mockPetsDao.kt

import org.h2.jdbcx.JdbcDataSource

fun PetsDao.Companion.mock(): PetsDao {
    val source = JdbcDataSource().apply {
        setURL("jdbc:h2:mem:${UUID.randomUUID()};MODE=MySQL;DB_CLOSE_DELAY=-1")
        this.user = "sa"
        this.password = ""

        connection.use { conn ->
            conn.prepareStatement("CREATE TABLE pets (id INT(64) PRIMARY KEY NOT NULL AUTO_INCREMENT, name TEXT NOT NULL)").executeUpdate()
            conn.prepareStatement("CREATE TABLE photos (id INT(64) PRIMARY KEY NOT NULL AUTO_INCREMENT, pet_id INT(64), url TEXT NOT NULL)").executeUpdate()
        }
    }
    return PetsDao(source)
}

PetsDaoTest.kt

class PetsDaoTest {

    private val testObj = PetsDao.mock()

    @Test
    fun `get missing`() {
        testObj[123] shouldBe null
    }

    @Test
    fun `create and get`() {
        val id = testObj.create("Tigger")
        testObj[id] shouldBe Pet(
            id = id,
            name = "Tigger",
            photoUrls = emptyList()
        )
    }
    
    @Test
    fun `add photo urls and get`() {
        val id = testObj.create("Tigger")
        testObj.addImage(id, "http://foo.jpg")
        testObj.addImage(id, "http://bar.jpg")

        testObj[id] shouldBe Pet(
            id = id,
            name = "Tigger",
            photoUrls = listOf("http://foo.jpg", "http://bar.jpg")
        )
    }
}