Feature request: Should be with predicate?

Before you file a bug, have you:

Description

I often come across functions that don’t exist, for instance "A".Should().BeUpperCase(), and I was wondering if it would make sense to have an overload that takes a Predicate<T> that determines the expectancy.

Complete minimal example reproducing the issue

// Arrange
string input = "MyString";

// Act
string actual = input.ToUpperInvariant();

Desired behavior:

// Arrange
string input = "MyString";

// Act
string actual = input.ToUpperInvariant();

// Assert
actual.Should().Be(actual => actual.All(ch => char.IsUpper(ch)));

[weitzhandler]

var expectation = new
{
    Some = new
    {
        Foo = 1
    },
    Other = new
    {
        Bar = 2
    }
};

// this will ignore `A.Some.Note` and `A.Other.OtherNote` as they are not present in `expectation`.

First of all Jonas, thanks for your nice comprehensive example. This comment is the missing bit I was unaware of. I didn’t know you can use anonymous types for verification, and I also thought it’ll fail if the properties do not match. That is a perfect solution. Thank you for your time and patience explaining all that.

[jnyrup]

Match is the assertion you’re looking for.

actual.Should().Match(actual => actual.All(ch => char.IsUpper(ch)));