[SPARK-8347][SQL] Add unit tests for abs.

Also addressed code review feedback from #6754

Author: Reynold Xin <rxin@databricks.com>

Closes #6803 from rxin/abs and squashes the following commits:

d07beba [Reynold Xin] [SPARK-8347] Add unit tests for abs.

2 files changed, 19 insertions, 4 deletions

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/HiveTypeCoercion.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/HiveTypeCoercion.scala
index 6ed192360d..e7bf7cc1f1 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/HiveTypeCoercion.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/HiveTypeCoercion.scala
@@ -672,13 +672,13 @@ trait HiveTypeCoercion {
         findTightestCommonTypeToString(left.dataType, right.dataType).map { widestType =>
           val newLeft = if (left.dataType == widestType) left else Cast(left, widestType)
           val newRight = if (right.dataType == widestType) right else Cast(right, widestType)
-          i.makeCopy(Array(pred, newLeft, newRight))
+          If(pred, newLeft, newRight)
         }.getOrElse(i)  // If there is no applicable conversion, leave expression unchanged.
 
       // Convert If(null literal, _, _) into boolean type.
       // In the optimizer, we should short-circuit this directly into false value.
-      case i @ If(pred, left, right) if pred.dataType == NullType =>
-        i.makeCopy(Array(Literal.create(null, BooleanType), left, right))
+      case If(pred, left, right) if pred.dataType == NullType =>
+        If(Literal.create(null, BooleanType), left, right)
     }
   }
 
diff --git a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/ArithmeticExpressionSuite.scala b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/ArithmeticExpressionSuite.scala
index e1afa81a7a..5ff1bca260 100644
--- a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/ArithmeticExpressionSuite.scala
+++ b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/ArithmeticExpressionSuite.scala
@@ -21,7 +21,7 @@ import org.scalatest.Matchers._
 
 import org.apache.spark.SparkFunSuite
 import org.apache.spark.sql.catalyst.dsl.expressions._
-import org.apache.spark.sql.types.{DoubleType, IntegerType}
+import org.apache.spark.sql.types.{Decimal, DoubleType, IntegerType}
 
 
 class ArithmeticExpressionSuite extends SparkFunSuite with ExpressionEvalHelper {
@@ -75,6 +75,21 @@ class ArithmeticExpressionSuite extends SparkFunSuite with ExpressionEvalHelper
     checkDoubleEvaluation(c3 % c2, (1.1 +- 0.001), row)
   }
 
+  test("Abs") {
+    def testAbs(convert: (Int) => Any): Unit = {
+      checkEvaluation(Abs(Literal(convert(0))), convert(0))
+      checkEvaluation(Abs(Literal(convert(1))), convert(1))
+      checkEvaluation(Abs(Literal(convert(-1))), convert(1))
+    }
+    testAbs(_.toByte)
+    testAbs(_.toShort)
+    testAbs(identity)
+    testAbs(_.toLong)
+    testAbs(_.toFloat)
+    testAbs(_.toDouble)
+    testAbs(Decimal(_))
+  }
+
   test("Divide") {
     checkEvaluation(Divide(Literal(2), Literal(1)), 2)
     checkEvaluation(Divide(Literal(1.0), Literal(2.0)), 0.5)