April 2022
Beginner to intermediate
464 pages
6h 44m
Japanese
Content preview from 実用 Go言語 ―システム開発の現場で知っておきたいアドバイス
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13.4 ヘルパー関数
テストを実行する際に、共通する処理を行うヘルパー関数を準備するのは一般的な手法です。ヘルパー関数内が t *testing.T の引数を取る場合は、 t.Helper() を呼ぶようにすると、テスト失敗時にノイズとなるようなヘルパー関数の情報が減り、メッセージがわかりやすくなります。もう1つの注意点は、テスト用のヘルパー関数をプロダクションコード（プロダクトとして実際に動作するコード）のビルドに含ませないように気をつけることです。テスト用のヘルパー関数は以下の2つの方法のいずれかで提供させます。
13.4.1 ヘルパー関数を_test.goというテストコードの中に書く
ファイルの末尾が _test.go であればビルドからは除外されるため、この特性を利用した手法です。もっともシンプルで一般的ですが、テストコードは他のパッケージからimportできないため、複数パッケージを横断したヘルパー関数の扱いには適しません。ファイル名は helper_test.go や パッケージ名_helper_test.go などがよく使われます。
13.4.2 テストヘルパー用のパッケージを作成する
testutil や testonly といった名称でテストコードとは別パッケージを作成し、 _test.go が末尾に付かない通常のGoファイルでヘルパー関数を定義します。この時、テストコードからしかimportしなければ、プロダクションコードのビルドには含まれないため問題にはなりません。この方法だと複数のパッケージにまたがる共通的なヘルパー関数を扱うことができます。あるパッケージの機能をモックするようなヘルパーの場合は、 パッケージ名test といった名称も良く見かけます。 ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.