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Elixir & Phoenix: Scalable Backend Development · レッスン

Phoenixアプリケーションの統合テスト

Phoenixのコントローラー、ビュー、チャネルをテストし、Webアプリケーションの各部分が連携して動作することを確認します。

「Phoenixアプリケーションの統合テスト」はCoddyKit上の無料Elixir & Phoenix: Scalable Backend Developmentレッスンです。 これはレッスン2/4です。 下記で完全なレッスンを無料で読むことができます。その後、ブラウザ内の組み込みコードエディタと24時間対応のAIチューターでハンズオン演習できます。 これはElixir & Phoenix: Scalable Backend Development学習パスの一部であり、ウェブとCoddyKitアプリ全体で進捗が同期されます。 Elixir & Phoenix: Scalable Backend Developmentコースには全4レッスンが含まれています。

このレッスンの一部はまだ翻訳されておらず、英語で表示されています。

Test Web App Interactions

Welcome to integration testing for Phoenix applications! While unit tests check individual components, integration tests ensure different parts of your web application work together seamlessly.

  • They simulate real user interactions.
  • They cover routes, controllers, views, and channels.
  • They build confidence that your app's main flows function correctly.

Simulating HTTP Requests

Phoenix.ConnTest is your primary tool for testing HTTP requests. It allows you to simulate requests (GET, POST, PUT, DELETE) to your Phoenix application without needing a live server.

We use functions like get/2, post/3, and put/3 to send requests and then assert on the resulting connection (conn).

defmodule MyPhoenixAppWeb.ExampleTest do
  use ExUnit.Case, async: true
  import Phoenix.ConnTest

  # Assume a simple router route: get "/hello", PageController, :hello
  # and PageController.hello renders a page with "Hello World"
  test "can get a simple page" do
    # Simulate a GET request to /hello
    conn = get("/hello")

    # Assert the HTTP status code
    assert conn.status == 200

    # Assert the response body contains "Hello World"
    assert html_response(conn, 200) =~ "Hello World"
  end
end

Testing GET Requests

GET requests are typically used to fetch data or display pages. When testing, you'll simulate the request and then assert on the response's status code and its content.

Use html_response/2 to extract the HTML body and assert against its content using pattern matching (=~).

defmodule MyPhoenixAppWeb.PostControllerTest do
  use ExUnit.Case, async: true
  import Phoenix.ConnTest

  # Assume we have a router route: get "/posts", PostController, :index
  # And PostController.index renders a list of posts including "My First Post"
  test "lists all posts on GET /posts" do
    # Simulate a request to the /posts endpoint
    conn = get("/posts")

    # Assert that the request was successful and contains expected content
    assert conn.status == 200
    assert html_response(conn, 200) =~ "<h1>All Posts</h1>"
    assert html_response(conn, 200) =~ "My First Post"
  end
end

Testing POST Requests

POST requests are often used for creating new resources or submitting form data. When testing, you'll pass parameters along with the request.

After a successful creation, controllers often redirect. Use redirected_to/1 to check the redirect path.

defmodule MyPhoenixAppWeb.PostControllerTest do
  use ExUnit.Case, async: true
  import Phoenix.ConnTest

  # Assume we have a router route: post "/posts", PostController, :create
  # This action creates a post and redirects to the index page.
  test "creates a new post on POST /posts" do
    post_params = %{"post" => %{"title" => "New Post", "body" => "Content"}}

    # Simulate a POST request with parameters
    conn = post("/posts", post_params)

    # Assert that a redirect occurred to the posts index
    assert redirected_to(conn) == "/posts"
  end
end

Asserting Rendered Content

It's crucial to verify that your views render the correct data and structure. html_response/2 allows you to get the rendered HTML as a string.

You can then use string assertions or regular expressions to check for specific text, HTML tags, or dynamic content.

defmodule MyPhoenixAppWeb.PageControllerTest do
  use ExUnit.Case, async: true
  import Phoenix.ConnTest

  # Assume get "/dashboard" renders a page with user information
  test "renders dashboard with user info" do
    # For this example, we simulate a simple GET (no session handling here)
    conn = get("/dashboard")

    assert conn.status == 200
    response_html = html_response(conn, 200)

    # Check for specific elements in the rendered HTML
    assert response_html =~ "<title>Dashboard</title>"
    assert response_html =~ "<span>Welcome, John Doe!</span>"
    assert response_html =~ ~r/Last Login: \d{4}-\d{2}-\d{2}/ # Regex for dynamic date
  end
end

Testing Redirects and Errors

Testing user flow is vital. Phoenix provides helpers to assert redirects and error responses:

  • assert_redirected_to(conn, path): Verifies a redirect to a specific path.
  • assert_error_sent(conn, status): Checks for an HTTP error status code.
  • json_response(conn, status): Extracts a JSON body from an API error.
defmodule MyPhoenixAppWeb.AuthControllerTest do
  use ExUnit.Case, async: true
  import Phoenix.ConnTest

  # Assume post "/login" redirects to /dashboard on success
  test "redirects after successful login" do
    login_params = %{"email" => "test@example.com", "password" => "password"}
    conn = post("/login", login_params)
    assert redirected_to(conn) == "/dashboard"
  end

  # Assume post "/register" sends a 400 error for invalid data
  test "sends 400 error for invalid registration" do
    invalid_params = %{"email" => "bad", "password" => "short"}
    conn = post("/register", invalid_params)
    assert conn.status == 400
    assert json_response(conn, 400) == %{"errors" => %{"email" => ["is invalid"]}}
  end
end

Simulating User Sessions

Many web applications rely on sessions to maintain state, like a logged-in user. In tests, you can manually manipulate the connection's session to simulate different user states.

Use build_conn/0 to create a fresh connection, then put_session/3 to add session data before making your request.

defmodule MyPhoenixAppWeb.SessionControllerTest do
  use ExUnit.Case, async: true
  import Phoenix.ConnTest

  # Assume get "/profile" requires a user_id in the session
  test "accesses profile with session data" do
    # Build a connection and add a user_id to its session
    conn = 
      build_conn()
      |> put_session(:user_id, 123)
      |> get("/profile")

    assert conn.status == 200
    assert html_response(conn, 200) =~ "User Profile for ID: 123"
  end

  test "redirects unauthenticated users" do
    # No session data means no authenticated user
    conn = get("/profile")
    assert redirected_to(conn) == "/login"
  end
end

Channel Testing Introduction

Phoenix Channels are for real-time communication using WebSockets. Integration tests for channels verify that clients can connect, join topics, send messages, and receive broadcasts correctly.

This is crucial for chat applications, live dashboards, and any feature requiring instant updates.

Connecting to a Channel

Phoenix.ChannelTest provides functions to simulate a client connecting to your WebSocket and joining specific channel topics. The main function you'll use is subscribe_and_join/3.

It returns {:ok, pid, socket}, where socket represents the client's connection to the channel.

defmodule MyPhoenixAppWeb.ChatChannelTest do
  use ExUnit.Case, async: true
  use Phoenix.ChannelTest

  # Assume MyPhoenixAppWeb.UserSocket is your main WebSocket module
  # and it handles joining a "room:lobby" channel.
  test "can join the lobby channel" do
    # Simulate a client connecting and joining "room:lobby" with no params
    {:ok, _pid, socket} = subscribe_and_join(MyPhoenixAppWeb.UserSocket, "room:lobby", %{})

    # Assert that the socket is connected to the correct topic
    assert socket.topic == "room:lobby"

    # You might also assert on assigns set during the join process
    # assert socket.assigns.user_id # If user_id is assigned on join
  end
end

Sending & Receiving Channel Messages

Once connected to a channel, you can test the message flow. Use push/3 to simulate a client sending a message to the server, and assert_broadcast/2 to verify that the server broadcasts messages back to the topic.

assert_reply/3 can check replies to specific client pushes.

defmodule MyPhoenixAppWeb.ChatChannelTest do
  use ExUnit.Case, async: true
  use Phoenix.ChannelTest

  # Assume MyPhoenixAppWeb.UserSocket handles "new_msg" events on "room:lobby"
  test "broadcasts messages to the lobby" do
    {:ok, _pid, socket} = subscribe_and_join(MyPhoenixAppWeb.UserSocket, "room:lobby", %{})

    # Simulate pushing a message from the client
    ref = push(socket, "new_msg", %{"body" => "Hello everyone!"})

    # Assert that the server replied 'ok' to the push
    assert_reply ref, :ok

    # Assert that a message was broadcasted back to the topic
    assert_broadcast "new_msg", %{"body" => "Hello everyone!"}
  end
end

Quick Check

Let's check your understanding of integration testing in Phoenix.

Recap: Integrated Confidence

You've learned how to write robust integration tests for your Phoenix applications!

  • We covered simulating HTTP requests using Phoenix.ConnTest.
  • You now know how to test GET and POST requests, assert rendered HTML, and verify redirects and errors.
  • We also explored testing real-time features with Phoenix.ChannelTest, simulating client connections and message flows.

By writing these tests, you gain confidence that your application's components work together as intended, leading to more stable and reliable web services!

よくある質問

「Phoenixアプリケーションの統合テスト」レッスンは無料ですか?

はい。「Phoenixアプリケーションの統合テスト」の完全なテキストはこのウェブで無料で読めます。インタラクティブに演習し(組み込みコードエディタと24時間対応のAIチューター)、Elixir & Phoenix: Scalable Backend Developmentコースの残りをアンロックするには、CoddyKit PROにアップグレードしてください。 Elixir & Phoenix: Scalable Backend Developmentコースには全4レッスンが含まれています。

「Phoenixアプリケーションの統合テスト」で何を学びますか?

Phoenixのコントローラー、ビュー、チャネルをテストし、Webアプリケーションの各部分が連携して動作することを確認します。 ブラウザで直接実行するハンズオンコードでElixir & Phoenix: Scalable Backend Developmentを演習し、24時間対応のAIチューターがレッスンを進める中での質問に答えます。

Elixir & Phoenix: Scalable Backend Developmentを始めるのに経験は必要ですか?

事前経験は必要ありません。CoddyKitのElixir & Phoenix: Scalable Backend Developmentは初級者から上級者向けに構成されているため、ここから始めるか最初から始めて、自分のペースで進むことができます。 これはレッスン2/4です。

「Phoenixアプリケーションの統合テスト」レッスンにはどのくらい時間がかかりますか?

ほとんどのCoddyKitレッスンは約5~10分かかります。各レッスンはコンパクトでインタラクティブなので、着実に進歩し、ウェブとアプリ全体で正確に前回の場所から再開できます。

このElixir & Phoenix: Scalable Backend Developmentレッスンでコードを書いて実行できますか?

はい。すべてのElixir & Phoenix: Scalable Backend Developmentレッスンに組み込みコードエディタが含まれているため、ブラウザでリアルコードを書いて実行し、即座のAIフィードバックを取得できます。ローカル設定は不要です。

このコースのすべてのレッスン

  1. ExUnitによる単体テスト
  2. Phoenixアプリケーションの統合テスト
  3. モック、スタブ、テストデータ
  4. StreamDataによるプロパティベーステスト
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