shouldBe does not handle java long or Long but does handle Integer

Getting a unexpected assertion failure while converting assertj assertions to kotlin-test shouldBe style assertions.

Given this simple Java class:

public class Foo {
    public static final long MEANING_OF_LIFE = 42l;
}

This test fails with the above on the shouldBe line:

import io.kotlintest.shouldBe
import org.assertj.core.api.Assertions
import org.junit.jupiter.api.Test

class FooTest {
    @Test
    fun fooTest() {
        val v1: Int = Foo.MEANING_OF_LIFE.toInt()
        val v2 = java.lang.Integer.valueOf(42)
        val v3 = Foo.MEANING_OF_LIFE
        val v4 = java.lang.Long.valueOf(42)
        val v5 = Foo.MEANING_OF_LIFE.toLong()

        // assertj works for all cases
        Assertions.assertThat(v1).isEqualTo(42)
        Assertions.assertThat(v2).isEqualTo(42)
        Assertions.assertThat(v3).isEqualTo(42)
        Assertions.assertThat(v4).isEqualTo(42)
        Assertions.assertThat(v5).isEqualTo(42)

        // works
        v1 shouldBe 42
        // works
        v2 shouldBe 42
        // fails
        v3 shouldBe 42
        // fails
        v4 shouldBe 42
        // fails
        v5 shouldBe 42
    }
}

with:

java.lang.AssertionError: expected: 42 but was: 42
Expected :42 
Actual   :42

So, it seems the only way I can make this work is calling toInt(). This seems to result from differences in the way kotlin numeric types differ from Java as explained here: https://kotlinlang.org/docs/reference/basic-types.html. But it makes testing Java code with Kotlin a bit more challenging. So, it might be worth investigating some kind of workaround and make shouldBe a bit more foregiving by maybe handling java primitive and boxed type explicitly.

[sksamuel]

I’ve added a quick fix and some tests. Basically I promote ints to longs, and floats to doubles where appropriate.

See https://github.com/kotlintest/kotlintest/commit/48182db19c1d27b18c112165d7247a95addd3c0a

[sksamuel]

Fix is applied in latest release 3.1.5