Ordering assertions in CollectionAssertions should use IComparer, not IComparer<object>

Description

The ordering assertions in CollectionAssertions expect an IComparer<object>, although the declared type of the items in the collection does not need to be object. This makes it hard to use standard comparers such as StringComparer and comparers derived from Comparer<T>.

Complete minimal example reproducing the issue

The following does not compile:

string[] actual = { "a", "b", "c" };
actual.Should().BeInAscendingOrder(StringComparer.CurrentCultureIgnoreCase);

Expected behavior:

• You should be able to use a comparer that implements IComparer<T> for a generic collection with items of type T.
• You should be able to use a comparer that implements IComparer for a non-generic collection.

Actual behavior:

Does not compile.

Versions

• Which version of Fluent Assertions are you using? v5.6.0
• Which .NET runtime and version are you targeting? .NET framework 4.6.1

[dennisdoomen]

True, but technically that would be a breaking change.

[jnyrup]

No worries, I’ve been confused about that before as well.

For some future major release I hope we can overhaul the collection assertions more.