Add unit test for table size stat.

Author: Marcelo Vanzin

sql/core/src/test/scala/org/apache/spark/sql/execution/columnar/InMemoryColumnarQuerySuite.scala

@@ -232,4 +232,18 @@ class InMemoryColumnarQuerySuite extends QueryTest with SharedSQLContext {
     val columnTypes2 = List.fill(length2)(IntegerType)
     val columnarIterator2 = GenerateColumnAccessor.generate(columnTypes2)
   }
+
+  test("SPARK-17549: cached table size should be correctly calculated") {
+    val data = spark.sparkContext.parallelize(1 to 10, 5).toDF()
+    val plan = spark.sessionState.executePlan(data.logicalPlan).sparkPlan
+    val cached = InMemoryRelation(true, 5, MEMORY_ONLY, plan, None)
+
+    // Materialize the data.
+    val expectedAnswer = data.collect()
+    checkAnswer(cached, expectedAnswer)
+
+    // Check that the right size was calculated.
+    assert(cached.batchStats.value === expectedAnswer.size * INT.defaultSize)
+  }
+
 }