Installation¶

Which packages to add¶

The common case is a test project that composes plain object graphs and composed test method parameters/theories. That's two packages — Compono plus whichever test-framework integration matches your test host:

dotnet add package Compono --prerelease
dotnet add package Compono.XunitV3 --prerelease
# or, for TUnit:
dotnet add package Compono.TUnit --prerelease

This tutorial's assertions (.Should(), throughout this site's own examples) come from AwesomeAssertions, not Compono itself — add it too if your project doesn't already reference an assertion library:

dotnet add package AwesomeAssertions

Add the rest of the ecosystem as your tests need it:

dotnet add package Compono.NSubstitute --prerelease   # automatic substitute composition
dotnet add package Compono.Bogus --prerelease         # semantic fake data (names, emails, ...)

Every package targets net8.0/net9.0/net10.0/net11.0. Until the first stable 1.0 release, every published version is a 0.x.y-preview.N prerelease — the --prerelease flag (or an explicit <PackageReference Version="0.x.y-preview.N" />) is required for dotnet add package/NuGet restore to pick it up at all, since a plain dotnet add package skips prerelease versions by default. See Package Guides for what each package is for and when to add it.

No other setup required¶

Compono embeds its source generator as a Roslyn analyzer inside its own package (analyzers/dotnet/cs) — adding the Compono PackageReference is the only step needed to enable source generation. There's no separate generator package to add, no nuget.config entry beyond your normal NuGet feed, and no MSBuild property required to opt in.

If your test project doesn't already reference an xUnit v3 (or TUnit) test host, Compono.XunitV3 (or Compono.TUnit) doesn't add one for you — each integrates with an existing test project, it doesn't create one.

Verify the install¶

A minimal smoke check once the packages are added:

using Compono;

var composer = Composer.Create();
var value = composer.Create<InstallationCheck>();

public sealed class InstallationCheck;

Use a plain user-defined type here, not a built-in one like int — a built-in type is satisfied by Compono's own built-in value provider without ever reaching generated construction, so it would compile and run even if the source generator/analyzer wasn't actually wired up. A custom type like InstallationCheck only composes successfully through a real generator-produced construction plan, so this check genuinely exercises the generator, not just the core package.

If this compiles and runs, the source generator is wired up correctly. Next, write your first composed theory.