How am I supposed to mock DB in tests using technologies mentioned in question? None of my solutions work.
The code below returns weird error:

database org.jetbrains.exposed.sql.Database@134ff8f8 don’t have any transaction manager

class UrlShortenerServiceTest : KoinTest {

private val testModule = module {
    single<Cache<String, String>> { mockk(relaxed = true) }
    single<Database> { mockk(relaxed = true) }
    single<TransactionManager> { mockk(relaxed = true) }
    single { UrlShortenerService(get(), get()) }
    single<TransactionManager> { mockk(relaxed = true) }

}

private val urlShortenerService: UrlShortenerService by inject()
private val mockCache: Cache<String, String> by inject()
private val mockDb: Database by inject()
private val mockTransactionManager: TransactionManager by inject()


@BeforeTest
fun setup() {
    startKoin {
        modules(testModule)
    }

}

@AfterTest
fun tearDown() {
    stopKoin()
}


@Test
fun `test url shortener `(){
    val longUrl = "http://www.test.com"

    val result = urlShortenerService.shortenUrl(longUrl)

    assertNotNull(result)
    assertFalse(result.isEmpty())

    verify { mockCache.put(any(), any()) }

    verify {
        transaction(mockDb) {
            UrlMapping.insert { any() }
        }
    }
}

I completely do not understand what is it and why it is not working. I suppose ChatGPT returned me some wrong code which was written by someone. WHat is a fix?