From 45195a8603dd3cb96e91b24145725d391d7879a4 Mon Sep 17 00:00:00 2001
From: Arash Rouhani <arashrk@vng.com.vn>
Date: Wed, 2 Dec 2015 16:16:15 +0700
Subject: [PATCH] Don't print nested stack traces for run() failures

In python3, stack traces seem to report if the raised exception happened
during another exception handling. It will then say something like
"exception happned during handling of above exception". This is nice,
but just cluttery in the case of our tracking_url_callback hack.
---
 luigi/worker.py      |  3 +++
 test/cmdline_test.py | 19 +++++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/luigi/worker.py b/luigi/worker.py
index eff542af8c..cb9c5b04d2 100644
--- a/luigi/worker.py
+++ b/luigi/worker.py
@@ -102,11 +102,14 @@ def __init__(self, task, worker_id, result_queue, random_seed=False, worker_time
         self.timeout_time = time.time() + worker_timeout if worker_timeout else None
 
     def _run_get_new_deps(self):
+        run_again = False
         try:
             task_gen = self.task.run(tracking_url_callback=self.tracking_url_callback)
         except TypeError as ex:
             if 'unexpected keyword argument' not in getattr(ex, 'message', ex.args[0]):
                 raise
+            run_again = True
+        if run_again:
             task_gen = self.task.run()
         if not isinstance(task_gen, types.GeneratorType):
             return None
diff --git a/test/cmdline_test.py b/test/cmdline_test.py
index 8f07e5ac16..eda72503bd 100644
--- a/test/cmdline_test.py
+++ b/test/cmdline_test.py
@@ -84,6 +84,11 @@ class FooSubClass(FooBaseClass):
     pass
 
 
+class ATaskThatFails(luigi.Task):
+    def run(self):
+        raise ValueError()
+
+
 class CmdlineTest(unittest.TestCase):
 
     def setUp(self):
@@ -270,6 +275,20 @@ def test_bin_mentions_misspelled_task(self):
         self.assertTrue(stderr.find(b'FooBaseClass') != -1)
         self.assertTrue(stderr.find(b'--x') != 0)
 
+    def test_stack_trace_has_no_inner(self):
+        """
+        Test that the stack trace for failing tasks are short
+
+        The stack trace shouldn't contain unreasonably much implementation
+        details of luigi In particular it should say that the task is
+        misspelled and not that the local parameters do not exist.
+        """
+        returncode, stdout, stderr = self._run_cmdline(['./bin/luigi', '--module', 'cmdline_test', 'ATaskThatFails', '--local-scheduler', '--no-lock'])
+        print(stdout)
+
+        self.assertFalse(stdout.find(b"run() got an unexpected keyword argument 'tracking_url_callback'") != -1)
+        self.assertFalse(stdout.find(b'During handling of the above exception, another exception occurred') != -1)
+
 
 if __name__ == '__main__':
     # Needed for one of the tests