Hey, I stumbled upon some interesting situation us...

# http4k

[DanielZ]

Hey,
I stumbled upon some interesting situation using Environment and lenses.
When running following test:

@Test
    fun `extract a list of domain ids from environment`() {
        data class MyDomainId(val value: String)

        val DOMAIN_ID by EnvironmentKey.csv(",")
            .map(
                { strings: List<String> -> strings.map(::MyDomainId) },
                { next -> next.map(MyDomainId::value) })
            .of()
            .required()


        val domainIds = listOf(MyDomainId("1"), MyDomainId("2"))
        val environment = Environment.defaults(DOMAIN_ID of domainIds)

        environment[DOMAIN_ID] shouldBe domainIds
    }

it ends up in

Missing elements from index 1
expected:<[MyDomainId(value=1), MyDomainId(value=2)]> but was:<[MyDomainId(value=1)]>
Expected :[MyDomainId(value=1), MyDomainId(value=2)]
Actual   :[MyDomainId(value=1)]
<Click to see difference>

io.kotest.assertions.AssertionFailedError: Missing elements from index 1

Replacing the delimiter in csv() to for example ":" makes the test pass.
My findings so far: it’s not the csv() part - this happens when I split the string by hand.

How can I use both type-safety of the lens and , as separator? Where is my misunderstanding?

[dave]

This is because the default separator for environment is a comma. if you want to have multiple values, you can probably use EnvironmentKey.value(MyDomainId.multi.required("")

[DanielZ]

Thanks for the hint 😄
I use now

val DOMAIN_ID by EnvironmentKey
            .map(::MyDomainId, MyDomainId::value)
            .multi
            .of()
            .required()