Hi, I'm new to Atrium (and Kotlin) so bear with me...

# atrium

[Igor Akkerman]

Hi, I'm new to Atrium (and Kotlin) so bear with me. I have a collection of objects and I want to make assertions on its content using some of the objects' properties. What I currently have is not readable. Is there a cleaner way?

data class Member(val name: String, val interest: String, val favoriteNumber: Int)
val members = listOf(Member("Me", "Kotlin", Random.nextInt()), Member("MyDog", "food", Random.nextInt()))
expect(members)
        .containsExactly(
                { feature { f(it::name) }.toBe("Me") ; feature { f(it::interest) }.toBe("Kotlin")},
                { feature { f(it::name) }.toBe("MyDog") ; feature { f(it::interest) }.toBe("food")}
        )

[robstoll]

Hi Igor, in case you use this combination name/interest often, then I would suggest you add a corresponding assertion function (maybe you can come up with a better name):

fun Expect<Member>.hasNameAndInterest(name: String, interest: String) =
    this.feature({ f(it::name) }, { toBe(name) })
        .feature({ f(it::interest) }) { toBe(interest) }

then it can be rewritten to:

expect(members).containsExactly(
    { hasNameAndInterest("Me", "Kotlin") },
    { hasNameAndInterest("MyDog", "food") }
)

[robstoll]

In case toBe was only an example and you want to perform other assertions on the properties, e.g. startsWith("Kot") then you could provide a shortcut for the properties:

val Expect<Member>.name
    get() = name(this).getExpectOfFeature()

// allows to define an assertion group for the feature
fun Expect<Member>.name(assertionCreator: Expect<String>.() -> Unit) =
    name(this).addToInitial(assertionCreator)

private fun name(expect: Expect<Member>) = ExpectImpl.feature.property(expect, Member::name)

Whether this boilerplate is worth it depends on how many times you use the property IMO. Then you could use it as follows:

expect(members).containsExactly(
    { name.toBe("Me") },
    { name { startsWith("Ro"); endsWith("t") } }
)

[robstoll]

@Igor Akkerman I hope that helps, otherwise let me know

[Igor Akkerman]

Hi Robert, thanks a lot for your help. I'm really a fan of the flexibility of Atrium and the expressiveness of the assertion code and especially of the output in case of test failure.

Might there be a way on the side of the library to make the latter version require less boilerplate, generalizing assertions on properties? From AssertJ, I remember it allowing to specify fields to do comparisons on. It was using the field names as Strings, though.

I noticed a tiny irregularity:
While the assertion works correctly, in entry 1, the output shows "name" as "Me", while the object has "MyDog". Could the assertion have cached the value in a wrong way?

ch.tutteli.atrium.reporting.AtriumError: expect: [Member(name=Me, interest=Kotlin, favoriteNumber=1771517067), Member(name=MyDog, interest=food, favoriteNumber=-1574926733)] (java.util.Arrays.ArrayList <1682681674>)
◆ contains only, in order:
✔️ ▶️ entry 0: Member(name=Me, interest=Kotlin, favoriteNumber=1771517067) (atriumtest.AtriumTest.Member <613298587>)
◾ an entry which:
» ▶️ name: "Me" <1446983876>
◾ to be: "Me" <1446983876>
» ▶️ interest: "Kotlin" <1042790962>
◾ to be: "Kotlin" <1042790962>
✘ ▶️ entry 1: Member(name=MyDog, interest=food, favoriteNumber=-1574926733) (atriumtest.AtriumTest.Member <2130192211>)
◾ an entry which:
» ▶️ name: "Me" <1446983876>
◾ to be: "MyDog" <990897274>
» ▶️ interest: "Kotlin" <1042790962>
◾ to be: "foodX" <539690370>
✔️ ▶️ size: 2 (kotlin.Int <593415583>)
◾ to be: 2 (kotlin.Int <593415583>)

[robstoll]

do you mean simplifying feature { f(it::name) } ?

[robstoll]

or are you talking about something in the output?

[robstoll]

what would you like to see?

[robstoll]

ah... forget what I just wrote 😄 I missed the I noticed a tiny irregularity

[Igor Akkerman]

You didn't miss it, I hit enter to quickly and edited the original message 😉

[robstoll]

ah ok

[Igor Akkerman]

Yes, I meant simplifying feature { f(it::name) }

[robstoll]

the irregularity is actually a bug I have on my radar for a longer time (planned for 0.10.0 now, see roadmap https://github.com/robstoll/atrium#0100). You are the first noticing/reporting it though

[robstoll]

Atrium should not show the value at all in, it should be as follows:

an entry which:
>> name:
  - to be: "My Dog"

[Igor Akkerman]

Actually, it's better if it shows the actual value alongside the expected value, so you see the diff immediately

[robstoll]

regarding simplifying feature it is mainly that complicated because Kotlin has unfortunately many bugs in the area of type inference and method overloading. See the list here https://github.com/robstoll/atrium#kotlin-bugs, would be nice if you can upvote some, so jetbrains invests a bit more time in this area

[robstoll]

you are right, it could be shown for in order only , it would not make sense for in any order .

[Igor Akkerman]

True

[robstoll]

good input, I would have removed it for all functions, I'll keep that in mind

[Igor Akkerman]

Great, thanks

[robstoll]

you could also write feature(Member::name) in case you find that simpler

[robstoll]

see also https://github.com/robstoll/atrium-roadmap/issues/21 maybe you can comment there regarding your use case

[Igor Akkerman]

ah missed that one, that's perfectly readable/writable then

[Igor Akkerman]

awesome

[Igor Akkerman]

I believe feature(Member::name) is good enough, really. No idea if something like containsExactly({Member::name toBe "Me"; Member::interest toBe "Kotlin"}) would be technically possible

[Igor Akkerman]

To me, comparing data classes by showing their toString() diff is perfectly fine

[Igor Akkerman]

I added a comment to https://github.com/robstoll/atrium-roadmap/issues/21