Fix the error message for Kinesis streaming tests

Author: HyukjinKwon

python/pyspark/streaming/tests.py

@@ -1503,10 +1503,13 @@ def search_flume_assembly_jar():
         return jars[0]
 
 
-def search_kinesis_asl_assembly_jar():
+def _kinesis_asl_assembly_dir():
     SPARK_HOME = os.environ["SPARK_HOME"]
-    kinesis_asl_assembly_dir = os.path.join(SPARK_HOME, "external/kinesis-asl-assembly")
-    jars = search_jar(kinesis_asl_assembly_dir, "spark-streaming-kinesis-asl-assembly")
+    return os.path.join(SPARK_HOME, "external/kinesis-asl-assembly")
+
+
+def search_kinesis_asl_assembly_jar():
+    jars = search_jar(_kinesis_asl_assembly_dir(), "spark-streaming-kinesis-asl-assembly")
     if not jars:
         return None
     elif len(jars) > 1:
@@ -1569,7 +1572,7 @@ def search_kinesis_asl_assembly_jar():
     else:
         raise Exception(
             ("Failed to find Spark Streaming Kinesis assembly jar in %s. "
-             % kinesis_asl_assembly_dir) +
+             % _kinesis_asl_assembly_dir()) +
             "You need to build Spark with 'build/sbt -Pkinesis-asl "
             "assembly/package streaming-kinesis-asl-assembly/assembly'"
             "or 'build/mvn -Pkinesis-asl package' before running this test.")