[SPARK-8446] [SQL] Add helper functions for testing SparkPlan physical operators

sql/core/src/test/scala/org/apache/spark/sql/execution/SortSuite.scala

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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.sql.execution
+
+import org.apache.spark.sql.catalyst.dsl.expressions._
+
+class SortSuite extends SparkPlanTest {
+
+  // This test was originally added as an example of how to use [[SparkPlanTest]];
+  // it's not designed to be a comprehensive test of ExternalSort.
+  test("basic sorting using ExternalSort") {
+
+    val input = Seq(
+      ("Hello", 4, 2.0),
+      ("Hello", 1, 1.0),
+      ("World", 8, 3.0)
+    )
+
+    checkAnswer(
+      input.toDF("a", "b", "c"),
+      ExternalSort('a.asc :: 'b.asc :: Nil, global = false, _: SparkPlan),
+      input.sorted)
+
+    checkAnswer(
+      input.toDF("a", "b", "c"),
+      ExternalSort('b.asc :: 'a.asc :: Nil, global = false, _: SparkPlan),
+      input.sortBy(t => (t._2, t._1)))
+  }
+}

sql/core/src/test/scala/org/apache/spark/sql/execution/SparkPlanTest.scala

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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.sql.execution
+
+import scala.language.implicitConversions
+import scala.reflect.runtime.universe.TypeTag
+import scala.util.control.NonFatal
+
+import org.apache.spark.SparkFunSuite
+
+import org.apache.spark.sql.catalyst.analysis.UnresolvedAttribute
+import org.apache.spark.sql.catalyst.expressions.BoundReference
+import org.apache.spark.sql.catalyst.util._
+
+import org.apache.spark.sql.test.TestSQLContext
+import org.apache.spark.sql.{DataFrameHolder, Row, DataFrame}
+
+/**
+ * Base class for writing tests for individual physical operators. For an example of how this
+ * class's test helper methods can be used, see [[SortSuite]].
+ */
+class SparkPlanTest extends SparkFunSuite {
+
+  /**
+   * Creates a DataFrame from a local Seq of Product.
+   */
+  implicit def localSeqToDataFrameHolder[A <: Product : TypeTag](data: Seq[A]): DataFrameHolder = {
+    TestSQLContext.implicits.localSeqToDataFrameHolder(data)
+  }
+
+  /**
+   * Runs the plan and makes sure the answer matches the expected result.
+   * @param input the input data to be used.
+   * @param planFunction a function which accepts the input SparkPlan and uses it to instantiate
+   *                     the physical operator that's being tested.
+   * @param expectedAnswer the expected result in a [[Seq]] of [[Row]]s.
+   */
+  protected def checkAnswer(
+      input: DataFrame,
+      planFunction: SparkPlan => SparkPlan,
+      expectedAnswer: Seq[Row]): Unit = {
+    SparkPlanTest.checkAnswer(input, planFunction, expectedAnswer) match {
+      case Some(errorMessage) => fail(errorMessage)
+      case None =>
+    }
+  }
+
+  /**
+   * Runs the plan and makes sure the answer matches the expected result.
+   * @param input the input data to be used.
+   * @param planFunction a function which accepts the input SparkPlan and uses it to instantiate
+   *                     the physical operator that's being tested.
+   * @param expectedAnswer the expected result in a [[Seq]] of [[Product]]s.
+   */
+  protected def checkAnswer[A <: Product : TypeTag](
+      input: DataFrame,
+      planFunction: SparkPlan => SparkPlan,
+      expectedAnswer: Seq[A]): Unit = {
+    val expectedRows = expectedAnswer.map(Row.fromTuple)
+    SparkPlanTest.checkAnswer(input, planFunction, expectedRows) match {
+      case Some(errorMessage) => fail(errorMessage)
+      case None =>
+    }
+  }
+}
+
+/**
+ * Helper methods for writing tests of individual physical operators.
+ */
+object SparkPlanTest {
+
+  /**
+   * Runs the plan and makes sure the answer matches the expected result.
+   * @param input the input data to be used.
+   * @param planFunction a function which accepts the input SparkPlan and uses it to instantiate
+   *                     the physical operator that's being tested.
+   * @param expectedAnswer the expected result in a [[Seq]] of [[Row]]s.
+   */
+  def checkAnswer(
+      input: DataFrame,
+      planFunction: SparkPlan => SparkPlan,
+      expectedAnswer: Seq[Row]): Option[String] = {
+
+    val outputPlan = planFunction(input.queryExecution.sparkPlan)
+
+    // A very simple resolver to make writing tests easier. In contrast to the real resolver
+    // this is always case sensitive and does not try to handle scoping or complex type resolution.
+    val resolvedPlan = outputPlan transform {
+      case plan: SparkPlan =>
+        val inputMap = plan.children.flatMap(_.output).zipWithIndex.map {
+          case (a, i) =>
+            (a.name, BoundReference(i, a.dataType, a.nullable))
+        }.toMap
+
+        plan.transformExpressions {
+          case UnresolvedAttribute(Seq(u)) =>
+            inputMap.getOrElse(u,
+              sys.error(s"Invalid Test: Cannot resolve $u given input $inputMap"))
+        }
+    }
+
+    def prepareAnswer(answer: Seq[Row]): Seq[Row] = {
+      // Converts data to types that we can do equality comparison using Scala collections.
+      // For BigDecimal type, the Scala type has a better definition of equality test (similar to
+      // Java's java.math.BigDecimal.compareTo).
+      // For binary arrays, we convert it to Seq to avoid of calling java.util.Arrays.equals for
+      // equality test.
+      // This function is copied from Catalyst's QueryTest
+      val converted: Seq[Row] = answer.map { s =>
+        Row.fromSeq(s.toSeq.map {
+          case d: java.math.BigDecimal => BigDecimal(d)
+          case b: Array[Byte] => b.toSeq
+          case o => o
+        })
+      }
+      converted.sortBy(_.toString())
+    }
+
+    val sparkAnswer: Seq[Row] = try {
+      resolvedPlan.executeCollect().toSeq
+    } catch {
+      case NonFatal(e) =>
+        val errorMessage =
+          s"""
+             | Exception thrown while executing Spark plan:
+             | $outputPlan
+             | == Exception ==
+             | $e
+             | ${org.apache.spark.sql.catalyst.util.stackTraceToString(e)}
+          """.stripMargin
+        return Some(errorMessage)
+    }
+
+    if (prepareAnswer(expectedAnswer) != prepareAnswer(sparkAnswer)) {
+      val errorMessage =
+        s"""
+           | Results do not match for Spark plan:
+           | $outputPlan
+           | == Results ==
+           | ${sideBySide(
+              s"== Correct Answer - ${expectedAnswer.size} ==" +:
+              prepareAnswer(expectedAnswer).map(_.toString()),
+              s"== Spark Answer - ${sparkAnswer.size} ==" +:
+              prepareAnswer(sparkAnswer).map(_.toString())).mkString("\n")}
+      """.stripMargin
+      return Some(errorMessage)
+    }
+
+    None
+  }
+}
+