NUnit vs AVA

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

Widely used

.NET Foundation · since 2002

Established

OSS community · since 2015

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

• Process isolation catches hidden coupling between tests that other runners hide.
• Concurrent by default, so suites stay fast without configuration.
• Clean, small API with no magic globals.

• 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.

• No DOM environment; not for front-end work.
• No built-in mocking or snapshots comparable to Jest.
• Smaller community than the mainstream runners.

Existing .NET codebases already standardised on NUnit.

Node libraries where test isolation and speed matter more than ecosystem breadth.