MGHawes commented on a change in pull request #25575: [SPARK-28818][SQL]
Respect source column nullability in the arrays created by `freqItems()`
URL: https://github.com/apache/spark/pull/25575#discussion_r318357528
##########
File path:
sql/core/src/test/scala/org/apache/spark/sql/DataFrameStatSuite.scala
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@@ -366,6 +366,27 @@ class DataFrameStatSuite extends QueryTest with
SharedSparkSession {
}
}
+ test("SPARK-28818: Respect original column nullability in `freqItems`") {
+ val rows = spark.sparkContext.parallelize(
+ Seq(Row("1", "a"), Row("2", null), Row("3", "b"))
+ )
+ val schema = StructType(Seq(
+ StructField("non_null", StringType, false),
+ StructField("nullable", StringType, true)
+ ))
+ val df = spark.createDataFrame(rows, schema)
+
+ val result = df.stat.freqItems(df.columns)
+
+ val nonNullableFreqItems =
result.schema("non_null_freqItems").dataType.asInstanceOf[ArrayType]
+ val nullableFreqItems =
result.schema("nullable_freqItems").dataType.asInstanceOf[ArrayType]
+
+ assert(nonNullableFreqItems.containsNull == false)
+ assert(nullableFreqItems.containsNull == true)
+ // Original bug was a NullPointerException exception caused by calling
collect(), test for this
+ val resultRows = result.collect()
Review comment:
I can if people want me to? My general rule is only to assert exactly what
the unit test is trying to test. In this case a specific bug. If unit tests are
overlapping it can be very hard to tell what exactly is failing and where a
regression has been introduced because all test fail at once.
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