[Bug]: Overload resolution on string members prefers equality of IEnumerable<char> over string

[Ilia-Kosenkov]

Description

I stumbled upon this issue while adopting TUnit. If I am asserting an object to have a member of type string equal to something, using .Member() syntax for chaining, the overload resolution fails to pick up string comparison, favouring IEnumerable<char>. This triggers TUnitAssrtions0016 warning.

Expected Behavior

.IsEqualTo<string>(string) is preferred over .IsEqualTo<IEnumerable<char>>()

Actual Behavior

The opposite happens, which forces us to spell out .IsEuqualTo<string>(expectation).
This, however, does not happen with plain asserts over strings, e.g.

await Assert.That(@string).IsEqualTo(expectation);

correctly uses string overload.

Steps to Reproduce

var value = KeyValuePair.Create<string, object?>("error", null);

await Assert.That(value).Member(kvp => kvp.Key, key => key.IsEqualTo("error"));

TUnit Version

1.37.36

.NET Version

.NET 10

Operating System

Windows

IDE / Test Runner

JetBrains Rider

Error Output / Stack Trace

Additional Context

No response

IDE-Specific Issue?

• I've confirmed this issue occurs when running via dotnet test or dotnet run, not just in my IDE