kotlin 권한 체크

Checkers.kt

interface EmailChecker {
    fun checkEmail(email: String): Boolean = email.contains("@")
}

interface RoleChecker {
    fun <T : Collection<String>> T.checkRole(role: String): Boolean = contains(role)
}

class FirstValidator {
    fun validate(value: String): Boolean = TODO()
}

class SecondValidator {
    fun validate(value: String): Boolean = TODO()
}

class ThirdValidator {
    fun validate(value: String): Boolean = TODO()
}

interface NicknameChecker {
    // 3rd party 의존성들
    val firstValidator: FirstValidator
    val secondValidator: SecondValidator
    val thirdValidator: ThirdValidator

    fun checkNickname(nickname: String): Boolean =
        firstValidator.validate(nickname) &&
                secondValidator.validate(nickname) &&
                thirdValidator.validate(nickname)
}

class NicknameCheckerImpl(
    override val firstValidator: FirstValidator,
    override val secondValidator: SecondValidator,
    override val thirdValidator: ThirdValidator
) : NicknameChecker

CheckersTest.kt

class CheckersTest : EmailChecker, RoleChecker, NicknameChecker {
    override val firstValidator: FirstValidator = mockk()
    override val secondValidator: SecondValidator = mockk()
    override val thirdValidator: ThirdValidator = mockk()

    @Test
    fun `이메일에 @가 포함되면 checkEmail() 호출시 true를 반환해야 한다`() {
        // given
        val email = "test@test.com"

        // when
        val actual = checkEmail(email)

        // then
        assertTrue(actual)
    }

    @Test
    fun `컬렉션에 해당 role이 포함되어 있으면 checkRole() 호출시 true를 반환해야 한다`() {
        // given
        val role = "something"
        val roles = setOf("foo", "bar", role)

        // when
        val actual = roles.checkRole(role)

        // then
        assertTrue(actual)
    }

    @Test
    fun `checkNickname() 호출시 FirstValidator#validate(), SecondValidator#validate(), ThirdValidator#validate() 함수가 호출되어야 한다`() {
        // given
        val nickname = "something"
        every { firstValidator.validate(nickname) } returns true
        every { secondValidator.validate(nickname) } returns true
        every { thirdValidator.validate(nickname) } returns true

        // when
        val actual = checkNickname(nickname)

        // then
        assertTrue(actual)
        verify { firstValidator.validate(nickname) }
        verify { secondValidator.validate(nickname) }
        verify { thirdValidator.validate(nickname) }
    }
}

UntestableUser.kt

open class Dependency {
    fun doSomething(dependency: Dependency) {}
}

class Dependency1 : Dependency()
class Dependency2 : Dependency()
class Dependency3 : Dependency()
class Dependency4 : Dependency()
class Dependency5 : Dependency()

data class UntestableUser(
    val dependency1: Dependency1,
    val dependency2: Dependency2,
    val dependency3: Dependency3,
    val dependency4: Dependency4,
    val dependency5: Dependency5,

    val email: String,
    val nickname: String,
    val roles: List<String> = listOf()
) {
    init {
        dependency2.doSomething(dependency1)
        dependency3.doSomething(dependency2)
        dependency4.doSomething(dependency3)
        dependency5.doSomething(dependency4)
    }
}

UserService.kt

class UserService(
    private val nicknameChecker: NicknameChecker
) : EmailChecker, RoleChecker, NicknameChecker by nicknameChecker {

    fun signOn(user: UntestableUser) {
        if (checkEmail(user.email)
            && user.roles.checkRole("something")
            && checkNickname(user.nickname)
        ) {
            // do something
        }
    }
}