✅ Add statistical tests

Author: LuizFCDuarte

test/test_statistical_tests.jl

@@ -181,6 +181,11 @@ end
         @test ocsb_result["seasonal_difference"] == ocsb_datasets["airpassengers.csv"]["D"]
         @test isapprox(ocsb_result["test_statistic"], ocsb_datasets["airpassengers.csv"]["test_stat"], atol=5e-3)
 
+        airpassengersLog = log.(values(airpassengers))
+        ocsb_result = Sarimax.ocsb_test(airpassengersLog;max_lag=3)
+        @test ocsb_result["seasonal_difference"] == ocsb_datasets["log_airpassengers.csv"]["D"]
+        @test isapprox(ocsb_result["test_statistic"], ocsb_datasets["log_airpassengers.csv"]["test_stat"], atol=5e-3)
+
         gdpc1 = loadDataset(GDPC1)
         ocsb_result = Sarimax.ocsb_test(values(gdpc1);max_lag=3)
         @test ocsb_result["seasonal_difference"] == ocsb_datasets["GDPC1.csv"]["D"]