Add test case to reproduce panic on Filebeat shutdown

The test is skipped until elastic#964 is addressed.

filebeat/tests/files/logs/.gitignore

@@ -1,2 +1,3 @@
 # Ignore all temp files
 tmp*
+nasa-50k.log

filebeat/tests/system/config/filebeat.yml.j2

@@ -132,7 +132,7 @@ output:
     path: {{ output_file_path|default(beat.working_dir + "/output") }}
     filename: "{{ output_file_filename|default("filebeat") }}"
     rotate_every_kb: 1000
-    #number_of_files: 7
+    number_of_files: 2
 
 {% if filter_enabled %}
 

filebeat/tests/system/test_shutdown.py

@@ -0,0 +1,39 @@
+from filebeat import BaseTest
+import gzip
+import os
+import time
+import unittest
+
+"""
+Tests that Filebeat shuts down cleanly.
+"""
+
+class Test(BaseTest):
+    @unittest.skip("Needs fix from #964")
+    def test_shutdown(self):
+        """
+        Test starting and stopping Filebeat under load.
+        """
+
+        # Uncompress the nasa log file.
+        nasa_log = '../files/logs/nasa-50k.log'
+        if not os.path.isfile(nasa_log):
+            with gzip.open('../files/logs/nasa-50k.log.gz', 'rb') as infile:
+                with open(nasa_log, 'w') as outfile:
+                    for line in infile:
+                        outfile.write(line)
+
+        self.render_config_template(
+                path=os.path.abspath(self.working_dir) + "/log/*",
+                ignoreOlder="1h"
+        )
+
+        os.mkdir(self.working_dir + "/log/")
+        self.copy_files(["logs/nasa-50k.log"],
+                        source_dir="../files",
+                        target_dir="log")
+
+        for i in range(1,5):
+            proc = self.start_beat(logging_args=["-e", "-v"])
+            time.sleep(.5)
+            proc.check_kill_and_wait()

libbeat/tests/system/beat/beat.py

@@ -25,7 +25,7 @@ class Proc(object):
 
     def __init__(self, args, outputfile):
         self.args = args
-        self.output = open(outputfile, "wb")
+        self.output = open(outputfile, "ab")
 
     def start(self):
         self.stdin_read, self.stdin_write = os.pipe()