fix unit test

Author: actuaryzhang

R/pkg/tests/fulltests/test_mllib_regression.R

@@ -174,6 +174,7 @@ test_that("spark.glm summary", {
   expect_equal(stats$aic, rStats$aic)
 
   # Test spark.glm works with offset
+  training <- suppressWarnings(createDataFrame(iris))
   stats <- summary(spark.glm(training, Sepal_Width ~ Sepal_Length + Species,
                              family = poisson(), offsetCol = "Petal_Length"))
   rStats <- suppressWarnings(summary(glm(Sepal.Width ~ Sepal.Length + Species,