diff --git a/swh/core/api/tests/test_rpc_client_server.py b/swh/core/api/tests/test_rpc_client_server.py
new file mode 100644
--- /dev/null
+++ b/swh/core/api/tests/test_rpc_client_server.py
@@ -0,0 +1,83 @@
+# Copyright (C) 2018-2019  The Software Heritage developers
+# See the AUTHORS file at the top-level directory of this distribution
+# License: GNU General Public License version 3, or any later version
+# See top-level LICENSE file for more information
+
+import pytest
+
+import requests
+from swh.core.api import remote_api_endpoint, RPCServerApp, RPCClient
+from swh.core.api import error_handler, encode_data_server
+
+
+class RPCTest:
+    @remote_api_endpoint('endpoint_url')
+    def endpoint(self, test_data, db=None, cur=None):
+        assert test_data == 'spam'
+        return 'egg'
+
+    @remote_api_endpoint('path/to/endpoint')
+    def something(self, data, db=None, cur=None):
+        return data
+
+
+class RPCTest2:
+    @remote_api_endpoint('endpoint_url')
+    def endpoint(self, test_data, db=None, cur=None):
+        assert test_data == 'spam'
+        return 'egg'
+
+    @remote_api_endpoint('path/to/endpoint')
+    def something(self, data, db=None, cur=None):
+        return data
+
+    @remote_api_endpoint('not_on_server')
+    def not_on_server(self, db=None, cur=None):
+        return 'ok'
+
+
+class RPCTestClient(RPCClient):
+    backend_class = RPCTest2
+
+
+@pytest.fixture
+def app():
+    # needed by the 'swh_rpc_adapter' fixture (defined in pytest_plugin.py)
+    application = RPCServerApp('testapp', backend_class=RPCTest)
+    @application.errorhandler(Exception)
+    def my_error_handler(exception):
+        return error_handler(exception, encode_data_server)
+    return application
+
+
+@pytest.fixture
+def rpc_client(swh_rpc_adapter):
+    url = 'mock://example.com'
+    cli = RPCTestClient(url=url)
+    cli.session = requests.Session()
+    cli.session.mount(url, swh_rpc_adapter)
+    return cli
+
+
+def test_api_client_endpoint_missing(rpc_client):
+    with pytest.raises(AttributeError):
+        rpc_client.missing(data='whatever')
+
+
+def test_api_server_endpoint_missing(rpc_client):
+    with pytest.raises(Exception, match='404 Not Found'):
+        rpc_client.not_on_server()
+
+
+def test_api_endpoint_kwargs(rpc_client):
+    res = rpc_client.something(data='whatever')
+    assert res == 'whatever'
+    res = rpc_client.endpoint(test_data='spam')
+    assert res == 'egg'
+
+
+def test_api_endpoint_args(rpc_client):
+    res = rpc_client.something('whatever')
+    assert res == 'whatever'
+    res = rpc_client.endpoint('spam')
+    assert res == 'egg'
diff --git a/swh/core/pytest_plugin.py b/swh/core/pytest_plugin.py
--- a/swh/core/pytest_plugin.py
+++ b/swh/core/pytest_plugin.py
@@ -6,12 +6,17 @@
 import logging
 import re
 import pytest
+import requests
 
 from functools import partial
 from os import path
 from typing import Dict, List, Optional
 from urllib.parse import urlparse
 
+from requests.adapters import BaseAdapter
+from requests.structures import CaseInsensitiveDict
+from requests.utils import get_encoding_from_headers
+
 
 logger = logging.getLogger(__name__)
 
@@ -178,6 +183,56 @@
     has_multi_visit=True)
 
 
+@pytest.yield_fixture
+def swh_rpc_adapter(app):
+    """Fixture that generates a requests.Adapter instance that
+    can be used to test client/servers code based on swh.core.api classes.
+
+    See swh/core/api/tests/test_rpc_client_server.py for an example of usage.
+    """
+    with app.test_client() as client:
+        yield RPCTestAdapter(client)
+
+
+class RPCTestAdapter(BaseAdapter):
+    def __init__(self, client):
+        self._client = client
+
+    def build_response(self, req, resp):
+        response = requests.Response()
+
+        # Fallback to None if there's no status_code, for whatever reason.
+        response.status_code = resp.status_code
+
+        # Make headers case-insensitive.
+        response.headers = CaseInsensitiveDict(getattr(resp, 'headers', {}))
+
+        # Set encoding.
+        response.encoding = get_encoding_from_headers(response.headers)
+        response.raw = resp
+        response.reason = response.raw.status
+
+        if isinstance(req.url, bytes):
+            response.url = req.url.decode('utf-8')
+        else:
+            response.url = req.url
+
+        # Give the Response some context.
+        response.request = req
+        response.connection = self
+        response._content = resp.data
+
+        return response
+
+    def send(self, request, **kw):
+        resp = self._client.open(
+            request.url, method=request.method,
+            headers=request.headers.items(),
+            data=request.body,
+            )
+        return self.build_response(request, resp)
+
+
 @pytest.yield_fixture
 def flask_app_client(app):
     with app.test_client() as client: