From b632df3aa4586717ddd08a937e060023c00a2ef4 Mon Sep 17 00:00:00 2001
From: Taro Sato <okomestudio@gmail.com>
Date: Sun, 16 Oct 2016 21:49:10 -0700
Subject: [PATCH] Generate proper empty value for XML/JSON

---
 moto/core/responses.py           | 31 +++++++++++++++++++++++++------
 moto/emr/models.py               | 11 +++++++++--
 tests/test_emr/test_emr_boto3.py | 13 +++++++------
 3 files changed, 41 insertions(+), 14 deletions(-)

diff --git a/moto/core/responses.py b/moto/core/responses.py
index 11b83326e..437937207 100644
--- a/moto/core/responses.py
+++ b/moto/core/responses.py
@@ -1,6 +1,7 @@
 from __future__ import unicode_literals
 import datetime
 import json
+import logging
 import re
 
 from boto.exception import JSONResponseError
@@ -17,6 +18,9 @@ from moto.compat import OrderedDict
 from moto.core.utils import camelcase_to_underscores, method_names_from_class
 
 
+log = logging.getLogger(__name__)
+
+
 def _decode_dict(d):
     decoded = {}
     for key, value in d.items():
@@ -544,11 +548,20 @@ def xml_to_json_response(service_spec, operation, xml, result_node=None):
 
         od = OrderedDict()
         for k, v in value.items():
-            if k.startswith('@') or v is None:
+            if k.startswith('@'):
+                continue
+
+            if k not in spec:
+                # this can happen when with an older version of
+                # botocore for which the node in XML template is not
+                # defined in service spec.
+                log.warning('Field %s is not defined by the botocore version in use', k)
                 continue
 
             if spec[k]['type'] == 'list':
-                if len(spec[k]['member']) == 1:
+                if v is None:
+                    od[k] = []
+                elif len(spec[k]['member']) == 1:
                     if isinstance(v['member'], list):
                         od[k] = transform(v['member'], spec[k]['member'])
                     else:
@@ -560,11 +573,17 @@ def xml_to_json_response(service_spec, operation, xml, result_node=None):
                 else:
                     raise ValueError('Malformatted input')
             elif spec[k]['type'] == 'map':
-                key = from_str(v['entry']['key'], spec[k]['key'])
-                val = from_str(v['entry']['value'], spec[k]['value'])
-                od[k] = {key: val}
+                if v is None:
+                    od[k] = {}
+                else:
+                    key = from_str(v['entry']['key'], spec[k]['key'])
+                    val = from_str(v['entry']['value'], spec[k]['value'])
+                    od[k] = {key: val}
             else:
-                od[k] = transform(v, spec[k])
+                if v is None:
+                    od[k] = None
+                else:
+                    od[k] = transform(v, spec[k])
         return od
 
     dic = xmltodict.parse(xml)
diff --git a/moto/emr/models.py b/moto/emr/models.py
index acc573698..ece4c9979 100644
--- a/moto/emr/models.py
+++ b/moto/emr/models.py
@@ -24,12 +24,19 @@ class FakeBootstrapAction(object):
 
 
 class FakeInstanceGroup(object):
-    def __init__(self, instance_count, instance_role, instance_type, market, name,
-                 id=None, bid_price=None):
+    def __init__(self, instance_count, instance_role, instance_type,
+                 market='ON_DEMAND', name=None, id=None, bid_price=None):
         self.id = id or random_instance_group_id()
 
         self.bid_price = bid_price
         self.market = market
+        if name is None:
+            if instance_role == 'MASTER':
+                name = 'master'
+            elif instance_role == 'CORE':
+                name = 'slave'
+            else:
+                name = 'Task instance group'
         self.name = name
         self.num_instances = instance_count
         self.role = instance_role
diff --git a/tests/test_emr/test_emr_boto3.py b/tests/test_emr/test_emr_boto3.py
index f389c1900..4e297e620 100644
--- a/tests/test_emr/test_emr_boto3.py
+++ b/tests/test_emr/test_emr_boto3.py
@@ -194,8 +194,8 @@ def test_describe_job_flow():
     jf['LogUri'].should.equal(args['LogUri'])
     jf['Name'].should.equal(args['Name'])
     jf['ServiceRole'].should.equal(args['ServiceRole'])
-    jf.shouldnt.have.key('Steps')
-    jf.shouldnt.have.key('SupportedProducts')
+    jf['Steps'].should.equal([])
+    jf['SupportedProducts'].should.equal([])
     jf['VisibleToAllUsers'].should.equal(True)
 
 
@@ -254,7 +254,7 @@ def test_run_job_flow():
     resp['LogUri'].should.equal(args['LogUri'])
     resp['VisibleToAllUsers'].should.equal(args['VisibleToAllUsers'])
     resp['Instances']['NormalizedInstanceHours'].should.equal(0)
-    resp.shouldnt.have.key('Steps')
+    resp['Steps'].should.equal([])
 
 
 @mock_emr
@@ -379,10 +379,11 @@ def test_bootstrap_actions():
         {'Name': 'bs1',
          'ScriptBootstrapAction': {
              'Args': ['arg1', 'arg2'],
-             'Path': 'path/to/script'}},
+             'Path': 's3://path/to/script'}},
         {'Name': 'bs2',
          'ScriptBootstrapAction': {
-             'Path': 'path/to/anotherscript'}}
+             'Args': [],
+             'Path': 's3://path/to/anotherscript'}}
     ]
 
     client = boto3.client('emr', region_name='us-east-1')
@@ -583,4 +584,4 @@ def test_tags():
 
     client.remove_tags(ResourceId=cluster_id, TagKeys=[t['Key'] for t in input_tags])
     resp = client.describe_cluster(ClusterId=cluster_id)['Cluster']
-    resp.shouldnt.have.key('Tags')
+    resp['Tags'].should.equal([])