AssertJ: Type inference failed: Not enough information to infer parameter T in org.assertj.core.api.Assertions.fail

Question

In a pure Kotlin project I am using JUnit Jupiter 5.5.2 and AssertJ 3.10.0. The following test executes successful:

@Test
fun `Validates something`() = runBlocking {
    try {
        // Assert something
    } catch (t: Throwable) {
        fail("Should not throw $t")
    }
}

Once I update to AssertJ 3.11.1 the test build fails with this message:

Type inference failed: Not enough information to infer parameter T in fun fail(p0: String!): T!
Please specify it explicitly.

If I use fail<Nothing>("Should not throw $t") then No test were found.

I tried to figure out what's going on - without success though.

Related

• JUnit5 issue #1209: Can't call "fail" in Kotlin without specifying generic type explicitly

Answer 1

It seems the problem is with the runBlocking expression body. If you turn it into a block body, then it would work no matter which type you use to specify on the fail method (using Nothing as an example, which can be Any, Any? or any other types):

@Test
fun `Validates something`() {
    runBlocking {
        try {
            // Assert something
        } catch (t: Throwable) {
            fail<Nothing>("Should not throw $t")
        }
    }
}