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Get Started Free →dotnet/generate-testability-wrappers
Generate wrapper interfaces and DI registration for hard-to-test static dependencies in C#, when the abstraction does NOT exist yet. Produces IFileSystem, IEnvironmentProvider, IConsole, IProcessRunner wrappers, or guides first-time adoption of TimeProvider and IHttpClientFactory. With no DI container, produces the ambient context seam instead. USE FOR: generate wrapper for static, create IFileSystem wrapper, wrap DateTime.Now, make a static or a class testable, create abstraction for File.*, ge
Passed 21 of 23 test cases with the skill, and 16 of 23 without it.
and 7 more in the full report
6 fixed15 passed either way1 still failing1 broke
Tokens, turns and time describe resource use, not a dollar price.
One of 6 test cases the skill fixed. Same model, same prompt, with and without the skill.
We have a C# 12 project targeting net8.0 where domain classes directly call DateTime.UtcNow. Create an abstraction and implementation so we can mock time in unit tests. We want to define a custom ISystemClock interface and SystemClock implementation.
| Checked | Without skill | With skill |
|---|---|---|
| Recommends TimeProvider instead of creating a custom clock interface | Missed | Passed |
| Registers TimeProvider.System in the dependency injection container | Missed | Passed |
The instructions your model reads when the skill loads.
Generate wrapper interfaces, default implementations, and DI service registration code for untestable static dependencies. For statics that already have .NET built-in abstractions (TimeProvider, IHttpClientFactory), guide adoption of the built-in. For statics without built-in alternatives, generate custom minimal wrappers.
detect-static-dependencies and identifying which statics to wrapTimeProvider (.NET 8+) or System.IO.AbstractionsEnvironment.*, Console.*, or Process.*detect-static-dependencies)migrate-static-to-wrapper)If the target already consumes an injected interface or built-in abstraction, stop: do not add a second wrapper, project, registration, or test around that seam.
A missing DI package does not by itself force an ambient seam. For an instantiable class, prefer constructor injection and compose it explicitly or show the requested registration. Use Step 5 when the API is static and its signatures must stay static, or when the user explicitly forbids caller construction/DI changes.
| Input | Required | Description |
|---|---|---|
| Static category | Yes | Which category: time, filesystem, environment, network, console, process |
| Target framework | Yes | The TargetFramework from .csproj (affects which built-in abstractions exist) |
| Composition | No | Existing DI framework, explicit/manual construction, or immutable static API |
| Namespace | No | Target namespace for generated wrapper code |
test cases passed, vs 16 / 23 without
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