nsubstitute/NSubstitute

Health v2 · maintenance only

Flags: no_license

Adoption not part of the score

2972 stars · 282 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-30, confidence not recorded

NSubstitute is a mocking library for .NET that generates substitute instances for interfaces and virtual members with a succinct, natural syntax. It focuses on Arrange-Act-Assert testing, letting developers set return values, check received calls, and raise events with minimal configuration noise.

Use cases

• mock dependencies in .NET unit tests
• create stubs for interfaces in C# tests
• verify a method was called with specific arguments
• set return values for test doubles
• raise events on mocked objects in tests
• learn test-driven development with an easy mocking library

When to choose

• you want a simple, readable mocking API with less boilerplate than Moq or Rhino Mocks
• your tests follow the Arrange-Act-Assert pattern
• you are new to unit testing and want a low-friction mocking library
• you only need to mock interfaces or virtual members

When to avoid

• you need to mock non-virtual members or static methods
• you require advanced features like partial mocking of complex class internals
• your project is not on the .NET platform

Facets

library · maturity stable

testing mocking testing developer-tools dotnet test-doubles stubs fakes arrange-act-assert c-sharp nuget

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