Assert a failed effect with ZIO2 and zio-test - scala

Question

I am a beginner in the Scala / ZIO 2 world, and I am trying to write some tests for a simple service.
so I have this method:
def validate(id: String): ZIO[Any, Throwable, Unit] = {
if (id == "invalid-id") {
ZIO.fail("Invalid id")
}
}
I tried several things, but mainly I tried to use the isFailure or the fails assertions:
suite("My suite")(
test("When id is valid") { // This passes
for {
result <- validate("valid-id")
} yield assertTrue(result == ())
},
test("when id is not valid") {
for {
result <- validate("invalid-id")
} yield assertTrue(isFailure(result)) // This doesn't even compile
}
)
How can I test the failure case of an effect?
I am using:
Scala: "3.2.1"
zio: "2.0.4"
zio-test: "2.0.5"

Answer 1

There are multiple ways to assert that an effect has failed. The below example demonstrates the use of ZIO#exit and ZIO#flip.
import zio._
import zio.test._
object MySpec extends ZIOSpecDefault {
def validate(id: String): ZIO[Any, String, Unit] =
ZIO.cond(id != "invalid-id", (), "Invalid id")
def spec =
suite("My suite")(
test("when id is not valid 1") {
for {
result <- validate("invalid-id").exit
} yield assertTrue(
result == Exit.fail("Invalid id")
)
},
test("when id is not valid 2") {
for {
result <- validate("invalid-id").flip
} yield assertTrue(
result == "Invalid id"
)
}
)
}