Using akkurate for unit test assertions

[dave08]

// In the tests code base... not for validation, only for test assertions on the object hierarchy returned.
val validator = Validator<Book, Book> { expected ->
    // First the property, then the constraint, finally the message.
    title.isNotEmpty().isEqualsTo(expected.title)

    releaseDate.isEqualsTo(expected.releaseDate)

    authors.startsWith(expected.authors.take(3)) // This would be more useful for urls that's ports change in tests when mock servers go up with different random port...

   // Skip checking unimportant or volatile fields, or check inside the object hierarchy which wouldn't be possible with a normal assertEquals(...)
}

// Using Strikt for assertions, but something similar could be done for other frameworks...
expectThat(result).isValid(validator, expectedBook)

A validator by itself won't check the expected state of the resulting object... and the validator isn't the same as one that would validate an object's state in production, because in production you have certain requirements on the data of the object, whereas in tests you're just comparing a resulting state to an expected one (ignoring certain fields, or treating others in special ways for the comparison you're interested in for that particular set of tests...)

[nesk]

For those wondering, Dave and I had a reeeally long discussion about using Akkurate for test assertions (on Kotlin's Slack). This is an interesting use case but it's not the primary focus at the moment.

However, I would love to get more feedback about this. I you think this could be interesting and you're missing it, please describe your use case so we can discuss it furthermore and, eventually, plan something on the roadmap. ✍️