This assertion about all elements verifying a predicate is mentioned in the text but is not in the code example

To verify that a collection contains a specified number of elements and that all elements match a predicate.

IEnumerable numbers = new[] { 1, 2, 3 };
numbers.Should().HaveCount(4, "because we thought we put four items in the collection");

IMPORTANT

• The code complies with the Coding Guidelines for C#.
• The changes are covered by a new or existing set of unit tests which follow the Arrange-Act-Assert syntax such as is used in this example.
• If the contribution adds a feature or fixes a bug, please update the release notes, which are published on the website.
• If the contribution changes the public API the changes needs to be included by running AcceptApiChanges.ps1/AcceptApiChanges.sh.
• If the contribution affects the documentation, please include your changes in this pull request so the documentation will appear on the website.