Support for Swift Testing

[johanblumenberg]

• [x] I have read the CONTRIBUTING.

🚀 Describe the feature you'd like

Support for Swift Testing

Currently, Swift Testing is not supported. Validations like this does not cause tests to fail:

        then(custom).function(identifier: .match { !$0.isEmpty })
            .disambiguate(with: String.self)
            .called(times: >1)