diff --git a/requirements.txt b/requirements.txt
index 8e75573..e60629a 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -10,5 +10,6 @@ PyYAML
 rdflib
 rdflib-jsonld
 numpy
-scipy
+scip
 scikit-learn
+responses
diff --git a/senpy/client.py b/senpy/client.py
index 892e77a..43414f8 100644
--- a/senpy/client.py
+++ b/senpy/client.py
@@ -13,7 +13,7 @@ class Client(object):
         return self.request('/', method=method, input=input, **kwargs)
 
     def evaluate(self, input, method='GET', **kwargs):
-        return self.request('/evaluate', method = method, input=input, **kwargs)
+        return self.request('/evaluate', method=method, input=input, **kwargs)
 
     def plugins(self, *args, **kwargs):
         resp = self.request(path='/plugins').plugins
@@ -24,7 +24,7 @@ class Client(object):
         return {d.name: d for d in resp}
 
     def request(self, path=None, method='GET', **params):
-        url = '{}{}'.format(self.endpoint, path)
+        url = '{}{}'.format(self.endpoint.rstrip('/'), path)
         response = requests.request(method=method, url=url, params=params)
         try:
             resp = models.from_dict(response.json())
diff --git a/senpy/plugins/__init__.py b/senpy/plugins/__init__.py
index 84d4860..6a0e1ae 100644
--- a/senpy/plugins/__init__.py
+++ b/senpy/plugins/__init__.py
@@ -24,6 +24,7 @@ import nltk
 from .. import models, utils
 from .. import api
 from .. import gsitk_compat
+from .. import testing
 
 
 logger = logging.getLogger(__name__)
@@ -143,14 +144,23 @@ class Plugin(with_metaclass(PluginMeta, models.Plugin)):
                 self.log.warn('Test case failed:\n{}'.format(pprint.pformat(case)))
                 raise
 
-    def test_case(self, case):
+    def test_case(self, case, mock=testing.MOCK_REQUESTS):
         entry = models.Entry(case['entry'])
         given_parameters = case.get('params', case.get('parameters', {}))
         expected = case.get('expected', None)
         should_fail = case.get('should_fail', False)
+        responses = case.get('responses', [])
+
         try:
             params = api.parse_params(given_parameters, self.extra_params)
-            res = list(self.analyse_entries([entry, ], params))
+
+            method = partial(self.analyse_entries, [entry, ], params)
+
+            if mock:
+                res = list(method())
+            else:
+                with testing.patch_all_requests(responses):
+                    res = list(method())
 
             if not isinstance(expected, list):
                 expected = [expected]
diff --git a/senpy/plugins/sentiment/sentiment140/sentiment140_plugin.py b/senpy/plugins/sentiment/sentiment140/sentiment140_plugin.py
index 1057079..d40fd15 100644
--- a/senpy/plugins/sentiment/sentiment140/sentiment140_plugin.py
+++ b/senpy/plugins/sentiment/sentiment140/sentiment140_plugin.py
@@ -4,6 +4,8 @@ import json
 from senpy.plugins import SentimentPlugin
 from senpy.models import Sentiment
 
+ENDPOINT = 'http://www.sentiment140.com/api/bulkClassifyJson'
+
 
 class Sentiment140(SentimentPlugin):
     '''Connects to the sentiment140 free API: http://sentiment140.com'''
@@ -26,7 +28,7 @@ class Sentiment140(SentimentPlugin):
 
     def analyse_entry(self, entry, params):
         lang = params["language"]
-        res = requests.post("http://www.sentiment140.com/api/bulkClassifyJson",
+        res = requests.post(ENDPOINT,
                             json.dumps({
                                 "language": lang,
                                 "data": [{
@@ -52,18 +54,6 @@ class Sentiment140(SentimentPlugin):
         entry.language = lang
         yield entry
 
-    def test(self, *args, **kwargs):
-        '''
-        To avoid calling the sentiment140 API, we will mock the results
-        from requests.
-        '''
-        from senpy.testing import patch_requests
-        expected = {"data": [{"polarity": 4}]}
-        with patch_requests(expected) as (request, response):
-            super(Sentiment140, self).test(*args, **kwargs)
-            assert request.called
-            assert response.json.called
-
     test_cases = [
         {
             'entry': {
@@ -77,6 +67,9 @@ class Sentiment140(SentimentPlugin):
                         'marl:hasPolarity': 'marl:Positive',
                     }
                 ]
-            }
+            },
+            'responses': [{'url': ENDPOINT,
+                           'method': 'POST',
+                           'json': {'data': [{'polarity': 4}]}}]
         }
     ]
diff --git a/senpy/testing.py b/senpy/testing.py
index 9190637..6777a0d 100644
--- a/senpy/testing.py
+++ b/senpy/testing.py
@@ -1,36 +1,31 @@
-try:
-    from unittest.mock import patch, MagicMock
-except ImportError:
-    from mock import patch, MagicMock
-
 from past.builtins import basestring
 
-
-import json
-from contextlib import contextmanager
+import os
+import responses as requestmock
 
 from .models import BaseModel
 
 
-@contextmanager
-def patch_requests(value, code=200):
-    success = MagicMock()
-    if isinstance(value, BaseModel):
-        value = value.jsonld()
-    if not isinstance(value, basestring):
-        data = json.dumps(value)
-    else:
-        data = value
+MOCK_REQUESTS = os.environ.get('MOCK_REQUESTS', '').lower() in ['no', 'false']
+
 
-    success.json.return_value = value
+def patch_all_requests(responses):
 
-    success.status_code = code
-    success.content = data
-    success.text = data
+    patched = requestmock.RequestsMock()
 
-    method_mocker = MagicMock()
-    method_mocker.return_value = success
-    with patch.multiple('requests', request=method_mocker,
-                        get=method_mocker, post=method_mocker):
-        yield method_mocker, success
-        assert method_mocker.called
+    for response in responses or []:
+        args = response.copy()
+        if 'json' in args and isinstance(args['json'], BaseModel):
+            args['json'] = args['json'].jsonld()
+        args['method'] = getattr(requestmock, args.get('method', 'GET'))
+        patched.add(**args)
+    return patched
+
+
+def patch_requests(url, response, method='GET', status=200):
+    args = {'url': url, 'method': method, 'status': status}
+    if isinstance(response, basestring):
+        args['body'] = response
+    else:
+        args['json'] = response
+    return patch_all_requests([args])
diff --git a/tests/test_client.py b/tests/test_client.py
index d2a48f8..710f894 100644
--- a/tests/test_client.py
+++ b/tests/test_client.py
@@ -14,22 +14,15 @@ class ModelsTest(TestCase):
     def test_client(self):
         endpoint = 'http://dummy/'
         client = Client(endpoint)
-        with patch_requests(Results()) as (request, response):
+        with patch_requests('http://dummy/', Results()):
             resp = client.analyse('hello')
             assert isinstance(resp, Results)
-        request.assert_called_with(
-            url=endpoint + '/', method='GET', params={'input': 'hello'})
-        with patch_requests(Error('Nothing')) as (request, response):
+        with patch_requests('http://dummy/', Error('Nothing')):
             try:
                 client.analyse(input='hello', algorithm='NONEXISTENT')
                 raise Exception('Exceptions should be raised. This is not golang')
             except Error:
                 pass
-        request.assert_called_with(
-            url=endpoint + '/',
-            method='GET',
-            params={'input': 'hello',
-                    'algorithm': 'NONEXISTENT'})
 
     def test_plugins(self):
         endpoint = 'http://dummy/'
@@ -37,11 +30,8 @@ class ModelsTest(TestCase):
         plugins = Plugins()
         p1 = AnalysisPlugin({'name': 'AnalysisP1', 'version': 0, 'description': 'No'})
         plugins.plugins = [p1, ]
-        with patch_requests(plugins) as (request, response):
+        with patch_requests('http://dummy/plugins', plugins):
             response = client.plugins()
             assert isinstance(response, dict)
             assert len(response) == 1
             assert "AnalysisP1" in response
-        request.assert_called_with(
-            url=endpoint + '/plugins', method='GET',
-            params={})
diff --git a/tests/test_test.py b/tests/test_test.py
index c1d2d5b..08d5355 100644
--- a/tests/test_test.py
+++ b/tests/test_test.py
@@ -5,28 +5,29 @@ import json
 from senpy.testing import patch_requests
 from senpy.models import Results
 
+ENDPOINT = 'http://example.com'
+
 
 class TestTest(TestCase):
     def test_patch_text(self):
-        with patch_requests('hello'):
-            r = requests.get('http://example.com')
+        with patch_requests(ENDPOINT, 'hello'):
+            r = requests.get(ENDPOINT)
             assert r.text == 'hello'
-            assert r.content == 'hello'
 
     def test_patch_json(self):
         r = Results()
-        with patch_requests(r):
-            res = requests.get('http://example.com')
-            assert res.content == json.dumps(r.jsonld())
+        with patch_requests(ENDPOINT, r):
+            res = requests.get(ENDPOINT)
+            assert res.text == json.dumps(r.jsonld())
             js = res.json()
             assert js
             assert js['@type'] == r['@type']
 
     def test_patch_dict(self):
         r = {'nothing': 'new'}
-        with patch_requests(r):
-            res = requests.get('http://example.com')
-            assert res.content == json.dumps(r)
+        with patch_requests(ENDPOINT, r):
+            res = requests.get(ENDPOINT)
+            assert res.text == json.dumps(r)
             js = res.json()
             assert js
             assert js['nothing'] == 'new'