Branch coverage incorrect when using elvis operator

[driessamyn]

Kover incorrectly reports a gap in branch coverage

Consider this class:

class KoverExample {
    private val map = mapOf<Int, () -> String>(
        1 to { "Fred" },
        2 to { "Joe" }
    )
    fun greeting(i: Int): String =
        map[i]
            ?.invoke()
            ?: throw IllegalStateException("No greeting for $i")
}

and these tests:

class KoverExampleTest {
    val koverExample = KoverExample()

    @Test
    fun `when index exists, greet`() {
        koverExample.greeting(1) shouldBe "Fred"
    }

    @Test
    fun `when index does not exist, throw`() {
        shouldThrow<IllegalStateException> {
            koverExample.greeting(-1)
        }
    }
}

Kover reports only 75% branch coverage, highlighting map[i] as not covered.

Expected behavior

Kover should report full coverage in this example, in my opinion, given there is no code path not exercised with the test.

Reproducer

See code above.

Reports

Environment

• Kover Gradle Plugin version: 0.9.1
• Gradle version: 8.12
• Kotlin project type: Kotlin/JVM
• Coverage Toolset (if customized in build script): Kove

[driessamyn]

What does the postponed label mean in this case?

Let me know if I can help.

[shanshin]

What does the postponed label mean in this case?

Hi,
please refer to #720.

We plan to switch to using the JaCoCo agent, work in this area has been suspended until the release of JaCoCo with support for inline functions.

[shanshin]

Closed due to the end of IntelliJ Agent development (#720) and the introduction of a new strategy for measuring of Kotlin code coverage (#746).

It is recommended to use JaCoCo, for this purpose it is enough to specify

kover {
    useJacoco("0.8.13")
}

in each project.

[driessamyn]

@shanshin , if it is recommended to use JaCoCo, what is the purpose of Kover?

I was hoping Kover would be correctly reporting coverage for Kotlin, where JaCoCo doesn.
I raised this issue with the JaCoCo team, for example: jacoco/jacoco#1921

[shanshin]

@shanshin , if it is recommended to use JaCoCo, what is the purpose of Kover?

In its current form, this is a trade-off, the two implementations have their drawbacks. We can recommend using the set of tools that gives a more correct result.

Looking ahead, we plan to use only the JaCoCo JVM agent. For our part, we are implementing report generation (to find more accurate coverage of Kotlin declarations) and integration with Kotlin Gradle Plugin (without separate plugin).