Fluent Assertions 8.8 Release: New Features & Improvements.

Fluent Assertions continues to set the standard for expressive, readable .NET unit testing. With the 8.8 release, the library introduces key new features and refinements that further empower developers to write robust, maintainable, and insightful tests no matter their preferred test framework.

What’s New in 8.8?

Add Support for MSTest4

Contributed by @jnyrup in #3111, Fluent Assertions now offers seamless compatibility with MSTest4. This means teams adopting the latest MSTest framework can leverage all the expressive power of Fluent Assertions without workarounds or manual integration. The update ensures future-proof testing for .NET projects as MSTest evolves.

Improvements

Allow WithoutMessage for Should().Throw() and ThrowAsync() — by @dennisdoomen in #3100
Developers can now use WithoutMessage to ignore exception messages in both synchronous and asynchronous throw assertions. This is especially useful when exception text is variable or localized, allowing tests to focus on exception types and properties instead of brittle message strings.
Improve reporting of the differences between long strings — by @dennisdoomen in #3101
String comparison feedback is now much more actionable. When asserting equality between long strings, the output clearly highlights exactly where differences occur, making it faster to diagnose and fix test failures.
Allow customizing the equivalency behavior for BeXmlSerializable — by @logiclrd in #3107
Users can now fine-tune how XML serialization equivalency is evaluated. This is a big win for teams working with complex or custom XML structures, ensuring assertions are both precise and flexible.

Why It Matters

Each improvement in 8.8 reflects Fluent Assertions’ commitment to developer productivity and test clarity. With broader MSTest4 support, smarter string diagnostics, and more flexible assertion APIs, .NET teams can ship cleaner code with greater confidence.

Get Started

Upgrade to Fluent Assertions 8.8 via NuGet and check out the official documentation for usage examples and migration tips. For detailed change logs and contribution credits, visit the GitHub releases page.

Ready to Level Up Your Testing?

Try the new features in your next test suite and see the difference for yourself. For questions or feedback, join the discussion on the Fluent Assertions GitHub or reach out to the community on Gitter.

FAQ

Does 8.8 require any breaking changes?
No breaking changes are introduced; upgrading should be seamless for most projects.
Is MSTest4 support automatic?
Yes, just upgrade your NuGet package and start using MSTest4 as your test runner.
Where can I find migration guidance?
The official docs and GitHub releases provide step-by-step details.

Ready to modernize your .NET testing? Upgrade to Fluent Assertions 8.8 today and experience sharper, more maintainable tests.