[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().

dev/merge_spark_pr.py

@@ -431,6 +431,8 @@ def main():
 
 if __name__ == "__main__":
     import doctest
-    doctest.testmod()
+    (failure_count, test_count) = doctest.testmod()
+    if failure_count:
+        exit(-1)
     
     main()

python/pyspark/accumulators.py

@@ -264,4 +264,6 @@ def _start_update_server():
 
 if __name__ == "__main__":
     import doctest
-    doctest.testmod()
+    (failure_count, test_count) = doctest.testmod()
+    if failure_count:
+        exit(-1)

python/pyspark/broadcast.py

@@ -115,4 +115,6 @@ class Broadcast(object):
 
 if __name__ == "__main__":
     import doctest
-    doctest.testmod()
+    (failure_count, test_count) = doctest.testmod()
+    if failure_count:
+        exit(-1)

python/pyspark/heapq3.py

@@ -883,6 +883,7 @@ except ImportError:
 
 
 if __name__ == "__main__":
-
     import doctest
-    print(doctest.testmod())
+    (failure_count, test_count) = doctest.testmod()
+    if failure_count:
+        exit(-1)

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)

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)

python/pyspark/shuffle.py

@@ -838,4 +838,6 @@ class ExternalGroupBy(ExternalMerger):
 
 if __name__ == "__main__":
     import doctest
-    doctest.testmod()
+    (failure_count, test_count) = doctest.testmod()
+    if failure_count:
+        exit(-1)

python/pyspark/streaming/util.py

@@ -125,4 +125,6 @@ def rddToFileName(prefix, suffix, timestamp):
 
 if __name__ == "__main__":
     import doctest
-    doctest.testmod()
+    (failure_count, test_count) = doctest.testmod()
+    if failure_count:
+        exit(-1)