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
@@ -11,7 +11,7 @@
 from functools import partial
 from os import path
 from typing import Dict, List, Optional
-from urllib.parse import urlparse
+from urllib.parse import urlparse, unquote
 
 from requests.adapters import BaseAdapter
 from requests.structures import CaseInsensitiveDict
@@ -26,10 +26,12 @@
 MAX_VISIT_FILES = 10
 
 
-def get_response_cb(request, context, datadir,
-                    ignore_urls: List[str] = [],
-                    visits: Optional[Dict] = None):
-    """Mount point callback to fetch on disk the request's content.
+def get_response_cb(
+        request: requests.Request, context, datadir,
+        ignore_urls: List[str] = [],
+        visits: Optional[Dict] = None):
+    """Mount point callback to fetch on disk the request's content. The request
+    urls provided are url decoded first to resolve the associated file on disk.
 
     This is meant to be used as 'body' argument of the requests_mock.get()
     method.
@@ -65,9 +67,10 @@
         datadir/http_nowhere.com/path_to_resource,a=b,c=d
 
     Args:
-        request (requests.Request): Object requests
+        request: Object requests
         context (requests.Context): Object holding response metadata
             information (status_code, headers, etc...)
+        datadir: Data files path
         ignore_urls: urls whose status response should be 404 even if the local
             file exists
         visits: Dict of url, number of visits. If None, disable multi visit
@@ -80,10 +83,11 @@
     logger.debug('get_response_cb(%s, %s)', request, context)
     logger.debug('url: %s', request.url)
     logger.debug('ignore_urls: %s', ignore_urls)
-    if request.url in ignore_urls:
+    unquoted_url = unquote(request.url)
+    if unquoted_url in ignore_urls:
         context.status_code = 404
         return None
-    url = urlparse(request.url)
+    url = urlparse(unquoted_url)
     # http://pypi.org ~> http_pypi.org
     # https://files.pythonhosted.org ~> https_files.pythonhosted.org
     dirname = '%s_%s' % (url.scheme, url.hostname)
diff --git a/swh/core/tests/data/https_forge.s.o/api_diffusion,attachments[uris]=1 b/swh/core/tests/data/https_forge.s.o/api_diffusion,attachments[uris]=1
new file mode 100644
--- /dev/null
+++ b/swh/core/tests/data/https_forge.s.o/api_diffusion,attachments[uris]=1
@@ -0,0 +1 @@
+"something"
diff --git a/swh/core/tests/data/https_www.reference.com/web,q=What+Is+an+Example+of+a+URL?,qo=contentPageRelatedSearch,o=600605,l=dir,sga=1 b/swh/core/tests/data/https_www.reference.com/web,q=What+Is+an+Example+of+a+URL?,qo=contentPageRelatedSearch,o=600605,l=dir,sga=1
new file mode 100644
--- /dev/null
+++ b/swh/core/tests/data/https_www.reference.com/web,q=What+Is+an+Example+of+a+URL?,qo=contentPageRelatedSearch,o=600605,l=dir,sga=1
@@ -0,0 +1 @@
+"something else"
diff --git a/swh/core/tests/test_pytest_plugin.py b/swh/core/tests/test_pytest_plugin.py
--- a/swh/core/tests/test_pytest_plugin.py
+++ b/swh/core/tests/test_pytest_plugin.py
@@ -6,10 +6,25 @@
 import requests
 
 from os import path
+from urllib.parse import unquote
 
 from swh.core.pytest_plugin import requests_mock_datadir_factory
 
 
+def test_get_response_cb_with_encoded_url(requests_mock_datadir):
+    # The following urls (quoted, unquoted) will be resolved as the same file
+    for encoded_url, expected_response in [
+            ('https://forge.s.o/api/diffusion?attachments%5Buris%5D=1',
+             "something"),
+            ('https://www.reference.com/web?q=What+Is+an+Example+of+a+URL?&qo=contentPageRelatedSearch&o=600605&l=dir&sga=1',  # noqa
+             "something else"),
+    ]:
+        for url in [encoded_url, unquote(encoded_url)]:
+            response = requests.get(url)
+            assert response.ok
+            assert response.json() == expected_response
+
+
 def test_get_response_cb_with_visits_nominal(requests_mock_datadir_visits):
     response = requests.get('https://example.com/file.json')
     assert response.ok