...
internal class YMowerPositionTest
{
...
    @Test
    fun `Should throw exception for invalid values` ()
    {
        assertThrows(InvalidMowerPositionException::class.java) {
            YMowerPosition.build(INVALID_POSITION)
        }
    }
}

import org.assertj.core.api.Assertions.assertThat
import org.junit.jupiter.api.Assertions.*
import kotlin.test.Test

private const val POSITION: Int = 4;
private const val MESSAGE: String = "Invalid Y position $POSITION. Only positive values are valid."

internal class InvalidMowerPositionExceptionTest
{
    @Test
    fun `Should be build with custom value`() {
        val exception = assertThrows(InvalidMowerPositionException::class.java) {
            throw InvalidMowerPositionException.withValue(POSITION)
        }

        assertThat(exception.message).isEqualTo(MESSAGE)
    }
}

class InvalidMowerPositionException private constructor (message: String? = null, cause: Throwable? = null) : Exception(message, cause) {
    companion object {
        private const val MESSAGE: String = "Invalid Y position %d. Only positive values are valid."

        @JvmStatic
        fun withValue(value: Int): InvalidMowerPositionException
        {
            return InvalidMowerPositionException(String.format(MESSAGE, value), null)
        }
    }
}