test: add asset level service unit tests

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend/services/assetService/service/asset_level_service_test.go

@@ -0,0 +1,28 @@
+package service
+
+import (
+	"testing"
+)
+
+func TestCalculateBuff(t *testing.T) {
+	tests := []struct {
+		likeCount int
+		expected   int
+	}{
+		{0, 0},
+		{4, 0},
+		{5, 10},
+		{9, 10},
+		{10, 20},
+		{29, 20},
+		{30, 30},
+		{100, 30},
+	}
+
+	for _, tt := range tests {
+		result := CalculateBuff(tt.likeCount)
+		if result != tt.expected {
+			t.Errorf("CalculateBuff(%d) = %d, want %d", tt.likeCount, result, tt.expected)
+		}
+	}
+}