---
title: Overview
description: Third-party test frameworks and libraries that AutoFixture integrates with.
---

AutoFixture ships extension packages that connect to tools you already use in .NET test projects. Each guide below covers the third-party library, what AutoFixture adds, and how to install both sides.

Pick the test framework you use, then add a mocking library if your tests need substitutes for interfaces or abstract types.

## Test frameworks

These libraries run your tests. AutoFixture extensions add data attributes so method parameters become anonymous specimens (`[AutoData]` / `[InlineAutoData]` on xUnit and NUnit; `[AutoDataSource]` / `[AutoArguments]` on TUnit).

- [xUnit.net 3](/docs/integrations/xunit3) — AutoFixture 5
- [NUnit 4](/docs/integrations/nunit4) — AutoFixture 5
- [TUnit](/docs/integrations/tunit) — AutoFixture 4 (preview)

## Mocking libraries

These libraries create test doubles. AutoFixture extensions register them as residue collectors so interfaces and abstract dependencies resolve to mocks, fakes, or substitutes when AutoFixture builds object graphs.

- [Moq](/docs/integrations/automoq)
- [NSubstitute](/docs/integrations/autonsubstitute)
- [FakeItEasy](/docs/integrations/autofakeiteasy)

## Related

- [Custom AutoData attribute](/docs/integrations/xunit3#custom-autodata-attribute) — share fixture setup (for example AutoMoq) across xUnit.net 3 theories
- [NUnit 4 custom attributes](/docs/integrations/nunit4#custom-autodata-attribute) — the same pattern for NUnit 4 tests
- [TUnit custom AutoDataSource](/docs/integrations/tunit#custom-autodatasource-attribute) — the same pattern for TUnit tests
- [AutoFixture integration packages](/docs/reference/packages) — NuGet packages that wrap the libraries above
- [v4 to v5 migration](/docs/reference/v4-to-v5-migration) — map older xUnit.net and NUnit integration packages to v5
- [FAQ](/docs/reference/faq) — interfaces, Freeze, AutoData, and other common failures