add request validation

src/test/kotlin/com/example/demo/controllers/ProductControllerTest.kt

@@ -3,16 +3,22 @@ package com.example.demo.controllers
 import com.example.demo.models.Product
 import com.example.demo.responses.ResponseStatus
 import com.example.demo.services.ProductService
+import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
+import org.hamcrest.Matchers.contains
 import org.hamcrest.Matchers.nullValue
 import org.junit.jupiter.api.Test
 import org.mockito.kotlin.doReturn
 import org.mockito.kotlin.eq
+import org.mockito.kotlin.verifyNoInteractions
 import org.mockito.kotlin.whenever
 import org.springframework.beans.factory.annotation.Autowired
 import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest
 import org.springframework.boot.test.mock.mockito.MockBean
+import org.springframework.http.MediaType
 import org.springframework.test.web.servlet.MockMvc
 import org.springframework.test.web.servlet.get
+import org.springframework.test.web.servlet.post
+import org.springframework.web.bind.MethodArgumentNotValidException
 import java.time.OffsetDateTime
 import java.time.format.DateTimeFormatter
 import java.util.*
@@ -21,6 +27,8 @@ import java.util.*
 class ProductControllerTest(@Autowired val mockMvc: MockMvc) {
     @MockBean
     private lateinit var productService: ProductService
+    private val mapper = jacksonObjectMapper()
+
 
     @Test
     fun getProduct_success() {
@@ -43,7 +51,7 @@ class ProductControllerTest(@Autowired val mockMvc: MockMvc) {
 
         mockMvc.get("/api/product/$guid")
             .andExpect { status { status { isOk() } } }
-            .andExpect { content { contentType("application/json") } }
+            .andExpect { content { contentType(MediaType.APPLICATION_JSON) } }
             .andExpect { jsonPath("\$.id") { value(product.id.toString()) } }
             .andExpect { jsonPath("\$.guid") { value(guid.toString()) } }
             .andExpect { jsonPath("\$.name") { value("some") } }
@@ -61,7 +69,85 @@ class ProductControllerTest(@Autowired val mockMvc: MockMvc) {
 
         mockMvc.get("/api/product/$guid")
             .andExpect { status { status { isNotFound() } } }
-            .andExpect { content { contentType("application/json") } }
+            .andExpect { content { contentType(MediaType.APPLICATION_JSON) } }
             .andExpect { jsonPath("\$.status") { value(ResponseStatus.NOT_FOUND.status) } }
     }
+
+    @Test
+    fun createProduct_success() {
+        val productId = 13.toLong()
+        val name = "new-product"
+        val description = null
+        val price = 20000.toLong()
+
+        val reqBody = mapper.writeValueAsString(
+            mapOf("name" to name, "description" to description, "price" to price)
+        )
+
+        whenever(productService.create(
+            eq(name),
+            eq(price),
+            eq(description)
+        )) doReturn Product(
+            id = productId,
+            guid = UUID.randomUUID(),
+            name = name,
+            description = description,
+            price = price,
+            createdAt = OffsetDateTime.now(),
+            updatedAt = null,
+            deletedAt = null,
+        )
+
+        mockMvc.post("/api/product") {
+            contentType = MediaType.APPLICATION_JSON
+            content = reqBody
+        }
+            .andExpect { status { status { isCreated() } } }
+            .andExpect { content { contentType(MediaType.APPLICATION_JSON) } }
+            .andExpect { jsonPath("\$.id") { value(productId) } }
+    }
+
+    @Test
+    fun createProduct_badRequest_noNameParam() {
+        val description = null
+        val price = 20000.toLong()
+
+        val reqBody = mapper.writeValueAsString(
+            mapOf("description" to description, "price" to price)
+        )
+
+        verifyNoInteractions(productService)
+
+        mockMvc.post("/api/product") {
+            contentType = MediaType.APPLICATION_JSON
+            content = reqBody
+        }
+            .andExpect { status { status { isBadRequest() } } }
+            .andExpect { content { contentType(MediaType.APPLICATION_JSON) } }
+            .andExpect { jsonPath("\$.status") { value(ResponseStatus.BAD_REQUEST.status) } }
+            .andExpect { jsonPath("\$.cause") { contains("name") } }
+    }
+
+    @Test
+    fun createProduct_badRequest_emptyName() {
+        val description = null
+        val price = 20000.toLong()
+
+        val reqBody = mapper.writeValueAsString(
+            mapOf("name" to "", "description" to description, "price" to price)
+        )
+
+        verifyNoInteractions(productService)
+
+        mockMvc.post("/api/product") {
+            contentType = MediaType.APPLICATION_JSON
+            content = reqBody
+        }
+            .andExpect { status { status { isUnprocessableEntity() } } }
+            .andExpect { content { contentType(MediaType.APPLICATION_JSON) } }
+            .andExpect { jsonPath("\$.status") { value(ResponseStatus.UNPROCESSABLE.status) } }
+            .andExpect { jsonPath("\$.cause") { value(MethodArgumentNotValidException::class.qualifiedName) } }
+
+    }
 }