diff --git a/tests/__init__.py b/tests/__init__.py
new file mode 100644
index 000000000..dd2ca018c
--- /dev/null
+++ b/tests/__init__.py
@@ -0,0 +1,8 @@
+# -*- coding: utf-8 -*-
+#
+# Copyright (C) 2025 Graz University of Technology.
+#
+# Invenio App RDM is free software; you can redistribute it and/or modify it
+# under the terms of the MIT License; see LICENSE file for more details.
+
+"""Tests."""
diff --git a/tests/api/__init__.py b/tests/api/__init__.py
new file mode 100644
index 000000000..dd2ca018c
--- /dev/null
+++ b/tests/api/__init__.py
@@ -0,0 +1,8 @@
+# -*- coding: utf-8 -*-
+#
+# Copyright (C) 2025 Graz University of Technology.
+#
+# Invenio App RDM is free software; you can redistribute it and/or modify it
+# under the terms of the MIT License; see LICENSE file for more details.
+
+"""Tests."""
diff --git a/tests/fixtures/__init__.py b/tests/fixtures/__init__.py
new file mode 100644
index 000000000..dd2ca018c
--- /dev/null
+++ b/tests/fixtures/__init__.py
@@ -0,0 +1,8 @@
+# -*- coding: utf-8 -*-
+#
+# Copyright (C) 2025 Graz University of Technology.
+#
+# Invenio App RDM is free software; you can redistribute it and/or modify it
+# under the terms of the MIT License; see LICENSE file for more details.
+
+"""Tests."""
diff --git a/tests/redirector/__init__.py b/tests/redirector/__init__.py
new file mode 100644
index 000000000..dd2ca018c
--- /dev/null
+++ b/tests/redirector/__init__.py
@@ -0,0 +1,8 @@
+# -*- coding: utf-8 -*-
+#
+# Copyright (C) 2025 Graz University of Technology.
+#
+# Invenio App RDM is free software; you can redistribute it and/or modify it
+# under the terms of the MIT License; see LICENSE file for more details.
+
+"""Tests."""
diff --git a/tests/ui/__init__.py b/tests/ui/__init__.py
new file mode 100644
index 000000000..dd2ca018c
--- /dev/null
+++ b/tests/ui/__init__.py
@@ -0,0 +1,8 @@
+# -*- coding: utf-8 -*-
+#
+# Copyright (C) 2025 Graz University of Technology.
+#
+# Invenio App RDM is free software; you can redistribute it and/or modify it
+# under the terms of the MIT License; see LICENSE file for more details.
+
+"""Tests."""