infinity money bug :D

This is here to show a small miss with big problems.

- add missing test to
  - TransactionEndpoints
  - TransactionControllerTest
- update Transfer with validation for sender receiver
- add SenderReceiverValidator
- add SenderReceiver

build.gradle.kts

@@ -26,6 +26,11 @@ dependencies {
     testImplementation(aa.springboot.starter.test)
 
     testRuntimeOnly(aa.junit.platform.launcher)
+
+    testIntegrationImplementation(aa.library.test.integration)
+    testIntegrationImplementation(aa.springboot.starter.test)
+
+    testIntegrationRuntimeOnly(aa.junit.platform.launcher)
 }
 
 group = "ltd.lulz"

http/transaction.http

@@ -0,0 +1,27 @@
+### Deposit
+POST {{url}}/deposit
+Content-Type: application/json
+
+{
+    "account": "00000000-0000-0000-0000-000000000000",
+    "amount": 1.23
+}
+
+### Withdrawal
+POST {{url}}/withdrawal
+Content-Type: application/json
+
+{
+  "account": "00000000-0000-0000-0000-000000000000",
+  "amount": 1
+}
+
+### Withdrawal
+POST {{url}}/transfer
+Content-Type: application/json
+
+{
+  "account": "00000000-0000-0000-0000-000000000000",
+  "receiver": "00000000-0000-0000-0000-000000000000",
+  "amount": 1
+}

src/main/kotlin/ltd/lulz/annotation/SenderReceiver.kt

@@ -0,0 +1,15 @@
+package ltd.lulz.annotation
+
+import jakarta.validation.Constraint
+import jakarta.validation.Payload
+import kotlin.reflect.KClass
+import ltd.lulz.annotation.validator.SenderReceiverValidator
+
+@Constraint(validatedBy = [SenderReceiverValidator::class])
+@Target(AnnotationTarget.CLASS)
+@Retention(AnnotationRetention.RUNTIME)
+annotation class SenderReceiver(
+    val message: String = "Receiver and Sender cant be the same account",
+    val groups: Array<KClass<*>> = [],
+    val payload: Array<KClass<out Payload>> = [],
+)

src/main/kotlin/ltd/lulz/annotation/validator/SenderReceiverValidator.kt

@@ -0,0 +1,14 @@
+package ltd.lulz.annotation.validator
+
+import jakarta.validation.ConstraintValidator
+import jakarta.validation.ConstraintValidatorContext
+import ltd.lulz.annotation.SenderReceiver
+import ltd.lulz.model.Transfer.Request
+
+class SenderReceiverValidator : ConstraintValidator<SenderReceiver, Request> {
+
+    override fun isValid(
+        request: Request,
+        context: ConstraintValidatorContext,
+    ): Boolean = request.receiver != request.account
+}

src/main/kotlin/ltd/lulz/controller/TransactionController.kt

@@ -0,0 +1,73 @@
+package ltd.lulz.controller
+
+import io.github.oshai.kotlinlogging.KotlinLogging
+import jakarta.validation.Valid
+import ltd.lulz.exception.AccountNotFoundException
+import ltd.lulz.exception.InsufficientFundsException
+import ltd.lulz.model.Transaction
+import ltd.lulz.model.Transfer
+import ltd.lulz.service.TransactionService
+import org.springframework.http.HttpStatus.CREATED
+import org.springframework.http.HttpStatus.INTERNAL_SERVER_ERROR
+import org.springframework.http.HttpStatus.NOT_ACCEPTABLE
+import org.springframework.http.HttpStatus.NOT_FOUND
+import org.springframework.validation.annotation.Validated
+import org.springframework.web.bind.annotation.PostMapping
+import org.springframework.web.bind.annotation.RequestBody
+import org.springframework.web.bind.annotation.ResponseStatus
+import org.springframework.web.bind.annotation.RestController
+import org.springframework.web.server.ResponseStatusException
+import reactor.core.publisher.Mono
+
+private val log = KotlinLogging.logger {}
+
+@Validated
+@RestController
+class TransactionController(
+    private val transactionService: TransactionService,
+) {
+
+    @PostMapping("/deposit")
+    @ResponseStatus(CREATED)
+    fun deposit(
+        @Valid @RequestBody request: Transaction.Request,
+    ): Mono<Void> = transactionService.deposit(request.account, request.amount)
+        .onErrorResume {
+            when (it) {
+                is AccountNotFoundException -> Mono.error(ResponseStatusException(NOT_FOUND))
+                else -> Mono.error(ResponseStatusException(INTERNAL_SERVER_ERROR))
+            }
+        }
+        .doOnError { log.warn { "deposit account ${request.account}: " + it.localizedMessage } }
+        .then()
+
+    @PostMapping("/withdrawal")
+    @ResponseStatus(CREATED)
+    fun withdrawal(
+        @Valid @RequestBody request: Transaction.Request,
+    ): Mono<Void> = transactionService.withdrawal(request.account, request.amount)
+        .onErrorResume {
+            when (it) {
+                is InsufficientFundsException -> Mono.error(ResponseStatusException(NOT_ACCEPTABLE))
+                is AccountNotFoundException -> Mono.error(ResponseStatusException(NOT_FOUND))
+                else -> Mono.error(ResponseStatusException(INTERNAL_SERVER_ERROR))
+            }
+        }
+        .doOnError { log.warn { "withdrawal account ${request.account}: " + it.localizedMessage } }
+        .then()
+
+    @PostMapping("/transfer")
+    @ResponseStatus(CREATED)
+    fun transfer(
+        @Valid @RequestBody request: Transfer.Request,
+    ): Mono<Void> = transactionService.transfer(request.account, request.receiver, request.amount)
+        .onErrorResume {
+            when (it) {
+                is InsufficientFundsException -> Mono.error(ResponseStatusException(NOT_ACCEPTABLE))
+                is AccountNotFoundException -> Mono.error(ResponseStatusException(NOT_FOUND))
+                else -> Mono.error(ResponseStatusException(INTERNAL_SERVER_ERROR))
+            }
+        }
+        .doOnError { log.warn { "transfer account ${request.account}: " + it.localizedMessage } }
+        .then()
+}

src/main/kotlin/ltd/lulz/exception/InsufficientFundsException.kt

@@ -0,0 +1,10 @@
+package ltd.lulz.exception
+
+@Suppress("unused")
+class InsufficientFundsException : RuntimeException {
+
+    constructor() : super()
+    constructor(message: String?) : super(message)
+    constructor(message: String?, cause: Throwable?) : super(message, cause)
+    constructor(cause: Throwable?) : super(cause)
+}

src/main/kotlin/ltd/lulz/model/Transaction.kt

@@ -0,0 +1,14 @@
+package ltd.lulz.model
+
+import jakarta.validation.constraints.DecimalMin
+import java.math.BigDecimal
+import java.util.UUID
+
+object Transaction {
+
+    data class Request(
+        val account: UUID,
+        @field:DecimalMin(value = "0.01")
+        val amount: BigDecimal,
+    )
+}

src/main/kotlin/ltd/lulz/model/Transfer.kt

@@ -0,0 +1,17 @@
+package ltd.lulz.model
+
+import jakarta.validation.constraints.DecimalMin
+import java.math.BigDecimal
+import java.util.UUID
+import ltd.lulz.annotation.SenderReceiver
+
+object Transfer {
+
+    @SenderReceiver
+    data class Request(
+        val account: UUID,
+        val receiver: UUID,
+        @field:DecimalMin(value = "0.01")
+        val amount: BigDecimal,
+    )
+}

src/main/kotlin/ltd/lulz/service/TransactionService.kt

@@ -2,7 +2,9 @@ package ltd.lulz.service
 
 import io.github.oshai.kotlinlogging.KotlinLogging
 import java.math.BigDecimal
+import java.math.BigDecimal.ZERO
 import java.util.UUID
+import ltd.lulz.exception.InsufficientFundsException
 import ltd.lulz.model.AccountEntity
 import org.springframework.stereotype.Service
 import org.springframework.transaction.annotation.Transactional
@@ -23,4 +25,24 @@ class TransactionService(
         .map { it.copy(amount = it.amount + amount) }
         .doOnNext { log.trace { "Deposited $amount to account ${it.id}" } }
         .flatMap { accountService.save(it) }
+
+    @Transactional
+    fun withdrawal(
+        account: UUID,
+        amount: BigDecimal,
+    ): Mono<AccountEntity> = accountService.getForUpdateById(account)
+        .map { it.copy(amount = it.amount - amount) }
+        .filter { it.amount >= ZERO }
+        .doOnNext { log.trace { "withdrawal $amount to account ${it.id}" } }
+        .switchIfEmpty(Mono.error(InsufficientFundsException()))
+        .flatMap { accountService.save(it) }
+
+    @Transactional
+    fun transfer(
+        account: UUID,
+        receiver: UUID,
+        amount: BigDecimal,
+    ): Mono<Void> = withdrawal(account, amount)
+        .zipWith(deposit(receiver, amount))
+        .then()
 }

src/test-integration/kotlin/ltd/lulz/AccountEndpoints.kt

@@ -0,0 +1,113 @@
+package ltd.lulz
+
+import java.math.BigDecimal
+import java.util.UUID
+import ltd.lulz.model.Account
+import ltd.lulz.test.container.PostgresTestContainer
+import org.assertj.core.api.SoftAssertions
+import org.assertj.core.api.junit.jupiter.InjectSoftAssertions
+import org.assertj.core.api.junit.jupiter.SoftAssertionsExtension
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.extension.ExtendWith
+import org.springframework.boot.test.context.SpringBootTest
+import org.springframework.boot.test.context.SpringBootTest.WebEnvironment.RANDOM_PORT
+import org.springframework.boot.test.web.server.LocalServerPort
+import org.springframework.http.HttpStatus.BAD_REQUEST
+import org.springframework.http.HttpStatus.CREATED
+import org.springframework.http.HttpStatus.NOT_FOUND
+import org.springframework.http.HttpStatus.OK
+import org.springframework.test.web.reactive.server.WebTestClient
+import org.springframework.test.web.reactive.server.expectBody
+
+@PostgresTestContainer
+@SpringBootTest(webEnvironment = RANDOM_PORT)
+@ExtendWith(SoftAssertionsExtension::class)
+class AccountEndpoints {
+
+    @InjectSoftAssertions
+    lateinit var softly: SoftAssertions
+
+    @LocalServerPort
+    var port: Int = 0
+
+    lateinit var webClient: WebTestClient
+
+    @BeforeEach
+    fun setup() {
+        webClient = WebTestClient.bindToServer().baseUrl("http://localhost:$port").build()
+    }
+
+    @Test
+    fun `create account - success add account to db`() {
+        // given
+        val request = Account.Request(
+            name = "user",
+            amount = BigDecimal.valueOf(10.01),
+        )
+
+        // when
+        val result = webClient.post()
+            .uri("/account")
+            .bodyValue(request)
+            .exchange()
+
+        // then
+        result.expectStatus().isEqualTo(CREATED)
+            .expectBody<Account.Response>()
+            .consumeWith {
+                softly.assertThat(it.responseBody?.id?.version()).isEqualTo(7)
+                softly.assertThat(it.responseBody?.name).isEqualTo("user")
+                softly.assertThat(it.responseBody?.amount).isEqualTo("10.01")
+            }
+    }
+
+    @Test
+    fun `create account - fail amount to small`() {
+        // given
+        val request = Account.Request(
+            name = "user",
+            amount = BigDecimal.valueOf(0.009),
+        )
+
+        // when
+        val result = webClient.post()
+            .uri("/account")
+            .bodyValue(request)
+            .exchange()
+
+        // then
+        result.expectStatus().isEqualTo(BAD_REQUEST)
+    }
+
+    @Test
+    fun `get balance - success get balance from db`() {
+        // given
+        val user1 = UUID.fromString("00000000-0000-7000-0000-000000000001")
+
+        // when
+        val result = webClient.get()
+            .uri("/balance/account-$user1")
+            .exchange()
+
+        // then
+        result.expectStatus().isEqualTo(OK)
+            .expectBody<Account.Response>()
+            .consumeWith {
+                softly.assertThat(it.responseBody?.id).isEqualTo(user1)
+                softly.assertThat(it.responseBody?.name).isEqualTo("user 1")
+                softly.assertThat(it.responseBody?.amount).isEqualTo("10.00")
+            }
+    }
+
+    @Test
+    fun `get balance - fail account not found`() {
+        // when
+        val result = webClient.get()
+            .uri("/balance/account-00000000-0000-7000-0000-000000000000")
+            .exchange()
+
+        // then
+        result.expectStatus().isEqualTo(NOT_FOUND)
+    }
+}

src/test-integration/kotlin/ltd/lulz/TransactionEndpoints.kt

@@ -0,0 +1,293 @@
+package ltd.lulz
+
+import java.math.BigDecimal
+import java.util.UUID
+import ltd.lulz.model.Transaction
+import ltd.lulz.model.Transfer
+import ltd.lulz.test.container.PostgresTestContainer
+import org.assertj.core.api.SoftAssertions
+import org.assertj.core.api.junit.jupiter.InjectSoftAssertions
+import org.assertj.core.api.junit.jupiter.SoftAssertionsExtension
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Nested
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.extension.ExtendWith
+import org.springframework.boot.test.context.SpringBootTest
+import org.springframework.boot.test.context.SpringBootTest.WebEnvironment.RANDOM_PORT
+import org.springframework.boot.test.web.server.LocalServerPort
+import org.springframework.http.HttpStatus.BAD_REQUEST
+import org.springframework.http.HttpStatus.CREATED
+import org.springframework.http.HttpStatus.NOT_ACCEPTABLE
+import org.springframework.http.HttpStatus.NOT_FOUND
+import org.springframework.test.web.reactive.server.WebTestClient
+
+@PostgresTestContainer
+@SpringBootTest(webEnvironment = RANDOM_PORT)
+@ExtendWith(SoftAssertionsExtension::class)
+class TransactionEndpoints {
+
+    @InjectSoftAssertions
+    lateinit var softly: SoftAssertions
+
+    @LocalServerPort
+    var port: Int = 0
+
+    lateinit var webClient: WebTestClient
+
+    @BeforeEach
+    fun setup() {
+        webClient = WebTestClient.bindToServer().baseUrl("http://localhost:$port").build()
+    }
+
+    @Nested
+    inner class DepositTest {
+
+        @Test
+        fun `deposit - success`() {
+            // given
+            val request = Transaction.Request(
+                account = UUID.fromString("00000000-0000-7000-0000-000000000001"),
+                amount = BigDecimal.valueOf(1.00),
+            )
+
+            // when
+            val result = webClient.post()
+                .uri("/deposit")
+                .bodyValue(request)
+                .exchange()
+
+            // then
+            result.expectStatus().isEqualTo(CREATED)
+        }
+
+        @Test
+        fun `deposit - fail amount to small`() {
+            // given
+            val request = Transaction.Request(
+                account = UUID.fromString("00000000-0000-7000-0000-000000000001"),
+                amount = BigDecimal.valueOf(0.009),
+            )
+
+            // when
+            val result = webClient.post()
+                .uri("/deposit")
+                .bodyValue(request)
+                .exchange()
+
+            // then
+            result.expectStatus().isEqualTo(BAD_REQUEST)
+        }
+
+        @Test
+        fun `deposit - fail account not found`() {
+            // given
+            val request = Transaction.Request(
+                account = UUID.fromString("00000000-0000-7000-0000-000000000000"),
+                amount = BigDecimal.valueOf(0.01),
+            )
+
+            // when
+            val result = webClient.post()
+                .uri("/deposit")
+                .bodyValue(request)
+                .exchange()
+
+            // then
+            result.expectStatus().isEqualTo(NOT_FOUND)
+        }
+    }
+
+    @Nested
+    inner class WithdrawalTest {
+
+        @Test
+        fun `deposit - success`() {
+            // given
+            val request = Transaction.Request(
+                account = UUID.fromString("00000000-0000-7000-0000-000000000001"),
+                amount = BigDecimal.valueOf(1.00),
+            )
+
+            // when
+            val result = webClient.post()
+                .uri("/withdrawal")
+                .bodyValue(request)
+                .exchange()
+
+            // then
+            result.expectStatus().isEqualTo(CREATED)
+        }
+
+        @Test
+        fun `deposit - fail amount to small`() {
+            // given
+            val request = Transaction.Request(
+                account = UUID.fromString("00000000-0000-7000-0000-000000000001"),
+                amount = BigDecimal.valueOf(0.009),
+            )
+
+            // when
+            val result = webClient.post()
+                .uri("/withdrawal")
+                .bodyValue(request)
+                .exchange()
+
+            // then
+            result.expectStatus().isEqualTo(BAD_REQUEST)
+        }
+
+        @Test
+        fun `deposit - fail account not found`() {
+            // given
+            val request = Transaction.Request(
+                account = UUID.fromString("00000000-0000-7000-0000-000000000000"),
+                amount = BigDecimal.valueOf(1.00),
+            )
+
+            // when
+            val result = webClient.post()
+                .uri("/withdrawal")
+                .bodyValue(request)
+                .exchange()
+
+            // then
+            result.expectStatus().isEqualTo(NOT_FOUND)
+        }
+
+        @Test
+        fun `deposit - fail insufficient funds`() {
+            // given
+            val request = Transaction.Request(
+                account = UUID.fromString("00000000-0000-7000-0000-000000000001"),
+                amount = BigDecimal.valueOf(100.00),
+            )
+
+            // when
+            val result = webClient.post()
+                .uri("/withdrawal")
+                .bodyValue(request)
+                .exchange()
+
+            // then
+            result.expectStatus().isEqualTo(NOT_ACCEPTABLE)
+        }
+    }
+
+    @Nested
+    inner class TransferTest {
+
+        @Test
+        fun `deposit - success`() {
+            // given
+            val request = Transfer.Request(
+                account = UUID.fromString("00000000-0000-7000-0000-000000000001"),
+                receiver = UUID.fromString("00000000-0000-7000-0000-000000000002"),
+                amount = BigDecimal.valueOf(1.00),
+            )
+
+            // when
+            val result = webClient.post()
+                .uri("/transfer")
+                .bodyValue(request)
+                .exchange()
+
+            // then
+            result.expectStatus().isEqualTo(CREATED)
+        }
+
+        @Test
+        fun `deposit - fail same account`() {
+            // given
+            val request = Transfer.Request(
+                account = UUID.fromString("00000000-0000-7000-0000-000000000001"),
+                receiver = UUID.fromString("00000000-0000-7000-0000-000000000001"),
+                amount = BigDecimal.valueOf(1.00),
+            )
+
+            // when
+            val result = webClient.post()
+                .uri("/transfer")
+                .bodyValue(request)
+                .exchange()
+
+            // then
+            result.expectStatus().isEqualTo(BAD_REQUEST)
+        }
+
+        @Test
+        fun `deposit - fail amount to small`() {
+            // given
+            val request = Transfer.Request(
+                account = UUID.fromString("00000000-0000-7000-0000-000000000001"),
+                receiver = UUID.fromString("00000000-0000-7000-0000-000000000002"),
+                amount = BigDecimal.valueOf(0.009),
+            )
+
+            // when
+            val result = webClient.post()
+                .uri("/transfer")
+                .bodyValue(request)
+                .exchange()
+
+            // then
+            result.expectStatus().isEqualTo(BAD_REQUEST)
+        }
+
+        @Test
+        fun `deposit - fail account not found`() {
+            // given
+            val request = Transfer.Request(
+                account = UUID.fromString("00000000-0000-7000-0000-000000000000"),
+                receiver = UUID.fromString("00000000-0000-7000-0000-000000000002"),
+                amount = BigDecimal.valueOf(1.00),
+            )
+
+            // when
+            val result = webClient.post()
+                .uri("/transfer")
+                .bodyValue(request)
+                .exchange()
+
+            // then
+            result.expectStatus().isEqualTo(NOT_FOUND)
+        }
+
+        @Test
+        fun `deposit - fail receiver not found`() {
+            // given
+            val request = Transfer.Request(
+                account = UUID.fromString("00000000-0000-7000-0000-000000000001"),
+                receiver = UUID.fromString("00000000-0000-7000-0000-000000000000"),
+                amount = BigDecimal.valueOf(1.00),
+            )
+
+            // when
+            val result = webClient.post()
+                .uri("/transfer")
+                .bodyValue(request)
+                .exchange()
+
+            // then
+            result.expectStatus().isEqualTo(NOT_FOUND)
+        }
+
+        @Test
+        fun `deposit - fail insufficient funds`() {
+            // given
+            val request = Transfer.Request(
+                account = UUID.fromString("00000000-0000-7000-0000-000000000001"),
+                receiver = UUID.fromString("00000000-0000-7000-0000-000000000002"),
+                amount = BigDecimal.valueOf(100.00),
+            )
+
+            // when
+            val result = webClient.post()
+                .uri("/transfer")
+                .bodyValue(request)
+                .exchange()
+
+            // then
+            result.expectStatus().isEqualTo(NOT_ACCEPTABLE)
+        }
+    }
+}

src/test-integration/resources/postgres/data.sql

@@ -0,0 +1,3 @@
+INSERT INTO public.accounts(id, name, amount)
+VALUES ('00000000-0000-7000-0000-000000000001'::uuid, 'user 1', 10.0),
+       ('00000000-0000-7000-0000-000000000002'::uuid, 'user 2', 10.0);

src/test-integration/resources/postgres/reset.sql

@@ -0,0 +1 @@
+TRUNCATE TABLE accounts CASCADE;

src/test-integration/resources/postgres/schema.sql

@@ -0,0 +1,7 @@
+CREATE TABLE IF NOT EXISTS public.accounts
+(
+    id   UUID DEFAULT uuidv7(),
+    name VARCHAR(50) NOT NULL,
+    amount  NUMERIC(19, 2) NOT NULL,
+    CONSTRAINT pk_contact_types PRIMARY KEY (id)
+);

src/test/kotlin/ltd/lulz/controller/TransactionControllerTest.kt

@@ -0,0 +1,305 @@
+package ltd.lulz.controller
+
+import io.mockk.every
+import io.mockk.mockk
+import java.math.BigDecimal
+import java.util.UUID
+import ltd.lulz.controller.AccountControllerTest.Companion.name
+import ltd.lulz.exception.AccountNotFoundException
+import ltd.lulz.exception.InsufficientFundsException
+import ltd.lulz.model.AccountEntity
+import ltd.lulz.model.Transaction
+import ltd.lulz.model.Transfer
+import ltd.lulz.service.TransactionService
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Test
+import org.springframework.http.HttpStatus.NOT_ACCEPTABLE
+import org.springframework.http.MediaType.APPLICATION_JSON
+import org.springframework.test.web.reactive.server.WebTestClient
+import reactor.core.publisher.Mono
+
+@Suppress("ReactiveStreamsUnusedPublisher")
+class TransactionControllerTest {
+
+    companion object {
+        val amount: BigDecimal = BigDecimal.valueOf(0.01)
+        val uuid: UUID = UUID.fromString("00000000-0000-0000-0000-000000000000")
+        val receiver = UUID.fromString("00000000-0000-0000-0000-000000000001")
+    }
+
+    private val transactionService: TransactionService = mockk()
+    private lateinit var webTestClient: WebTestClient
+
+    @BeforeEach
+    fun setUp() {
+        webTestClient = WebTestClient.bindToController(TransactionController(transactionService)).build()
+    }
+
+    @Test
+    fun `deposit success`() {
+        // given
+        val request = Transaction.Request(uuid, amount)
+
+        every { transactionService.deposit(any(), any()) } returns Mono.just(
+            AccountEntity(id = uuid, name = name, amount = amount),
+        )
+
+        // when
+        val result = webTestClient.post()
+            .uri("/deposit")
+            .contentType(APPLICATION_JSON)
+            .bodyValue(request)
+            .exchange()
+
+        // then
+        result.expectStatus().isCreated
+    }
+
+    @Test
+    fun `deposit fail amount to small`() {
+        // given
+        val request = Transaction.Request(uuid, BigDecimal.valueOf(0.009))
+
+        // when
+        val result = webTestClient.post()
+            .uri("/deposit")
+            .contentType(APPLICATION_JSON)
+            .bodyValue(request)
+            .exchange()
+
+        // then
+        result.expectStatus().isBadRequest
+    }
+
+    @Test
+    fun `deposit default error`() {
+        // given
+        val request = Transaction.Request(uuid, amount)
+
+        every { transactionService.deposit(any(), any()) } returns Mono.error(RuntimeException())
+
+        // when
+        val result = webTestClient.post()
+            .uri("/deposit")
+            .contentType(APPLICATION_JSON)
+            .bodyValue(request)
+            .exchange()
+
+        // then
+        result.expectStatus().is5xxServerError
+    }
+
+    @Test
+    fun `deposit account not found`() {
+        // given
+        val request = Transaction.Request(uuid, amount)
+
+        every { transactionService.deposit(any(), any()) } returns Mono.error(AccountNotFoundException())
+
+        // when
+        val result = webTestClient.post()
+            .uri("/deposit")
+            .contentType(APPLICATION_JSON)
+            .bodyValue(request)
+            .exchange()
+
+        // then
+        result.expectStatus().isNotFound
+    }
+
+    @Test
+    fun `withdrawal success`() {
+        // given
+        val request = Transaction.Request(uuid, amount)
+
+        every { transactionService.withdrawal(any(), any()) } returns Mono.just(
+            AccountEntity(id = uuid, name = name, amount = amount),
+        )
+
+        // when
+        val result = webTestClient.post()
+            .uri("/withdrawal")
+            .contentType(APPLICATION_JSON)
+            .bodyValue(request)
+            .exchange()
+
+        // then
+        result.expectStatus().isCreated
+    }
+
+    @Test
+    fun `withdrawal fail amount to small`() {
+        // given
+        val request = Transaction.Request(uuid, BigDecimal.valueOf(0.009))
+
+        // when
+        val result = webTestClient.post()
+            .uri("/withdrawal")
+            .contentType(APPLICATION_JSON)
+            .bodyValue(request)
+            .exchange()
+
+        // then
+        result.expectStatus().isBadRequest
+    }
+
+    @Test
+    fun `withdrawal insufficient Funds`() {
+        // given
+        val request = Transaction.Request(uuid, amount)
+
+        every { transactionService.withdrawal(any(), any()) } returns Mono.error(InsufficientFundsException())
+
+        // when
+        val result = webTestClient.post()
+            .uri("/withdrawal")
+            .contentType(APPLICATION_JSON)
+            .bodyValue(request)
+            .exchange()
+
+        // then
+        result.expectStatus().isEqualTo(NOT_ACCEPTABLE)
+    }
+
+    @Test
+    fun `withdrawal account not found`() {
+        // given
+        val request = Transaction.Request(uuid, amount)
+
+        every { transactionService.withdrawal(any(), any()) } returns Mono.error(AccountNotFoundException())
+
+        // when
+        val result = webTestClient.post()
+            .uri("/withdrawal")
+            .contentType(APPLICATION_JSON)
+            .bodyValue(request)
+            .exchange()
+
+        // then
+        result.expectStatus().isNotFound
+    }
+
+    @Test
+    fun `withdrawal default error`() {
+        // given
+        val request = Transaction.Request(uuid, amount)
+
+        every { transactionService.withdrawal(any(), any()) } returns Mono.error(RuntimeException())
+
+        // when
+        val result = webTestClient.post()
+            .uri("/withdrawal")
+            .contentType(APPLICATION_JSON)
+            .bodyValue(request)
+            .exchange()
+
+        // then
+        result.expectStatus().is5xxServerError
+    }
+
+    @Test
+    fun `transfer success`() {
+        // given
+        val request = Transfer.Request(uuid, receiver, amount)
+
+        every { transactionService.transfer(any(), any(), any()) } returns Mono.empty()
+
+        // when
+        val result = webTestClient.post()
+            .uri("/transfer")
+            .contentType(APPLICATION_JSON)
+            .bodyValue(request)
+            .exchange()
+
+        // then
+        result.expectStatus().isCreated
+    }
+
+    @Test
+    fun `transfer fail same accounts`() {
+        // given
+        val request = Transfer.Request(uuid, uuid, amount)
+
+        every { transactionService.transfer(any(), any(), any()) } returns Mono.empty()
+
+        // when
+        val result = webTestClient.post()
+            .uri("/transfer")
+            .contentType(APPLICATION_JSON)
+            .bodyValue(request)
+            .exchange()
+
+        // then
+        result.expectStatus().isBadRequest
+    }
+
+    @Test
+    fun `transfer fail amount to small`() {
+        // given
+        val request = Transfer.Request(uuid, receiver, BigDecimal.valueOf(0.009))
+
+        // when
+        val result = webTestClient.post()
+            .uri("/transfer")
+            .contentType(APPLICATION_JSON)
+            .bodyValue(request)
+            .exchange()
+
+        // then
+        result.expectStatus().isBadRequest
+    }
+
+    @Test
+    fun `transfer insufficient Funds`() {
+        // given
+        val request = Transfer.Request(uuid, receiver, amount)
+
+        every { transactionService.transfer(any(), any(), any()) } returns Mono.error(InsufficientFundsException())
+
+        // when
+        val result = webTestClient.post()
+            .uri("/transfer")
+            .contentType(APPLICATION_JSON)
+            .bodyValue(request)
+            .exchange()
+
+        // then
+        result.expectStatus().isEqualTo(NOT_ACCEPTABLE)
+    }
+
+    @Test
+    fun `transfer account not found`() {
+        // given
+        val request = Transfer.Request(uuid, receiver, amount)
+
+        every { transactionService.transfer(any(), any(), any()) } returns Mono.error(AccountNotFoundException())
+
+        // when
+        val result = webTestClient.post()
+            .uri("/transfer")
+            .contentType(APPLICATION_JSON)
+            .bodyValue(request)
+            .exchange()
+
+        // then
+        result.expectStatus().isNotFound
+    }
+
+    @Test
+    fun `transfer default error`() {
+        // given
+        val request = Transfer.Request(uuid, receiver, amount)
+
+        every { transactionService.transfer(any(), any(), any()) } returns Mono.error(RuntimeException())
+
+        // when
+        val result = webTestClient.post()
+            .uri("/transfer")
+            .contentType(APPLICATION_JSON)
+            .bodyValue(request)
+            .exchange()
+
+        // then
+        result.expectStatus().is5xxServerError
+    }
+}

src/test/kotlin/ltd/lulz/service/TransactionServiceTest.kt

@@ -7,9 +7,11 @@ import io.mockk.verify
 import java.math.BigDecimal
 import java.util.UUID
 import ltd.lulz.exception.AccountNotFoundException
+import ltd.lulz.exception.InsufficientFundsException
 import ltd.lulz.model.AccountEntity
 import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Nested
 import org.junit.jupiter.api.Test
 import reactor.core.publisher.Mono
 import reactor.test.StepVerifier
@@ -18,9 +20,12 @@ import reactor.test.StepVerifier
 class TransactionServiceTest {
 
     companion object {
-        val name: String = "some name"
+        val accountName: String = "some name"
-        val amount: BigDecimal = BigDecimal.valueOf(1.01)
+        val accountAmount: BigDecimal = BigDecimal.valueOf(1.01)
-        val uuid: UUID = UUID.fromString("00000000-0000-0000-0000-000000000000")
+        val accountUuid: UUID = UUID.fromString("00000000-0000-0000-0000-000000000000")
+        val receiverName: String = "different name"
+        val receiverAmount: BigDecimal = BigDecimal.valueOf(1.01)
+        val receiverUuid: UUID = UUID.fromString("00000000-0000-0000-0000-000000000001")
     }
 
     private val accountService: AccountService = mockk()
@@ -31,6 +36,9 @@ class TransactionServiceTest {
         service = TransactionService(accountService)
     }
 
+    @Nested
+    inner class Deposit {
+
         @Test
         fun `deposit to account - success`() {
             // given
@@ -38,17 +46,17 @@ class TransactionServiceTest {
 
             val capture = slot<UUID>()
             every { accountService.getForUpdateById(capture(capture)) }
-            .answers { Mono.just(AccountEntity(capture.captured, name, amount)) }
+                .answers { Mono.just(AccountEntity(capture.captured, accountName, accountAmount)) }
             val entity = slot<AccountEntity>()
             every { accountService.save(capture(entity)) }
                 .answers { Mono.just(entity.captured) }
 
             // when stepped
-        StepVerifier.create(service.deposit(uuid, deposit))
+            StepVerifier.create(service.deposit(accountUuid, deposit))
                 .assertNext { result ->
-                assertThat(result.id).isEqualTo(uuid)
+                    assertThat(result.id).isEqualTo(accountUuid)
-                assertThat(result.name).isEqualTo(name)
+                    assertThat(result.name).isEqualTo(accountName)
-                assertThat(result.amount).isEqualTo(amount + deposit)
+                    assertThat(result.amount).isEqualTo(accountAmount + deposit)
                 }
                 .verifyComplete()
 
@@ -64,7 +72,7 @@ class TransactionServiceTest {
             every { accountService.getForUpdateById(any()) } returns Mono.error(AccountNotFoundException())
 
             // when stepped
-        StepVerifier.create(service.deposit(uuid, deposit))
+            StepVerifier.create(service.deposit(accountUuid, deposit))
                 .expectError(AccountNotFoundException::class.java)
                 .verify()
 
@@ -72,3 +80,158 @@ class TransactionServiceTest {
             verify(exactly = 0) { accountService.save(any()) }
         }
     }
+
+    @Nested
+    inner class Withdrawal {
+
+        @Test
+        fun `withdrawal from account - success`() {
+            // given
+            val deposit = BigDecimal.valueOf(1.01)
+
+            val capture = slot<UUID>()
+            every { accountService.getForUpdateById(capture(capture)) }
+                .answers { Mono.just(AccountEntity(capture.captured, accountName, accountAmount)) }
+            val entity = slot<AccountEntity>()
+            every { accountService.save(capture(entity)) }
+                .answers { Mono.just(entity.captured) }
+
+            // when stepped
+            StepVerifier.create(service.withdrawal(accountUuid, deposit))
+                .assertNext { result ->
+                    assertThat(result.id).isEqualTo(accountUuid)
+                    assertThat(result.name).isEqualTo(accountName)
+                    assertThat(result.amount).isEqualTo(accountAmount - deposit)
+                }
+                .verifyComplete()
+
+            verify(exactly = 1) { accountService.getForUpdateById(any(UUID::class)) }
+            verify(exactly = 1) { accountService.save(any()) }
+        }
+
+        @Test
+        fun `withdrawal from account - insufficient founds`() {
+            // given
+            val deposit = BigDecimal.valueOf(1.10)
+
+            val capture = slot<UUID>()
+            every { accountService.getForUpdateById(capture(capture)) }
+                .answers { Mono.just(AccountEntity(capture.captured, accountName, accountAmount)) }
+
+            // when stepped
+            StepVerifier.create(service.withdrawal(accountUuid, deposit))
+                .expectError(InsufficientFundsException::class.java)
+                .verify()
+
+            verify(exactly = 1) { accountService.getForUpdateById(any(UUID::class)) }
+            verify(exactly = 0) { accountService.save(any()) }
+        }
+
+        @Test
+        fun `withdrawal from account - account not found`() {
+            // given
+            val deposit = BigDecimal.valueOf(1.10)
+
+            every { accountService.getForUpdateById(any()) } returns Mono.error(AccountNotFoundException())
+
+            // when stepped
+            StepVerifier.create(service.withdrawal(accountUuid, deposit))
+                .expectError(AccountNotFoundException::class.java)
+                .verify()
+
+            verify(exactly = 1) { accountService.getForUpdateById(any(UUID::class)) }
+            verify(exactly = 0) { accountService.save(any()) }
+        }
+    }
+
+    @Nested
+    inner class Transfer {
+
+        @Test
+        fun `transfer from account - success`() {
+            // given
+            val transfer = BigDecimal.valueOf(1.00)
+
+            val capture = slot<UUID>()
+            every { accountService.getForUpdateById(capture(capture)) }
+                .answers { Mono.just(AccountEntity(capture.captured, accountName, accountAmount)) }
+                .andThenAnswer { Mono.just(AccountEntity(capture.captured, receiverName, receiverAmount)) }
+            val entity = slot<AccountEntity>()
+            every { accountService.save(capture(entity)) }
+                .answers { Mono.just(entity.captured) }
+
+            // when stepped
+            StepVerifier.create(service.transfer(accountUuid, receiverUuid, transfer))
+                .verifyComplete()
+
+            verify(exactly = 2) { accountService.getForUpdateById(any(UUID::class)) }
+            verify(exactly = 2) { accountService.save(any()) }
+        }
+
+        @Test
+        fun `transfer from account - insufficient founds`() {
+            // given
+            val transfer = BigDecimal.valueOf(5.00)
+
+            val capture = slot<UUID>()
+            every { accountService.getForUpdateById(capture(capture)) }
+                .answers { Mono.just(AccountEntity(capture.captured, accountName, accountAmount)) }
+                .andThenAnswer { Mono.just(AccountEntity(capture.captured, receiverName, receiverAmount)) }
+            val entity = slot<AccountEntity>()
+            every { accountService.save(capture(entity)) }
+                .answers { Mono.just(entity.captured) }
+
+            // when stepped
+            StepVerifier.create(service.transfer(accountUuid, receiverUuid, transfer))
+                .expectError(InsufficientFundsException::class.java)
+                .verify()
+
+            verify(exactly = 2) { accountService.getForUpdateById(any(UUID::class)) }
+            verify(exactly = 0) { accountService.save(any()) }
+        }
+
+        @Test
+        fun `transfer from account - account not found`() {
+            // given
+            val transfer = BigDecimal.valueOf(1.00)
+
+            val capture = slot<UUID>()
+            every { accountService.getForUpdateById(capture(capture)) }
+                .answers { Mono.error(AccountNotFoundException()) }
+                .andThenAnswer { Mono.just(AccountEntity(capture.captured, receiverName, receiverAmount)) }
+            val entity = slot<AccountEntity>()
+            every { accountService.save(capture(entity)) }
+                .answers { Mono.just(entity.captured) }
+
+            // when stepped
+            StepVerifier.create(service.transfer(accountUuid, receiverUuid, transfer))
+                .expectError(AccountNotFoundException::class.java)
+                .verify()
+
+            verify(exactly = 2) { accountService.getForUpdateById(any(UUID::class)) }
+            verify(exactly = 0) { accountService.save(any()) }
+        }
+
+        @Test
+        fun `transfer from account - receiver not found`() {
+            // given
+            val transfer = BigDecimal.valueOf(1.00)
+
+            val capture = slot<UUID>()
+            every { accountService.getForUpdateById(capture(capture)) }
+                .answers { Mono.just(AccountEntity(capture.captured, accountName, accountAmount)) }
+                .andThenAnswer { Mono.error(AccountNotFoundException()) }
+            val entity = slot<AccountEntity>()
+            every { accountService.save(capture(entity)) }
+                .answers { Mono.just(entity.captured) }
+
+            // when stepped
+            StepVerifier.create(service.transfer(accountUuid, receiverUuid, transfer))
+                .expectError(AccountNotFoundException::class.java)
+                .verify()
+
+            verify(exactly = 2) { accountService.getForUpdateById(any(UUID::class)) }
+            verify(exactly = 1) { accountService.save(any()) }
+        }
+    }
+}