Reproducible builds in .NET replace file paths with placeholder values to enable reproducible builds and prevent leaking local development paths in binary outputs. This is a common practice on CI/CD pipelines. However, libraries that rely on actual file paths to function, like snapshot testing frameworks, face a challenge: they need to know where to store and load snapshot files on disk. This post… [read more]

Snapshot testing is a technique where the output of a function or component is serialized and saved to disk the first time the test runs. On every subsequent run, the library re-serializes the output and compares it against the saved file. If they differ, the test fails. Meziantou.Framework.SnapshotTesting is a .NET library that makes snapshot testing straightforward. It handles serialization, file… [read more]

Adding a Clone method to a C# record When using records, creating a copy with with is concise: var sample = new Sample("meziantou"); _ = sample with { }; public record Sample(string Value); This works well, but sample with { } is not always obvious as a discoverable Clone API for consumers. Why public Sample Clone() is not allowed Records already have compiler-generated clone behavior used by with.… [read more]

If you have a Rune and want its Unicode name (for example GRINNING FACE for 😀), there is no built-in API in .NET today. Here are two practical options: Use the ICU library available on the operating system Use the Meziantou.Framework.Unicode NuGet package Method 1: Use ICU from the OS ICU exposes u_charName, which returns the Unicode name for a code point. using System; using… [read more]

When creating reusable GitHub Actions workflows or composite actions, you often need to allow callers to provide extra arguments to a command. For example, a workflow that builds a .NET project might accept additional arguments for dotnet build. Handling these arguments safely requires careful attention to prevent script injection and ensure proper argument splitting. The problem with direct interpolation… [read more]

Pinning GitHub Actions to a full-length commit SHA is one of the simplest ways to reduce supply chain risk in your workflows. It ensures that a workflow keeps using the exact code you reviewed, instead of silently following a moving tag or branch. Tags are convenient, but they are mutable. A workflow that uses actions/checkout@v4 or a third-party action pinned to a tag can start running different code… [read more]

When people compare numbers, they usually expect a simple rule: same value means equal. For floating-point numbers (Half, float, and double), there are actually two useful notions of equality in .NET: IEEE comparison semantics, used by == equivalence semantics for .NET objects, used by Equals At first sight this looks inconsistent. In practice, each one solves a different problem. Quick behavior matrix… [read more]

You can insert newline characters in many URLs and browsers will still navigate correctly. At first glance, this looks invalid, but modern browser URL parsers are more permissive than most developers expect. This post continues a small series about HTML parsing surprises, like . Newlines in URLs can still work For example, this link works in browsers: <a href="https://example.com/docs/… [read more]

In a previous post, I explained how to generate the OpenAPI document during the ASP.NET Core build and commit it to the repository. That gives you a versioned API contract that is easy to review in pull requests. In this post, let's go one step further: use that generated OpenAPI file as the input for Kiota, so your typed .NET client is also generated during build. The goal is simple: The server produces… [read more]

When we talk about new lines, most developers think about \r\n (Windows) and \n (Unix-like systems). That works most of the time, but it is not the full picture. Unicode and several regex engines recognize additional line break characters. If your application parses user input, logs, CSV-like content, or cross-platform data, this can matter more than you think. The line breaks you should know The most… [read more]