[SPARK-11270][STREAMING] Add improved equality testing for TopicAndPa…

…rtition from the Kafka Streaming API

jerryshao tdas

I know this is kind of minor, and I know you all are busy, but this brings this class in line with the `OffsetRange` class, and makes tests a little more concise.

Instead of doing something like:
```
assert topic_and_partition_instance._topic == "foo"
assert topic_and_partition_instance._partition == 0
```

You can do something like:
```
assert topic_and_partition_instance == TopicAndPartition("foo", 0)
```

Before:
```
>>> from pyspark.streaming.kafka import TopicAndPartition
>>> TopicAndPartition("foo", 0) == TopicAndPartition("foo", 0)
False
```

After:
```
>>> from pyspark.streaming.kafka import TopicAndPartition
>>> TopicAndPartition("foo", 0) == TopicAndPartition("foo", 0)
True
```

I couldn't find any tests - am I missing something?

Author: Nick Evans <me@nicolasevans.org>

Closes apache#9236 from manygrams/topic_and_partition_equality.

(cherry picked from commit 8f888ee)
Signed-off-by: Tathagata Das <tathagata.das1565@gmail.com>

python/pyspark/streaming/kafka.py

@@ -254,6 +254,16 @@ def __init__(self, topic, partition):
     def _jTopicAndPartition(self, helper):
         return helper.createTopicAndPartition(self._topic, self._partition)
 
+    def __eq__(self, other):
+        if isinstance(other, self.__class__):
+            return (self._topic == other._topic
+                    and self._partition == other._partition)
+        else:
+            return False
+
+    def __ne__(self, other):
+        return not self.__eq__(other)
+
 
 class Broker(object):
     """

python/pyspark/streaming/tests.py

@@ -887,6 +887,16 @@ def transformWithOffsetRanges(rdd):
 
         self.assertEqual(offsetRanges, [OffsetRange(topic, 0, long(0), long(6))])
 
+    def test_topic_and_partition_equality(self):
+        topic_and_partition_a = TopicAndPartition("foo", 0)
+        topic_and_partition_b = TopicAndPartition("foo", 0)
+        topic_and_partition_c = TopicAndPartition("bar", 0)
+        topic_and_partition_d = TopicAndPartition("foo", 1)
+
+        self.assertEqual(topic_and_partition_a, topic_and_partition_b)
+        self.assertNotEqual(topic_and_partition_a, topic_and_partition_c)
+        self.assertNotEqual(topic_and_partition_a, topic_and_partition_d)
+
 
 class FlumeStreamTests(PySparkStreamingTestCase):
     timeout = 20  # seconds