[SPARK-8652] [PYSPARK] Check return value for all uses of doctest.testmod()

This patch addresses a critical issue in the PySpark tests:

Several of our Python modules' `__main__` methods call `doctest.testmod()` in order to run doctests but forget to check and handle its return value. As a result, some PySpark test failures can go unnoticed because they will not fail the build.

Fortunately, there was only one test failure which was masked by this bug: a `pyspark.profiler` doctest was failing due to changes in RDD pipelining.

Author: Josh Rosen <joshrosen@databricks.com>

Closes #7032 from JoshRosen/testmod-fix and squashes the following commits:

60dbdc0 [Josh Rosen] Account for int vs. long formatting change in Python 3
8b8d80a [Josh Rosen] Fix failing test.
e6423f9 [Josh Rosen] Check return code for all uses of doctest.testmod().

1 files changed, 5 insertions, 3 deletions

diff --git a/python/pyspark/serializers.py b/python/pyspark/serializers.py
index 7f9d0a338d..411b4dbf48 100644
--- a/python/pyspark/serializers.py
+++ b/python/pyspark/serializers.py
@@ -44,8 +44,8 @@ which contains two batches of two objects:
 
 >>> rdd.glom().collect()
 [[0, 1, 2, 3], [4, 5, 6, 7], [8, 9, 10, 11], [12, 13, 14, 15]]
->>> rdd._jrdd.count()
-8L
+>>> int(rdd._jrdd.count())
+8
 >>> sc.stop()
 """
 
@@ -556,4 +556,6 @@ def write_with_length(obj, stream):
 
 if __name__ == '__main__':
     import doctest
-    doctest.testmod()
+    (failure_count, test_count) = doctest.testmod()
+    if failure_count:
+        exit(-1)