Add unit test.

Author: viirya

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

@@ -42,6 +42,19 @@ class DataFrameJoinSuite extends QueryTest with SharedSQLContext {
       Row(1, 2, "1", "2") :: Row(2, 3, "2", "3") :: Row(3, 4, "3", "4") :: Nil)
   }
 
+  test("join - join using multiple columns and specifying join type") {
+    val df = Seq(1, 2, 3).map(i => (i, i + 1, i.toString)).toDF("int", "int2", "str")
+    val df2 = Seq(1, 2, 3).map(i => (i, i + 1, (i + 1).toString)).toDF("int", "int2", "str")
+
+    checkAnswer(
+      df.join(df2, Seq("int", "str"), "left"),
+      Row(1, 2, "1", null) :: Row(2, 3, "2", null) :: Row(3, 4, "3", null) :: Nil)
+
+    checkAnswer(
+      df.join(df2, Seq("int", "str"), "right"),
+      Row(null, null, null, 2) :: Row(null, null, null, 3) :: Row(null, null, null, 4) :: Nil)
+  }
+
   test("join - join using self join") {
     val df = Seq(1, 2, 3).map(i => (i, i.toString)).toDF("int", "str")