diff --git a/src/lib/services/analytics/__tests__/ComparativeProgressService.test.ts b/src/lib/services/analytics/__tests__/ComparativeProgressService.test.ts
new file mode 100644
index 000000000..e2a55161b
--- /dev/null
+++ b/src/lib/services/analytics/__tests__/ComparativeProgressService.test.ts
@@ -0,0 +1,29 @@
+import { describe, it, expect, vi, beforeEach } from "vitest"
+import { ComparativeProgressService } from "../ComparativeProgressService"
+
+describe("ComparativeProgressService", () => {
+  let service: ComparativeProgressService
+  let mockLogger: any
+
+  beforeEach(() => {
+    mockLogger = {
+      info: vi.fn(),
+      error: vi.fn()
+    }
+    service = new ComparativeProgressService(mockLogger)
+  })
+
+  it("should return insufficient data when no user progress snapshots exist", async () => {
+    vi.spyOn(service as any, "fetchUserProgressData").mockResolvedValue([])
+
+    const result = await service.analyzeProgress({
+      anonymizedUserId: "test-user",
+      metricName: "test-metric",
+      cohortId: "test-cohort",
+      dateRange: { startDate: "2023-01-01", endDate: "2023-01-31" }
+    })
+
+    expect(result.userProgressSnapshots).toHaveLength(0)
+    expect(result.comparisonInsights.trend).toBe("insufficient_data")
+  })
+})