test: ReadProblemUseCase 단위 테스트 추가

api/src/test/kotlin/com/few/api/domain/problem/usecase/ReadProblemUseCaseTest.kt

@@ -0,0 +1,62 @@
+package com.few.api.domain.problem.usecase
+
+import com.few.api.domain.problem.usecase.dto.ReadProblemUseCaseIn
+import com.few.api.repo.dao.problem.ProblemDao
+import com.few.api.repo.dao.problem.record.SelectProblemRecord
+import com.few.api.repo.dao.problem.support.Content
+import com.few.api.repo.dao.problem.support.Contents
+import com.few.api.repo.dao.problem.support.ContentsJsonMapper
+import io.mockk.every
+import io.mockk.junit5.MockKExtension
+import io.mockk.mockk
+import io.mockk.verify
+import org.junit.jupiter.api.Assertions
+import org.junit.jupiter.api.Test
+
+import org.junit.jupiter.api.extension.ExtendWith
+
+@ExtendWith(MockKExtension::class)
+class ReadProblemUseCaseTest {
+
+    val problemDao: ProblemDao = mockk<ProblemDao>()
+
+    val contentsJsonMapper: ContentsJsonMapper = mockk<ContentsJsonMapper>()
+
+    val useCase = ReadProblemUseCase(problemDao, contentsJsonMapper)
+
+    @Test
+    fun `문제ID로 문제를 조회힌다`() {
+        // given
+        val useCaseIn = ReadProblemUseCaseIn(problemId = 1L)
+        val problemRecord = SelectProblemRecord(id = 1L, title = "title", contents = "{}")
+        val contents = Contents(
+            listOf(
+                Content(number = 1, content = "{}"),
+                Content(number = 2, content = "{}")
+            )
+        )
+
+        every { problemDao.selectProblemContents(any()) } returns problemRecord
+        every { contentsJsonMapper.toObject(any()) } returns contents
+
+        // when
+        useCase.execute(useCaseIn)
+
+        // then
+        verify(exactly = 1) { problemDao.selectProblemContents(any()) }
+        verify(exactly = 1) { contentsJsonMapper.toObject(any()) }
+    }
+
+    @Test
+    fun `문제가 존재하지 않을 경우 예외가 발생한다`() {
+        // given
+        val useCaseIn = ReadProblemUseCaseIn(problemId = 1L)
+
+        every { problemDao.selectProblemContents(any()) } returns null
+
+        // when, then
+        Assertions.assertThrows(Exception::class.java) { useCase.execute(useCaseIn) }
+
+        verify(exactly = 1) { problemDao.selectProblemContents(any()) }
+    }
+}