ChatterWeb.FeatureCase do
  use ExUnit.CaseTemplate

  using do
    quote do
      use Wallaby.DSL
      alias ChatterWeb.Router.Helpers, as: Routes

      @endpoint ChatterWeb.Endpoint
    end
  end

  setup tags do
    :ok = Ecto.Adapters.SQL.Sandbox.checkout(Chatter.Repo)

    unless tags[:async] do
      Ecto.Adapters.SQL.Sandbox.omde(Chatter.Repo, {:shared, self()})
    end

  metadata = Phoenix.Ecto.SQL.Sandbox.metadata_for(Chatter.Repo, self())
  {:ok, session} = Wallaby.start_session(metadata: metadata)
  {:ok, session: session}
  end
end

• Now we can also do things like:

defmodule ChatterWeb.UserVisitsHomePage do
  use ChatterWeb.FeatureCase, async: true

  test "User visits homepage", %{session: session} do
    session
    |> visit("/")
    |> assert_has(Query.css(".title", text: "Welcome to Chatter!"))
  end
end

$ mix test test/chatter_web/features/user_visits_homepage_test.exs # Error: We expected 1, yet found 0.

# lib/chatter_web/router.ex
- get "/", PageController, :index
+ get "/", ChatRoomController, :index

Chapter 3b: Leveraging Gitpod Environments

• First we ensure that the above works and is clear.
• Then we port the working code above to gitpod, with excellent notes.
• Our first deployment target is heroku.
• We recommend reaching out to leverage the gitpod/heroku progress of others after working thru this doc.

Chapter 4: Showing a List of Chat Rooms

Chapter 5: Refactoring Our Work

Chapter 6: Creating Rooms

Chapter 7: Putting the Chat in Chat Rooms

Chapter 8: Authentication

Chapter 9: Creating Users

Chapter 10 Adding Authors to Chat

Chapter 11: Adding History to Rooms

Chapter 12: Conclusion

Chapter 13: Appendix: Troubleshooting