Tests for applySchema.

Author: yhuai

sql/core/src/main/scala/org/apache/spark/sql/SQLContext.scala

@@ -97,6 +97,8 @@ class SQLContext(@transient val sparkContext: SparkContext)
    */
   @DeveloperApi
   def applySchema(rowRDD: RDD[Row], schema: StructType): SchemaRDD = {
+    // TODO: use MutableProjection when rowRDD is another SchemaRDD and the applied
+    // schema differs from the existing schema on any field data type.
     val logicalPlan = SparkLogicalPlan(ExistingRdd(schema.toAttributes, rowRDD))
     new SchemaRDD(this, logicalPlan)
   }

sql/core/src/test/scala/org/apache/spark/sql/SQLQuerySuite.scala

@@ -431,4 +431,36 @@ class SQLQuerySuite extends QueryTest {
     )
     clear()
   }
+
+  test("apply schema") {
+    val schema = StructType(
+      StructField("f1", IntegerType, false) ::
+      StructField("f2", StringType, false) ::
+      StructField("f3", BooleanType, false) ::
+      StructField("f4", IntegerType, true) :: Nil)
+
+    val rowRDD = unparsedStrings.map { r =>
+      val values = r.split(",").map(_.trim)
+      val v4 = try values(3).toInt catch {
+        case _: NumberFormatException => null
+      }
+      Row(values(0).toInt, values(1), values(2).toBoolean, v4)
+    }
+
+    val schemaRDD = applySchema(rowRDD, schema)
+    schemaRDD.registerAsTable("applySchema")
+    checkAnswer(
+      sql("SELECT * FROM applySchema"),
+      (1, "A1", true, null) ::
+      (2, "B2", false, null) ::
+      (3, "C3", true, null) ::
+      (4, "D4", true, 2147483644) :: Nil)
+
+    checkAnswer(
+      sql("SELECT f1, f4 FROM applySchema"),
+      (1, null) ::
+      (2, null) ::
+      (3, null) ::
+      (4, 2147483644) :: Nil)
+  }
 }

sql/core/src/test/scala/org/apache/spark/sql/TestData.scala

@@ -128,4 +128,11 @@ object TestData {
 
   case class TableName(tableName: String)
   TestSQLContext.sparkContext.parallelize(TableName("test") :: Nil).registerAsTable("tableName")
+
+  val unparsedStrings =
+    TestSQLContext.sparkContext.parallelize(
+      "1, A1, true, null" ::
+      "2, B2, false, null" ::
+      "3, C3, true, null" ::
+      "4, D4, true, 2147483644" :: Nil)
 }