xUnit.net vs NUnit

Free and open source

Free and open source

Free and open source. You pay in engineering time and CI minutes.

Free and open source. You pay in engineering time and CI minutes.

Everything, self-hosted

Everything, self-hosted

Category standard

.NET Foundation · since 2007

Widely used

.NET Foundation · since 2002

• Per-test instance isolation eliminates a whole class of shared-state bugs by design.
• Idiomatic modern C# — no attribute soup.
• The default in current .NET project templates.

• The most expressive built-in assertion library in .NET.
• Familiar attribute model for teams migrating from older frameworks.
• Very stable, very long-lived.

• Fewer built-in assertions than NUnit; most teams add FluentAssertions.
• The isolation model surprises developers migrating from NUnit.
• Parallelism defaults occasionally bite on integration tests.

• Shared test-class instances mean state can leak between tests unless you are careful.
• New Microsoft templates default to xUnit, so it is drifting from the mainstream.
• Attribute-heavy style feels dated.

New .NET projects.

Existing .NET codebases already standardised on NUnit.