Add test case.

Author: marmbrus

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

@@ -33,6 +33,12 @@ class DslQuerySuite extends QueryTest {
       testData.collect().toSeq)
   }
 
+  test("repartition") {
+    checkAnswer(
+      testData.select('key).repartition(10).select('key),
+      testData.select('key).collect().toSeq)
+  }
+
   test("agg") {
     checkAnswer(
       testData2.groupBy('a)('a, Sum('b)),