From 4f95265872599b3c5967e4ce0c12c514cafbf585 Mon Sep 17 00:00:00 2001
From: Swordsteel <swordsteel@gmail.com>
Date: Sat, 13 Sep 2025 19:56:25 +0200
Subject: [PATCH] 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
---
 .../ltd/lulz/annotation/SenderReceiver.kt     | 15 +++++++++++++++
 .../validator/SenderReceiverValidator.kt      | 14 ++++++++++++++
 src/main/kotlin/ltd/lulz/model/Transfer.kt    |  2 ++
 .../kotlin/ltd/lulz/TransactionEndpoints.kt   | 19 +++++++++++++++++++
 .../controller/TransactionControllerTest.kt   | 18 ++++++++++++++++++
 5 files changed, 68 insertions(+)
 create mode 100644 src/main/kotlin/ltd/lulz/annotation/SenderReceiver.kt
 create mode 100644 src/main/kotlin/ltd/lulz/annotation/validator/SenderReceiverValidator.kt

diff --git a/src/main/kotlin/ltd/lulz/annotation/SenderReceiver.kt b/src/main/kotlin/ltd/lulz/annotation/SenderReceiver.kt
new file mode 100644
index 0000000..d608370
--- /dev/null
+++ b/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>> = [],
+)
diff --git a/src/main/kotlin/ltd/lulz/annotation/validator/SenderReceiverValidator.kt b/src/main/kotlin/ltd/lulz/annotation/validator/SenderReceiverValidator.kt
new file mode 100644
index 0000000..273f06f
--- /dev/null
+++ b/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
+}
diff --git a/src/main/kotlin/ltd/lulz/model/Transfer.kt b/src/main/kotlin/ltd/lulz/model/Transfer.kt
index 26b206b..2d6a73f 100644
--- a/src/main/kotlin/ltd/lulz/model/Transfer.kt
+++ b/src/main/kotlin/ltd/lulz/model/Transfer.kt
@@ -3,9 +3,11 @@ 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,
diff --git a/src/test-integration/kotlin/ltd/lulz/TransactionEndpoints.kt b/src/test-integration/kotlin/ltd/lulz/TransactionEndpoints.kt
index e60dc55..0c6a9bb 100644
--- a/src/test-integration/kotlin/ltd/lulz/TransactionEndpoints.kt
+++ b/src/test-integration/kotlin/ltd/lulz/TransactionEndpoints.kt
@@ -195,6 +195,25 @@ class TransactionEndpoints {
             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
diff --git a/src/test/kotlin/ltd/lulz/controller/TransactionControllerTest.kt b/src/test/kotlin/ltd/lulz/controller/TransactionControllerTest.kt
index b2762cd..44f0df9 100644
--- a/src/test/kotlin/ltd/lulz/controller/TransactionControllerTest.kt
+++ b/src/test/kotlin/ltd/lulz/controller/TransactionControllerTest.kt
@@ -215,6 +215,24 @@ class TransactionControllerTest {
         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