diff --git a/tests/conftest.py b/tests/conftest.py
index 828a3991..158a443b 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -1,3 +1,9 @@
+import json
+import os
+import sys
+from pathlib import Path
+from uuid import uuid4
+
 import pytest
 
 import substra
@@ -7,6 +13,10 @@
 from .fl_interface import FLFunctionInputs
 from .fl_interface import FLFunctionOutputs
 from .fl_interface import FunctionCategory
+from substra.tools.task_resources import TaskResources
+from substra.tools.utils import import_module
+from substra.tools.workspace import FunctionWorkspace
+from tests.tools.utils import OutputIdentifiers
 
 
 def pytest_configure(config):
@@ -131,3 +141,69 @@ def asset_factory():
 @pytest.fixture()
 def data_sample(asset_factory):
     return asset_factory.create_data_sample()
+
+
+@pytest.fixture(autouse=True)
+def patch_cwd(monkeypatch, workdir):
+    # this is needed to ensure the workspace is located in a tmpdir
+    def getcwd():
+        return str(workdir)
+
+    monkeypatch.setattr(os, "getcwd", getcwd)
+
+
+@pytest.fixture()
+def valid_opener_code():
+    return """
+import json
+from substratools import Opener
+
+class FakeOpener(Opener):
+    def get_data(self, folder):
+        return 'X', list(range(0, 3))
+
+    def fake_data(self, n_samples):
+        return ['Xfake'] * n_samples, [0] * n_samples
+"""
+
+
+@pytest.fixture()
+def valid_opener(valid_opener_code):
+    import_module("opener", valid_opener_code)
+    yield
+    del sys.modules["opener"]
+
+
+@pytest.fixture()
+def valid_opener_script(workdir, valid_opener_code):
+    opener_path = workdir / "my_opener.py"
+    opener_path.write_text(valid_opener_code)
+
+    return str(opener_path)
+
+
+@pytest.fixture(autouse=True)
+def output_model_path(workdir: Path) -> str:
+    path = workdir / str(uuid4())
+    yield path
+    if path.exists():
+        os.remove(path)
+
+
+@pytest.fixture(autouse=True)
+def output_model_path_2(workdir: Path) -> str:
+    path = workdir / str(uuid4())
+    yield path
+    if path.exists():
+        os.remove(path)
+
+
+@pytest.fixture()
+def valid_function_workspace(output_model_path: str) -> FunctionWorkspace:
+    workspace_outputs = TaskResources(
+        json.dumps([{"id": OutputIdentifiers.shared, "value": str(output_model_path), "multiple": False}])
+    )
+
+    workspace = FunctionWorkspace(outputs=workspace_outputs)
+
+    return workspace
diff --git a/tests/tools/test_aggregatealgo.py b/tests/tools/test_aggregatealgo.py
index 9b814db3..a6117cd9 100644
--- a/tests/tools/test_aggregatealgo.py
+++ b/tests/tools/test_aggregatealgo.py
@@ -13,8 +13,8 @@
 from substratools.task_resources import TaskResources
 from substratools.workspace import FunctionWorkspace
 from tests.tools import utils
-from tests.utils import InputIdentifiers
-from tests.utils import OutputIdentifiers
+from tests.tools.utils import InputIdentifiers
+from tests.tools.utils import OutputIdentifiers
 
 
 @pytest.fixture(autouse=True)
diff --git a/tests/tools/test_compositealgo.py b/tests/tools/test_compositealgo.py
index 89beb6d9..a8f9aaf6 100644
--- a/tests/tools/test_compositealgo.py
+++ b/tests/tools/test_compositealgo.py
@@ -12,8 +12,8 @@
 from substratools.task_resources import TaskResources
 from substratools.workspace import FunctionWorkspace
 from tests.tools import utils
-from tests.utils import InputIdentifiers
-from tests.utils import OutputIdentifiers
+from tests.tools.utils import InputIdentifiers
+from tests.tools.utils import OutputIdentifiers
 
 
 @pytest.fixture(autouse=True)
diff --git a/tests/tools/test_function.py b/tests/tools/test_function.py
index c76c6170..41c67db4 100644
--- a/tests/tools/test_function.py
+++ b/tests/tools/test_function.py
@@ -17,8 +17,8 @@
 from substratools.task_resources import TaskResources
 from substratools.workspace import FunctionWorkspace
 from tests.tools import utils
-from tests.utils import InputIdentifiers
-from tests.utils import OutputIdentifiers
+from tests.tools.utils import InputIdentifiers
+from tests.tools.utils import OutputIdentifiers
 
 
 @pytest.fixture(autouse=True)
diff --git a/tests/tools/test_metrics.py b/tests/tools/test_metrics.py
index c8d4944c..1018d37f 100644
--- a/tests/tools/test_metrics.py
+++ b/tests/tools/test_metrics.py
@@ -14,8 +14,8 @@
 from substratools.task_resources import TaskResources
 from substratools.workspace import FunctionWorkspace
 from tests.tools import utils
-from tests.utils import InputIdentifiers
-from tests.utils import OutputIdentifiers
+from tests.tools.utils import InputIdentifiers
+from tests.tools.utils import OutputIdentifiers
 
 
 @pytest.fixture()
diff --git a/tests/tools/test_workflow.py b/tests/tools/test_workflow.py
index 726439c5..fc924c51 100644
--- a/tests/tools/test_workflow.py
+++ b/tests/tools/test_workflow.py
@@ -11,8 +11,8 @@
 from substratools.utils import import_module
 from substratools.workspace import FunctionWorkspace
 from tests.tools import utils
-from tests.utils import InputIdentifiers
-from tests.utils import OutputIdentifiers
+from tests.tools.utils import InputIdentifiers
+from tests.tools.utils import OutputIdentifiers
 
 
 @pytest.fixture
diff --git a/tests/tools/tools_conftest.py b/tests/tools/tools_conftest.py
index a51e6fe9..c0b69f9b 100644
--- a/tests/tools/tools_conftest.py
+++ b/tests/tools/tools_conftest.py
@@ -9,7 +9,7 @@
 from substratools.task_resources import TaskResources
 from substratools.utils import import_module
 from substratools.workspace import FunctionWorkspace
-from tests.utils import OutputIdentifiers
+from tests.tools.utils import OutputIdentifiers
 
 
 @pytest.fixture