diff --git a/sql/core/src/test/scala/org/apache/spark/sql/QueryTest.scala b/sql/core/src/test/scala/org/apache/spark/sql/QueryTest.scala
index 343758674641b85c4c0a5f13d98642b3ef1381e6..304881d4a4bdd528aa2365aaf7013e112cee7728 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/QueryTest.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/QueryTest.scala
@@ -402,7 +402,7 @@ object QueryTest {
         s"""
         |Results do not match for query:
         |Timezone: ${TimeZone.getDefault}
-        |Timezone Env: ${sys.env("TZ")}
+        |Timezone Env: ${sys.env.getOrElse("TZ", "")}
         |
         |${df.queryExecution}
         |== Results ==
@@ -483,3 +483,11 @@ object QueryTest {
     }
   }
 }
+
+class QueryTestSuite extends QueryTest with test.SharedSQLContext {
+  test("SPARK-16940: checkAnswer should raise TestFailedException for wrong results") {
+    intercept[org.scalatest.exceptions.TestFailedException] {
+      checkAnswer(sql("SELECT 1"), Row(2) :: Nil)
+    }
+  }
+}