test: BrowseProblemsUseCase 단위 테스트 추가

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

@@ -0,0 +1,48 @@
+package com.few.api.domain.problem.usecase
+
+import com.few.api.domain.problem.usecase.dto.BrowseProblemsUseCaseIn
+import com.few.api.repo.dao.problem.ProblemDao
+import com.few.api.repo.dao.problem.record.ProblemIdsRecord
+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 BrowseProblemsUseCaseTest {
+
+    val problemDao: ProblemDao = mockk<ProblemDao>()
+
+    val useCase = BrowseProblemsUseCase(problemDao)
+
+    @Test
+    fun `특정 아티클에 문제가 존재할 경우 문제번호가 정상적으로 조회된다`() {
+        // given
+        val useCaseIn = BrowseProblemsUseCaseIn(articleId = 1L)
+        val problemIdsRecord = ProblemIdsRecord(listOf(1, 2, 3))
+
+        every { problemDao.selectProblemsByArticleId(any()) } returns problemIdsRecord
+
+        // when
+        useCase.execute(useCaseIn)
+
+        // then
+        verify(exactly = 1) { problemDao.selectProblemsByArticleId(any()) }
+    }
+
+    @Test
+    fun `특정 아티클에 문제가 존재하지 않을 경우 예외가 발생한다`() {
+        // given
+        val useCaseIn = BrowseProblemsUseCaseIn(articleId = 1L)
+
+        every { problemDao.selectProblemsByArticleId(any()) } returns null
+
+        // when / then
+        Assertions.assertThrows(Exception::class.java) { useCase.execute(useCaseIn) }
+        verify(exactly = 1) { problemDao.selectProblemsByArticleId(any()) }
+    }
+}