test: 기존 Junit 테스트와 동일한 Kotest 기반 테스트 추가

README.md

@@ -12,7 +12,10 @@
 git clone https://gitea.pricelees.me/pricelees/kopring-validation.git
 
 // 테스트 실행 후 콘솔 출력 결과 확인
-src.test/kotlin/com/sangdol/validation/ValidationTest.kt
+src/test/kotlin/com/sangdol/validation/DemoControllerTest
+
+// Kotest 버전
+src/test/kotlin/com/sangdol/validation/DemoControllerKTest
 ```
 `src/main/kotlin/com/sangdol/validation/DemoDTO.kt` 를 Decompile 하여 상황에 따라 어노테이션이 어떻게 붙는지 확인할 수 있습니다. 
 - 같은 @NotNull 이라도 jakarta / jetbrains 패키지인지에 따라 처리되는 방법이 다르며, 자세한 내용은 위 글에서 확인할 수 있습니다. 

build.gradle.kts

@@ -31,6 +31,9 @@ dependencies {
     implementation("com.fasterxml.jackson.module:jackson-module-kotlin")
     implementation("io.github.oshai:kotlin-logging-jvm:7.0.3")
 
+    testImplementation("io.mockk:mockk:1.14.4")
+    testImplementation("io.kotest:kotest-runner-junit5:5.9.1")
+    testImplementation("io.kotest.extensions:kotest-extensions-spring:1.3.0")
     testImplementation("org.springframework.boot:spring-boot-starter-test")
     testRuntimeOnly("org.junit.platform:junit-platform-launcher")
 }

src/test/kotlin/com/sangdol/validation/DemoControllerKTest.kt

@@ -0,0 +1,90 @@
+package com.sangdol.validation
+
+import io.kotest.core.annotation.DisplayName
+import io.kotest.core.spec.style.BehaviorSpec
+import org.hamcrest.CoreMatchers.containsString
+import org.springframework.beans.factory.annotation.Autowired
+import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest
+import org.springframework.http.HttpStatus
+import org.springframework.http.MediaType
+import org.springframework.test.context.bean.override.mockito.MockitoBean
+import org.springframework.test.web.servlet.MockMvc
+import org.springframework.test.web.servlet.ResultActions
+import org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post
+import org.springframework.test.web.servlet.result.MockMvcResultHandlers.print
+import org.springframework.test.web.servlet.result.MockMvcResultMatchers.*
+import kotlin.random.Random
+
+@WebMvcTest(controllers = [DemoController::class])
+@DisplayName("타입별 Bean Validation 테스트")
+class DemoControllerKTest(
+    @Autowired private val mockMvc: MockMvc,
+    @MockitoBean private val demoService: DemoService
+) : BehaviorSpec() {
+
+    init {
+        Given("Wrapper 타입에서는") {
+            val endpoint = "/wrapper"
+            val value = "value"
+
+            When("값이 입력되지 않으면") {
+                val expectedStatus = HttpStatus.BAD_REQUEST.value()
+                val expectedError = "HttpMessageNotReadableException"
+
+                Then("HttpMessageNotReadableException이 발생한다.") {
+                    val body = "{\"withAnnotation\": \"$value\"}"
+                    runException(endpoint, body, expectedStatus, expectedError)
+                }
+
+                Then("@NotNull이 적용되지 않고 HttpMessageNotReadableException이 발생한다.") {
+                    val body = "{\"withoutAnnotation\": \"$value\"}"
+                    runException(endpoint, body, expectedStatus, expectedError)
+                }
+            }
+        }
+
+        Given("Primitive 타입에서는") {
+            val endpoint = "/primitive"
+            val value = Random.nextInt()
+
+            When("값을 입력하지 않아도") {
+                val expectedStatus = HttpStatus.OK.value()
+
+                Then("@NotNull과 무관하게 기본값이 들어간다.") {
+                    run(endpoint, "{\"withoutAnnotation\": \"$value\"}", expectedStatus)
+                }
+            }
+        }
+
+        Given("Primitive 타입에서 @NotNull + Nullable 으로 선언한 경우에는") {
+            val endpoint = "/solution"
+
+            When("값이 입력되지 않으면") {
+                val body = "{\"notExistField\": 10}"
+                val expectedStatus = HttpStatus.BAD_REQUEST.value()
+                val expectedError = "MethodArgumentNotValidException"
+
+                Then("@NotNull Bean Validation이 적용된다.") {
+                    runException(endpoint, body, expectedStatus, expectedError)
+                }
+            }
+        }
+    }
+
+    private fun run(endpoint: String, body: String, expectedStatus: Int): ResultActions =
+        mockMvc.perform(
+            post(endpoint)
+                .contentType(MediaType.APPLICATION_JSON_VALUE)
+                .content(body)
+        ).andExpect(status().`is`(expectedStatus))
+            .andDo(print())
+
+    private fun runException(
+        endpoint: String,
+        body: String,
+        expectedStatus: Int,
+        expectedExceptionType: String
+    ): ResultActions =
+        run(endpoint, body, expectedStatus)
+            .andExpect(jsonPath("$.type", containsString(expectedExceptionType)))
+}