diff --git a/src/test/kotlin/StatsGeneratorApplicationTest.kt b/src/test/kotlin/StatsGeneratorApplicationTest.kt
new file mode 100644
index 0000000..16b3435
--- /dev/null
+++ b/src/test/kotlin/StatsGeneratorApplicationTest.kt
@@ -0,0 +1,94 @@
+
+import dev.hossain.githubstats.AuthorPrStats
+import dev.hossain.githubstats.AuthorStats
+import dev.hossain.githubstats.PrAuthorStatsService
+import dev.hossain.githubstats.PrReviewerStatsService
+import dev.hossain.githubstats.ReviewerReviewStats
+import dev.hossain.githubstats.formatter.StatsFormatter
+import dev.hossain.githubstats.util.AppConfig
+import dev.hossain.i18n.Resources
+import io.mockk.coEvery
+import io.mockk.coVerify
+import io.mockk.mockk
+import io.mockk.verify
+import kotlinx.coroutines.runBlocking
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Test
+import kotlin.time.Duration
+
+/**
+ * Unit test for [StatsGeneratorApplication].
+ */
+class StatsGeneratorApplicationTest {
+
+    private val prReviewerStatsService: PrReviewerStatsService = mockk(relaxed = true)
+    private val prAuthorStatsService: PrAuthorStatsService = mockk(relaxed = true)
+    private val resources: Resources = mockk(relaxed = true)
+    private val appConfig: AppConfig = mockk(relaxed = true)
+    private val formatters: List<StatsFormatter> = listOf(mockk(relaxed = true))
+
+    private lateinit var statsGeneratorApplication: StatsGeneratorApplication
+
+    @BeforeEach
+    fun setUp() {
+        statsGeneratorApplication = StatsGeneratorApplication(
+            prReviewerStatsService,
+            prAuthorStatsService,
+            resources,
+            appConfig,
+            formatters
+        )
+    }
+
+    @Test
+    fun `generateAuthorStats should call authorStats and formatAuthorStats for each user`() = runBlocking {
+        val userIds = listOf("user1", "user2")
+        val authorStats = AuthorStats(
+            AuthorPrStats(
+                authorUserId = "user1",
+                totalPrsCreated = 0,
+                totalIssueComments = 0,
+                totalPrSubmissionComments = 0,
+                totalCodeReviewComments = 0
+            ),
+            emptyList()
+        )
+
+        coEvery { appConfig.get().userIds } returns userIds
+        coEvery { prAuthorStatsService.authorStats(any()) } returns authorStats
+
+        statsGeneratorApplication.generateAuthorStats()
+
+        userIds.forEach { userId ->
+            coVerify { prAuthorStatsService.authorStats(userId) }
+            formatters.forEach { formatter ->
+                verify { formatter.formatAuthorStats(authorStats) }
+            }
+        }
+    }
+
+    @Test
+    fun `generateReviewerStats should call reviewerStats and formatReviewerStats for each user`() = runBlocking {
+        val userIds = listOf("user1", "user2")
+        val reviewerStats = ReviewerReviewStats(
+            repoId = "repo_id",
+            reviewerId = "user1",
+            average = Duration.ZERO,
+            totalReviews = 1,
+            reviewedPrStats = emptyList(),
+            reviewedForPrStats = emptyMap()
+        )
+
+        coEvery { appConfig.get().userIds } returns userIds
+        coEvery { prReviewerStatsService.reviewerStats(any()) } returns reviewerStats
+
+        statsGeneratorApplication.generateReviewerStats()
+
+        userIds.forEach { userId ->
+            coVerify { prReviewerStatsService.reviewerStats(userId) }
+            formatters.forEach { formatter ->
+                verify { formatter.formatReviewerStats(reviewerStats) }
+            }
+        }
+    }
+}