[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, 6 insertions, 2 deletions

diff --git a/python/pyspark/profiler.py b/python/pyspark/profiler.py
index d18daaabfc..44d17bd629 100644
--- a/python/pyspark/profiler.py
+++ b/python/pyspark/profiler.py
@@ -90,9 +90,11 @@ class Profiler(object):
     >>> sc = SparkContext('local', 'test', conf=conf, profiler_cls=MyCustomProfiler)
     >>> sc.parallelize(range(1000)).map(lambda x: 2 * x).take(10)
     [0, 2, 4, 6, 8, 10, 12, 14, 16, 18]
+    >>> sc.parallelize(range(1000)).count()
+    1000
     >>> sc.show_profiles()
     My custom profiles for RDD:1
-    My custom profiles for RDD:2
+    My custom profiles for RDD:3
     >>> sc.stop()
     """
 
@@ -169,4 +171,6 @@ class BasicProfiler(Profiler):
 
 if __name__ == "__main__":
     import doctest
-    doctest.testmod()
+    (failure_count, test_count) = doctest.testmod()
+    if failure_count:
+        exit(-1)