テーマ： csharp

• .NETの依存性注入の慣習: ライフタイム、スコープ、captive dependencyの罠

  Microsoft.Extensions.DependencyInjectionは、`IServiceCollection`上にtransient・scoped・singletonのいずれかのライフタイムでサービスを登録し、公開コンストラクタを通じてそれらを注入する。文書化されたルールは、scopedなサービスをsingletonに注入しないこと、コンテナが生成したものはコンテナ自身に破棄させること、サービスロケーター的な呼び出しを避けること、そしてcaptive dependencyがリクエストをまたいで状態を漏らすのではなく起動時に失敗するようスコープの検証を行うことである。

  article · ja · unreviewed · 知識の基準日 2026-09-16

• Writing a unit test in JUnit 5 and xUnit.net: annotations, lifecycle and parameterised cases side by side

  JUnit Jupiter marks tests with @Test, runs @BeforeEach and @AfterEach around each one on a fresh instance by default, and drives data-driven cases with @ParameterizedTest plus a source annotation; xUnit.net uses [Fact], the constructor and IDisposable for per-test setup on a fresh instance, [Theory] with [InlineData] for cases, and fixtures for shared expensive context. Writing tests with the same shape in both keeps a polyglot team's conventions aligned.

  methodology · en · unreviewed · 知識の基準日 2026-09-16

• C# async/await pitfalls: sync-over-async, async void and ConfigureAwait

  The classic mistakes in C# asynchronous code are blocking on a Task with .Result, .Wait() or GetAwaiter().GetResult() (deadlocks under a single-threaded SynchronizationContext, thread-pool starvation on servers), async void methods whose exceptions cannot be caught, and misplacing ConfigureAwait(false), which belongs in general-purpose libraries and not in application code.

  article · en · unreviewed · 知識の基準日 2026-09-16

• Pinning NuGet dependencies: PackageReference, central package management and packages.lock.json

  NuGet resolves the lowest applicable version of each package at restore time, so a restore can drift when new versions or floating ranges appear; a repeatable build declares versions once in Directory.Packages.props, enables RestorePackagesWithLockFile so packages.lock.json records the full closure, commits the lock file for applications, and restores with --locked-mode in CI.

  methodology · en · unreviewed · 知識の基準日 2026-09-16

• Nullable reference types in C#: a compile-time contract, not a runtime check

  With <Nullable>enable</Nullable> the C# compiler treats string as non-nullable and string? as nullable, tracks the null-state of every expression and warns on mismatches; nothing changes at run time, string and string? are the same type, and the null-forgiving operator ! plus the nullable-analysis attributes ([NotNullWhen], [MemberNotNull]) are how you tell the compiler what it cannot infer.

  article · en · unreviewed · 知識の基準日 2026-09-16

機械可読： JSON