Ktor testing

[charlee-dev]

What's recommended approach for testing graphql ktor server?

[dariuszkuc]

Hello 👋
It should be the same approach as with testing any other server. See https://ktor.io/docs/testing.html.

If you want to test your queries, you could also generate test client code and run them against your server.

[charlee-dev]

I'll share my solution. Hopefully, it may be useful for someone in the future.

My server stack - Expedia GraphQL, Ktor, and Kmongo for serving MongoDB, and Koin for DI.

Test class:

private fun authInputVariables(email: String = user1.email, password: String = password1): Map<String, Any?> =
    mapOf("authInput" to mapOf("email" to email, "password" to password))

@DisplayName("Authentication tests")
class AuthTests {
    @BeforeEach
    fun setup() {
        startKoin { modules(testModule) }
    }

    @AfterEach
    fun teardown() {
        stopKoin()
    }

    @Nested
    @DisplayName("SignIn")
    inner class SignInTests {
        private val signInMutation = "mutation SignIn(\$authInput: AuthInput!) { signIn(authInput: \$authInput) { token user { id displayName imageUrl }}}"

        @Test
        fun `Sing in with valid credentials should return data with AuthResponse`() = test(
            query = signInMutation,
            variables = authInputVariables(),
            assert = { data, errors ->
                data shouldBeEqualTo "{signIn={token=eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJpc3MiOiJ1c2VyMWlkIiwidXNlcklkIjoidXNlcjFpZCJ9.kCXAK1o68-_ViOdc5CDa0e8jzpFSplSmRv-yxk0fmS4, user={id=user1id, displayName=Adrian, imageUrl=image1}}}"
                assertNull(errors)
            }
        )

        @Test
        fun `Sing in with blank email should return error message`() = test(
            query = signInMutation,
            variables = authInputVariables(email = ""),
            assert = { data, errors ->
                data shouldBeEqualTo null
                errors?.first()?.message shouldBeEqualTo Constants.Messages.EMAIL_BLANK
            }
        )
    }
}

Test helper

val testModule = module {
    single { MockProvider.userRepository }
    single { MockProvider.taskRepository }
    single { MockProvider.commentRepository }
    singleOf(::JwtService)
    singleOf(::AuthService)
    singleOf(::TaskService)
    singleOf(::CommentService)
    singleOf(::UserService)
}

fun test(
    users: List<User> = listOf(user1, user2),
    tasks: List<Task> = listOf(task1, task2),
    comments: List<Comment> = listOf(comment1, comment2, comment3),
    query: String,
    operations: String? = null,
    variables: Map<String, Any?>? = null,
    extensions: Map<String, Any?>? = null,
    assert: suspend (data: String, errors: List<GraphQLServerError>?) -> Unit,
) {
    val userRepository: UserRepository by KoinJavaComponent.inject(UserRepository::class.java)
    val taskRepository: TaskRepository by KoinJavaComponent.inject(TaskRepository::class.java)
    val commentRepository: CommentRepository by KoinJavaComponent.inject(CommentRepository::class.java)

    val graphQLRequestHandler = GraphQLRequestHandler(getGraphQLObject()) // getGraphQLObject() the one like in the ktor sample

    testApplication {
        userRepository.populateDatabase(users) {
            taskRepository.populateDatabase(tasks) {
                commentRepository.populateDatabase(comments) {
                    val request = GraphQLRequest(query, operations, variables, extensions)
                    val response = graphQLRequestHandler.executeRequest(request) as GraphQLResponse<*>
                    assert(response.data.toString(), response.errors)
                }
            }
        }
    }
}

Running Mongo locally for test. Requires import from kmongo:
testImplementation("org.litote.kmongo:kmongo-core-tests:4.7.0")

object MockProvider {
    val userRepository = UserRepo.instance
    val taskRepository = TaskRepo.instance
    val commentRepository = CommentRepo.instance

    private object UserRepo : KMongoBaseTest<User>() {
        val instance = UserRepository(mongoClient)
    }

    private object TaskRepo : KMongoBaseTest<Task>() {
        val instance = TaskRepository(mongoClient)
    }

    private object CommentRepo : KMongoBaseTest<Comment>() {
        val instance = CommentRepository(mongoClient)
    }
}