Can we write junit test cases in Kotlin for the Java classes in an android project?

I am looking forward to migrate a legacy project form Java to Kotlin, which apparently lacks unit test cases.

I wrote test cases in kotlin for a Util class which is written in Java, but when running it I am facing "Tests events were not received". After a lot of searching and trying various SO answers I am still not able to get pass through this.

If i write the same test cases in a Java class then all tests work as expected with a proper report.

Couple of things i wanted to mention:

• There are no build time errors and the build is successful.
• I am using junit:4.13.2
• Android Studio version is Dolphin | 2021.3.1 Patch 1
• The test class is under app/src/test/java
• Tried keeping it under app/src/test/kotlin too but doesn't work
• Tried adding below config under build.gradle but no luck.

testOptions {
        unitTests.all {
            it.useJUnitPlatform()
        }
    }

Trying all this I started wondering if this is doable or not.

Following steps worked for me

a) Add following in build.gradle at project root level in

> dependencies

classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:1.7.20"

b) Add kotlin plugin in build.gradle at your app level

apply plugin: 'kotlin-android'

c) Create a test class in your unit test package, make sure that name of class ends with Test. I tried with following name for classes

Named the class ends with Test

status
> Worked

import org.junit.Test
import org.junit.runner.RunWith
import org.junit.runners.JUnit4
import junit.framework.TestCase.assertEquals

@RunWith(JUnit4::class)
class Kotlin1KotlinTest {
    @Test
    fun test1() {
        val res = 1 + 1
        assertEquals(2, res)
    }
}

Named the class that does not ends with Test

status
> Not working

Got

> Test events were not received

import org.junit.Test
import org.junit.runner.RunWith
import org.junit.runners.JUnit4
import junit.framework.TestCase.assertEquals

@RunWith(JUnit4::class)
class Kotlin1 {
    @Test
    fun test1() {
        val res = 1 + 1
        assertEquals(2, res)
    }
}

here is an example of a simple application with java classes and kotlin tests.

Java class

Path: src/main/java/MyClass.java

public class MyClass {
    public int addNumbers(int a, int b) {
        System.out.println("Calculating...");
        return a + b;
    }
}

Kotlin test

Path: src/test/kotlin/MyClassTest.kt

import org.junit.jupiter.api.Test
import kotlin.test.assertEquals

class MyClassTest {

    @Test
    fun test() {
        assertEquals(3, MyClass().addNumbers(1, 2))
    }
}

Gradle file (Kotlin)

plugins {
    kotlin("jvm") version "1.8.21"
    id("java")
}

group = "com.example"
version = "1.0"

repositories {
    mavenCentral()
}

dependencies {
    // Зависимости для JUnit 5
    testImplementation("org.junit.jupiter:junit-jupiter-api:5.9.2")
    testRuntimeOnly("org.junit.jupiter:junit-jupiter-engine:5.9.2")

    // Зависимость для поддержки Kotlin в тестах
    testImplementation("org.jetbrains.kotlin:kotlin-test-junit:1.8.21")
}

tasks.test {
    useJUnitPlatform()
}

Project screen