Adds four missing assertion capabilities needed for projects working with numeric comparisons, enumerable containment, and async code.

New: FloatingPointAssertions<T> (IFloatingPoint<T> constrained)

float and double now get a dedicated assertions type via Should():

result.Reward.Should().BeApproximately(17.5, 0.1);
result.Reward.Should().BeGreaterThanOrEqualTo(0.0, 1e-10);
fileInfo.Length.Should().BeGreaterThan(0L); // integers use IntegerAssertions (no precision)

• BeApproximately(T expected, T precision) — asserts |value − expected| ≤ precision
• BeLessThan(T expected, T precision) — asserts value < expected - precision
• BeLessThanOrEqualTo(T expected, T precision) — asserts value <= expected + precision
• BeGreaterThan(T expected, T precision) — asserts value > expected + precision
• BeGreaterThanOrEqualTo(T expected, T precision) — asserts value >= expected - precision
• FloatingPointAssertionsChain<T> for .And chaining

All comparison methods require an explicit precision parameter (consistent with BeApproximately). Error messages include the precision, e.g. "Value should be less than 5 (±0.001) but was 5." The strict (BeLessThan, BeGreaterThan) and inclusive (BeLessThanOrEqualTo, BeGreaterThanOrEqualTo) methods form proper complement pairs.

Numeric comparisons on IntegerAssertions<T>

BeLessThan(T expected), BeLessThanOrEqualTo(T expected), BeGreaterThan(T expected), BeGreaterThanOrEqualTo(T expected) added — leverages the existing IBinaryInteger<T> constraint's IComparisonOperators.

Contain on EnumerableAssertions<TEnumerable, T>

results.Should().Contain(expectedItem);

Asserts the enumerable contains a specific item; throws "Value should contain {expected} but did not." on failure.

New: AsyncActionAssertions for Func<Task>

Async delegates now have a dedicated assertions type via Should(), mirroring the existing ActionAssertions API:

await multiEnvironment.Awaiting(m => m.StopAsync()).Should().ThrowAsync<SomeException>("expected message");
await service.Awaiting(s => s.StartAsync()).Should().NotThrowAsync();

• ThrowAsync<TException>() — asserts the async action throws the specified exception type, returns Task<ActionAssertionsChain<TException>>
• ThrowAsync<TException>(string expectedMessage) — with message check
• NotThrowAsync() — asserts the async action does not throw

InvokingExtensions gains Awaiting<T>(this T value, Func<T, Task> action) and Awaiting<T, TResult>(this T value, Func<T, Task<TResult>> action) for wrapping async methods on a value for assertion testing.

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.