diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 7bd69b26fa..7c93c268b6 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -131,6 +131,7 @@ jobs:
         run: |
           pip install pytest
           pip install pytest-xvfb
+          pip install pytest-mock
 
       - name: Install silx package
         run: pip install --pre --find-links dist/ silx
diff --git a/ci/appveyor.yml b/ci/appveyor.yml
index 18b83915f1..21b99dccb4 100644
--- a/ci/appveyor.yml
+++ b/ci/appveyor.yml
@@ -100,6 +100,7 @@ before_test:
     # Install pytest
     - "pip install %PIP_OPTIONS% pytest"
     - "pip install %PIP_OPTIONS% pytest-xvfb"
+    - "pip install %PIP_OPTIONS% pytest-mock"
 
     # Install the generated wheel package to test it
     # Make sure silx does not come from cache or pypi
diff --git a/requirements-dev.txt b/requirements-dev.txt
index 9b5807a65d..604943eaf5 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -13,6 +13,7 @@ pandoc            # For documentation Qt snapshot updates
 pytest            # For testing
 pytest-xvfb       # For GUI testing
 pytest-cov        # For coverage
+pytest-mock
 
 hdf5plugin        # For HDF5 compression filters handling
 
diff --git a/setup.py b/setup.py
index d03f4913cb..50a67c47bd 100644
--- a/setup.py
+++ b/setup.py
@@ -523,6 +523,7 @@ def get_project_configuration():
     test_requires = [
         "pytest",
         "pytest-xvfb",
+        "pytest-mock",
         'bitshuffle'
     ]