What do I do to make kotest print stacktrace with ...

# kotest

[Kirill Zhukov]

What do I do to make kotest print stacktrace with the root cause of the assertion error? 🧵

[Kirill Zhukov]

My test looks like this:

Untitled.kt

[Kirill Zhukov]

I have a proper assertion failure at requestMessage.shouldBeEqual based on an implementation change, but the stacktrace doesn't include the actual call where the assertion failed, why?

[Kirill Zhukov]

I get a stacktrace like this leading to nowhere...

Untitled.kt

[CLOVIS]

Hey, this is just how coroutines work… You may be interested in https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-debug/ and https://github.com/Kotlin/kotlinx.coroutines/blob/master/docs/topics/debugging.md

[Kirill Zhukov]

Not sure I understand where coroutines are involved here in my assertion?

requestMessage.shouldBeEqual("...")

Is the failing assertion, requestMessage is a String.

Or are you saying that's just how all kotest failure look like because test are using coroutines?

[sam]

The latter yes. All tests in Kotest run inside a coroutine.

[Klitos Kyriacou]

It sounds like the problem is due to some toString() method that turns HttpMethod(value=POST) into just "POST". That seems to be the only difference. By the way, what is shouldBeEqual? It doesn't seem to be part of Kotest.

[Kirill Zhukov]

shouldBeEqual is a kotest matcher

[Kirill Zhukov]

In my example requestMessage is a String , so I'm basically doing someString.shouldBeEqual(otherString)

[Klitos Kyriacou]

That's strange, I can see that it does indeed exist, but it doesn't appear to be documented (except as a prefix to the function named shouldBeEqualComparingTo) and I've always tested for equality using the shorter name shouldBe. Also, it sounds ungrammatical: "a shouldBeEqual b" doesn't sound like proper English; it should be either "a shouldEqual b" or "a shouldBeEqualTo b".

[Kirill Zhukov]

https://github.com/kotest/kotest/blob/2f9215c2f0519e08fe94ee6b37431fde736c1424/kot[…]/src/commonMain/kotlin/io/kotest/matchers/equals/shouldEqual.kt

[sam]

should be equal doesn't special case, it literally uses the equals method

[sam]

but shouldBe will take into account things like arrays

[Kirill Zhukov]

Anything can be done here to produce a normal stacktrace without having to hook up a bunch of debugging tooling?

[CLOVIS]

If you add

try {
    ...
} catch (e: Exception) {
    throw RuntimeException("Spied exception", e)
}

it'll ensure that at least that specific place appears in the stacktrace.

[CLOVIS]

Using kotlinx-coroutines-debug should just mean adding the dependency and running with -ea though, it shouldn't be too hard