Swevo.AutoAssert 1.1.0

AutoAssert

Free, MIT-licensed fluent assertions for .NET. No commercial license required — ever.

Why AutoAssert?

Starting with v8, FluentAssertions requires a paid commercial license for use in commercial projects (via its Xceed partnership). AutoAssert provides the same fluent Should() syntax you already know, fully free and open source under MIT, for teams who don't want licensing fees attached to their test suite.

using AutoAssert;

result.Should().Be(42);
name.Should().NotBeNullOrEmpty();
items.Should().HaveCount(3);
action.Should().Throw<InvalidOperationException>().WithMessage("boom");

Install

dotnet add package Swevo.AutoAssert

Supported assertions

Every assertion accepts an optional because reasoning clause, matching the syntax you're used to:

result.Should().Be(42, "the answer should always be 42");

BeEquivalentTo

BeEquivalentTo performs deep structural comparison of public readable properties and public fields. It works for plain objects, nested object graphs, and collections of objects.

using AutoAssert;

var actual = new OrderDto
{
    Id = 42,
    Customer = new CustomerDto { Name = "Ada" },
    Lines = [new OrderLineDto { Sku = "ABC", Quantity = 2 }]
};

var expected = new
{
    Id = 42,
    Customer = new { Name = "Ada" },
    Lines = new[] { new { Sku = "ABC", Quantity = 2 } }
};

actual.Should().BeEquivalentTo(expected);

Current v1 scope:

• compares public readable properties and public fields recursively
• treats collections as order-independent by default
• uses value equality for primitives, strings, enums, dates, GUIDs, and other value types
• ignores extra public members on the actual value when the expected value has fewer members
• protects against infinite recursion on circular object graphs

Limitations versus FluentAssertions:

• no options API yet (Excluding, WithStrictOrdering, custom comparers, etc.)
• failure output stops at the first difference instead of producing a full diff
• this assertion uses reflection for member traversal, while most other assertions remain direct non-reflective checks

Design goals

• MIT licensed, forever. No commercial tier, no per-seat fees.
• Zero reflection where possible — most assertions are plain equality/comparison checks; BeEquivalentTo uses public-member traversal.
• AOT-safe — works with Native AOT test hosts.
• Framework agnostic — throws a plain AssertionFailedException, recognized as a failure by xUnit, NUnit, and MSTest alike.
• Familiar syntax — migrating from FluentAssertions should mostly be a find-and-replace of the using statement for the assertion types covered above.

💼 Need .NET consulting?

I'm the author of AutoAssert and a suite of compile-time source generators (AutoWire, AutoMap.Generator) and 28+ Polly v8 resilience packages. I'm available for consulting on Polly v8 resilience, Azure cloud architecture, and clean .NET design.

→ solidqualitysolutions.com · LinkedIn

Also by the same author

🌐 Full suite overview: swevo.github.io

License

MIT © Justin Bannister