diff --git a/swh/scanner/tests/conftest.py b/swh/scanner/tests/conftest.py
index 8f8e709..4430257 100644
--- a/swh/scanner/tests/conftest.py
+++ b/swh/scanner/tests/conftest.py
@@ -1,158 +1,158 @@
 # Copyright (C) 2020  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 asyncio
 import os
 from pathlib import Path
 import shutil
 
 import aiohttp
 from aioresponses import aioresponses  # type: ignore
 import pytest
 
 from swh.model.cli import swhid_of_dir, swhid_of_file
 from swh.scanner.model import Tree
 
 from .data import present_swhids
 from .flask_api import create_app
 
 
 @pytest.fixture
 def mock_aioresponse():
     with aioresponses() as m:
         yield m
 
 
 @pytest.fixture
 def event_loop():
     """Fixture that generate an asyncio event loop."""
     loop = asyncio.new_event_loop()
     asyncio.set_event_loop(loop)
     yield loop
     loop.close()
 
 
 @pytest.fixture
 async def aiosession():
     """Fixture that generate an aiohttp Client Session."""
     session = aiohttp.ClientSession()
     yield session
     session.detach()
 
 
 @pytest.fixture(scope="function")
 def temp_folder(tmp_path):
     """Fixture that generates a temporary folder with the following
     structure:
 
     .. code-block:: python
 
         root = {
             subdir: {
                 subsubdir
                 filesample.txt
                 filesample2.txt
             }
             subdir2
             subfile.txt
         }
     """
     root = tmp_path
     subdir = root / "subdir"
     subdir.mkdir()
     subsubdir = subdir / "subsubdir"
     subsubdir.mkdir()
     subdir2 = root / "subdir2"
     subdir2.mkdir()
     subfile = root / "subfile.txt"
     subfile.touch()
     filesample = subdir / "filesample.txt"
     filesample.touch()
     filesample2 = subdir / "filesample2.txt"
     filesample2.touch()
 
     avail_path = {
-        subdir: swhid_of_dir(bytes(subdir)),
-        subsubdir: swhid_of_dir(bytes(subsubdir)),
-        subdir2: swhid_of_dir(bytes(subdir2)),
-        subfile: swhid_of_file(bytes(subfile)),
-        filesample: swhid_of_file(bytes(filesample)),
-        filesample2: swhid_of_file(bytes(filesample2)),
+        subdir: str(swhid_of_dir(bytes(subdir))),
+        subsubdir: str(swhid_of_dir(bytes(subsubdir))),
+        subdir2: str(swhid_of_dir(bytes(subdir2))),
+        subfile: str(swhid_of_file(bytes(subfile))),
+        filesample: str(swhid_of_file(bytes(filesample))),
+        filesample2: str(swhid_of_file(bytes(filesample2))),
     }
 
     return {
         "root": root,
         "paths": avail_path,
         "filesample": filesample,
         "filesample2": filesample2,
         "subsubdir": subsubdir,
         "subdir": subdir,
     }
 
 
 @pytest.fixture(scope="function")
 def example_tree(temp_folder):
     """Fixture that generate a Tree with the root present in the
        session fixture "temp_folder".
     """
     example_tree = Tree(temp_folder["root"])
     assert example_tree.path == temp_folder["root"]
 
     return example_tree
 
 
 @pytest.fixture(scope="function")
 def example_dirs(example_tree, temp_folder):
     """
         Fixture that fill the fixture example_tree with the values contained in
         the fixture temp_folder and returns the directories information of the
         filled example_tree.
 
     """
     root = temp_folder["root"]
     filesample_path = temp_folder["filesample"]
     filesample2_path = temp_folder["filesample2"]
     subsubdir_path = temp_folder["subsubdir"]
     known_paths = [filesample_path, filesample2_path, subsubdir_path]
 
     for path, swhid in temp_folder["paths"].items():
         if path in known_paths:
             example_tree.add_node(path, swhid, True)
         else:
             example_tree.add_node(path, swhid, False)
 
     return example_tree.get_directories_info(root)
 
 
 @pytest.fixture
 def test_sample_folder(datadir, tmp_path):
     """Location of the "data" folder """
     archive_path = Path(os.path.join(datadir, "sample-folder.tgz"))
     assert archive_path.exists()
     shutil.unpack_archive(archive_path, extract_dir=tmp_path)
     test_sample_folder = Path(os.path.join(tmp_path, "sample-folder"))
     assert test_sample_folder.exists()
     return test_sample_folder
 
 
 @pytest.fixture
 def test_swhids_sample(tmp_path):
     """Create and return the opened "swhids_sample" file,
        filled with present swhids present in data.py
     """
     test_swhids_sample = Path(os.path.join(tmp_path, "swhids_sample.txt"))
 
     with open(test_swhids_sample, "w") as f:
         f.write("\n".join(swhid for swhid in present_swhids))
 
     assert test_swhids_sample.exists()
     return open(test_swhids_sample, "r")
 
 
 @pytest.fixture(scope="session")
 def app():
     """Flask backend API (used by live_server)."""
     app = create_app()
     return app