If kotlin package has multiple main function, how can I call specific one?

Question

I want to test the main function for competitive programming.

Kotlin can have multiple main functions, however how to call specific one?
In other words, how to specify a function in the specific file?

Answer 1

As workaround, In JVM, in tests, we can create Java class which delegates calls to target main functions.

This is based on the fact that by default FileName.kt translates into Java class FileNameKt

public final class Mains {

    public static void section01() {
        Section01Kt.main();
    }

    public static void section02() {
        Section02Kt.main();
    }
}

Then use wrapper method in tests:

    @Test 
    fun testMain() {
        Mains.section01() // instead of main()
    }

Answer 2

It depends on compilation and execution tools:

• When you call "java -jar my-app.jar", JVM looks into the manifest file to find main class name.
• If you compile application with Gradle, you can define mainClassName as part of application plugin (which created executable jar).
• Maven tool has property for the main class too.
• IntelliJ Idea has independent settings, so you can specify multiple build configuration with different parameters. And you can put entry point there.