diff --git a/pyproject.toml b/pyproject.toml
index cde86d39..d7827280 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -29,12 +29,20 @@ requires-python = ">=3.11"
 # IMPORTANT:
 # Run 'tox -e deps' after making changes here. This will update requirement files.
 # Make sure to list one dependency per line.
-dependencies = ["plopp", "scipp", "scipy", "lazy-loader"]
+dependencies = [
+  "plopp>=23.10.0",
+  "scipp>=24.11.0",
+  "scipy>=1.12.0",
+  "lazy-loader>=0.3",
+]
 
 dynamic = ["version"]
 
 [project.optional-dependencies]
-test = ["pytest", "scippneutron"]
+test = [
+  "pytest>=8.0",
+  "scippneutron>=24.12.0",
+]
 
 [project.urls]
 "Bug Tracker" = "https://github.com/scipp/tof/issues"
diff --git a/tests/__init__.py b/tests/__init__.py
deleted file mode 100644
index df176980..00000000
--- a/tests/__init__.py
+++ /dev/null
@@ -1,2 +0,0 @@
-# SPDX-License-Identifier: BSD-3-Clause
-# Copyright (c) 2023 Scipp contributors (https://github.com/scipp)
diff --git a/tests/common.py b/tests/common.py
deleted file mode 100644
index b4e910a8..00000000
--- a/tests/common.py
+++ /dev/null
@@ -1,73 +0,0 @@
-# SPDX-License-Identifier: BSD-3-Clause
-# Copyright (c) 2023 Scipp contributors (https://github.com/scipp)
-
-import numpy as np
-import scipp as sc
-
-import tof
-
-Hz = sc.Unit('Hz')
-deg = sc.Unit('deg')
-meter = sc.Unit('m')
-ms = sc.Unit('ms')
-two_pi = 2.0 * np.pi * sc.units.rad
-
-
-def make_chopper(topen, tclose, f, phase, distance, name):
-    aopen = two_pi * sc.concat(topen, dim='cutout').to(unit='s') * f
-    aclose = two_pi * sc.concat(tclose, dim='cutout').to(unit='s') * f
-    return tof.Chopper(
-        frequency=f,
-        open=aopen,
-        close=aclose,
-        phase=phase,
-        distance=distance,
-        name=name,
-    )
-
-
-def make_source(arrival_times, distance, pulses=1, frequency=None):
-    # Arrival times are distance * m_over_h * wavelength
-    return tof.Source.from_neutrons(
-        birth_times=sc.array(
-            dims=['event'],
-            values=[0.0] * len(arrival_times),
-            unit='s',
-        ),
-        wavelengths=arrival_times.to(unit='s') / (distance * tof.utils.m_over_h),
-        pulses=pulses,
-        frequency=frequency,
-    )
-
-
-def dummy_chopper():
-    return tof.Chopper(
-        frequency=1.0 * Hz,
-        open=sc.array(dims=['cutout'], values=[0.0], unit='deg'),
-        close=sc.array(dims=['cutout'], values=[1.0], unit='deg'),
-        phase=0.0 * deg,
-        distance=1.0 * meter,
-        name='dummy_chopper',
-    )
-
-
-def dummy_detector():
-    return tof.Detector(
-        distance=1.0 * meter,
-        name='dummy_detector',
-    )
-
-
-def dummy_source():
-    return tof.Source.from_neutrons(
-        birth_times=sc.array(
-            dims=['event'],
-            values=[0.0],
-            unit='s',
-        ),
-        wavelengths=sc.array(
-            dims=['event'],
-            values=[1.0],
-            unit='angstrom',
-        ),
-    )
diff --git a/tests/conftest.py b/tests/conftest.py
new file mode 100644
index 00000000..fd6d061c
--- /dev/null
+++ b/tests/conftest.py
@@ -0,0 +1,70 @@
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright (c) 2025 Scipp contributors (https://github.com/scipp)
+
+import numpy as np
+import pytest
+import scipp as sc
+
+import tof
+
+
+@pytest.fixture
+def make_chopper():
+    def _make_chopper(topen, tclose, f, phase, distance, name):
+        two_pi = 2.0 * np.pi * sc.units.rad
+        aopen = two_pi * sc.concat(topen, dim='cutout').to(unit='s') * f
+        aclose = two_pi * sc.concat(tclose, dim='cutout').to(unit='s') * f
+        return tof.Chopper(
+            frequency=f,
+            open=aopen,
+            close=aclose,
+            phase=phase,
+            distance=distance,
+            name=name,
+        )
+
+    return _make_chopper
+
+
+@pytest.fixture
+def make_source():
+    def _make_source(arrival_times, distance, pulses=1, frequency=None):
+        # Arrival times are distance * m_over_h * wavelength
+        return tof.Source.from_neutrons(
+            birth_times=sc.array(
+                dims=['event'], values=[0.0] * len(arrival_times), unit='s'
+            ),
+            wavelengths=arrival_times.to(unit='s') / (distance * tof.utils.m_over_h),
+            pulses=pulses,
+            frequency=frequency,
+        )
+
+    return _make_source
+
+
+@pytest.fixture
+def dummy_chopper():
+    return tof.Chopper(
+        frequency=sc.scalar(1.0, unit="Hz"),
+        open=sc.array(dims=['cutout'], values=[0.0], unit='deg'),
+        close=sc.array(dims=['cutout'], values=[1.0], unit='deg'),
+        phase=sc.scalar(0.0, unit="deg"),
+        distance=sc.scalar(1.0, unit="m"),
+        name='dummy_chopper',
+    )
+
+
+@pytest.fixture
+def dummy_detector():
+    return tof.Detector(
+        distance=sc.scalar(1.0, unit="m"),
+        name='dummy_detector',
+    )
+
+
+@pytest.fixture
+def dummy_source():
+    return tof.Source.from_neutrons(
+        birth_times=sc.array(dims=['event'], values=[0.0], unit='s'),
+        wavelengths=sc.array(dims=['event'], values=[1.0], unit='angstrom'),
+    )
diff --git a/tests/model_test.py b/tests/model_test.py
index 34935a5f..70a3a8df 100644
--- a/tests/model_test.py
+++ b/tests/model_test.py
@@ -11,21 +11,13 @@
 
 import tof
 
-from .common import (
-    dummy_chopper,
-    dummy_detector,
-    dummy_source,
-    make_chopper,
-    make_source,
-)
-
 Hz = sc.Unit('Hz')
 deg = sc.Unit('deg')
 meter = sc.Unit('m')
 ms = sc.Unit('ms')
 
 
-def test_one_chopper_one_opening():
+def test_one_chopper_one_opening(make_chopper, make_source):
     # Make a chopper open from 10-20 ms. Assume zero phase.
     topen = 10.0 * ms
     tclose = 20.0 * ms
@@ -79,7 +71,7 @@ def test_one_chopper_one_opening():
     )
 
 
-def test_two_choppers_one_opening():
+def test_two_choppers_one_opening(make_chopper, make_source):
     # Make a first chopper open from 5-16 ms. Assume zero phase.
     topen = 5.0 * ms
     tclose = 16.0 * ms
@@ -166,7 +158,7 @@ def test_two_choppers_one_opening():
     )
 
 
-def test_two_choppers_one_and_two_openings():
+def test_two_choppers_one_and_two_openings(make_chopper, make_source):
     topen = 5.0 * ms
     tclose = 16.0 * ms
     chopper1 = make_chopper(
@@ -224,7 +216,7 @@ def test_two_choppers_one_and_two_openings():
     )
 
 
-def test_neutron_conservation():
+def test_neutron_conservation(make_chopper):
     N = 100_000
     source = tof.Source(facility='ess', neutrons=N)
 
@@ -266,20 +258,22 @@ def test_neutron_conservation():
     assert det.sum().value + det.masks['blocked_by_others'].sum().value == N
 
 
-def test_add_chopper_and_detector():
-    chopper = dummy_chopper()
-    detector = dummy_detector()
-    model = tof.Model(source=dummy_source())
+def test_add_chopper_and_detector(dummy_chopper, dummy_detector, dummy_source):
+    chopper = dummy_chopper
+    detector = dummy_detector
+    model = tof.Model(source=dummy_source)
     model.add(chopper)
     assert 'dummy_chopper' in model.choppers
     model.add(detector)
     assert 'dummy_detector' in model.detectors
 
 
-def test_add_components_with_same_name_raises():
-    chopper = dummy_chopper()
-    detector = dummy_detector()
-    model = tof.Model(source=dummy_source())
+def test_add_components_with_same_name_raises(
+    dummy_chopper, dummy_detector, dummy_source
+):
+    chopper = dummy_chopper
+    detector = dummy_detector
+    model = tof.Model(source=dummy_source)
     model.add(chopper)
     with pytest.raises(
         KeyError, match='Component with name dummy_chopper already exists'
@@ -297,33 +291,35 @@ def test_add_components_with_same_name_raises():
         model.add(detector2)
 
 
-def test_create_model_with_duplicate_component_names_raises():
-    chopper = dummy_chopper()
-    detector = dummy_detector()
+def test_create_model_with_duplicate_component_names_raises(
+    dummy_chopper, dummy_detector, dummy_source
+):
+    chopper = dummy_chopper
+    detector = dummy_detector
     with pytest.raises(
         ValueError, match="More than one component named 'dummy_chopper' found"
     ):
-        tof.Model(source=dummy_source(), choppers=[chopper, chopper])
+        tof.Model(source=dummy_source, choppers=[chopper, chopper])
     with pytest.raises(
         ValueError, match="More than one component named 'dummy_detector' found"
     ):
-        tof.Model(source=dummy_source(), detectors=[detector, detector])
+        tof.Model(source=dummy_source, detectors=[detector, detector])
 
 
-def test_iter():
-    chopper = dummy_chopper()
-    detector = dummy_detector()
-    model = tof.Model(source=dummy_source())
+def test_iter(dummy_chopper, dummy_detector, dummy_source):
+    chopper = dummy_chopper
+    detector = dummy_detector
+    model = tof.Model(source=dummy_source)
     model.add(chopper)
     assert 'dummy_chopper' in model.choppers
     model.add(detector)
     assert 'dummy_detector' in model.detectors
 
 
-def test_remove():
-    chopper = dummy_chopper()
-    detector = dummy_detector()
-    model = tof.Model(source=dummy_source(), choppers=[chopper], detectors=[detector])
+def test_remove(dummy_chopper, dummy_detector, dummy_source):
+    chopper = dummy_chopper
+    detector = dummy_detector
+    model = tof.Model(source=dummy_source, choppers=[chopper], detectors=[detector])
     del model['dummy_chopper']
     assert 'dummy_chopper' not in model
     assert 'dummy_detector' in model
@@ -331,42 +327,42 @@ def test_remove():
     assert 'dummy_detector' not in model
 
 
-def test_getitem():
-    chopper = dummy_chopper()
-    detector = dummy_detector()
-    model = tof.Model(source=dummy_source(), choppers=[chopper], detectors=[detector])
+def test_getitem(dummy_chopper, dummy_detector, dummy_source):
+    chopper = dummy_chopper
+    detector = dummy_detector
+    model = tof.Model(source=dummy_source, choppers=[chopper], detectors=[detector])
     assert model['dummy_chopper'] is chopper
     assert model['dummy_detector'] is detector
     with pytest.raises(KeyError, match='No component with name foo'):
         model['foo']
 
 
-def test_input_can_be_single_component():
-    chopper = dummy_chopper()
-    detector = dummy_detector()
-    model = tof.Model(source=dummy_source(), choppers=chopper, detectors=detector)
+def test_input_can_be_single_component(dummy_chopper, dummy_detector, dummy_source):
+    chopper = dummy_chopper
+    detector = dummy_detector
+    model = tof.Model(source=dummy_source, choppers=chopper, detectors=detector)
     assert 'dummy_chopper' in model.choppers
     assert 'dummy_detector' in model.detectors
 
 
-def test_bad_input_type_raises():
-    chopper = dummy_chopper()
-    detector = dummy_detector()
+def test_bad_input_type_raises(dummy_chopper, dummy_detector, dummy_source):
+    chopper = dummy_chopper
+    detector = dummy_detector
     with pytest.raises(TypeError, match='Invalid input type'):
-        _ = tof.Model(source=dummy_source(), choppers='bad chopper')
+        _ = tof.Model(source=dummy_source, choppers='bad chopper')
     with pytest.raises(TypeError, match='Invalid input type'):
-        _ = tof.Model(source=dummy_source(), choppers=[chopper], detectors='abc')
+        _ = tof.Model(source=dummy_source, choppers=[chopper], detectors='abc')
     with pytest.raises(TypeError, match='Invalid input type'):
-        _ = tof.Model(source=dummy_source(), choppers=[chopper, 'bad chopper'])
+        _ = tof.Model(source=dummy_source, choppers=[chopper, 'bad chopper'])
     with pytest.raises(TypeError, match='Invalid input type'):
-        _ = tof.Model(source=dummy_source(), detectors=(1234, detector))
+        _ = tof.Model(source=dummy_source, detectors=(1234, detector))
     with pytest.raises(TypeError, match='Invalid input type'):
-        _ = tof.Model(source=dummy_source(), choppers=[detector])
+        _ = tof.Model(source=dummy_source, choppers=[detector])
     with pytest.raises(TypeError, match='Invalid input type'):
-        _ = tof.Model(source=dummy_source(), detectors=[chopper])
+        _ = tof.Model(source=dummy_source, detectors=[chopper])
 
 
-def test_model_repr_does_not_raise():
+def test_model_repr_does_not_raise(make_chopper, make_source):
     N = 10_000
     source = tof.Source(facility='ess', neutrons=N)
     chopper1 = make_chopper(
@@ -392,7 +388,7 @@ def test_model_repr_does_not_raise():
     assert repr(model) is not None
 
 
-def test_component_distance():
+def test_component_distance(make_chopper, make_source):
     # Make a chopper open from 10-20 ms. Assume zero phase.
     topen = 10.0 * ms
     tclose = 20.0 * ms
diff --git a/tests/result_test.py b/tests/result_test.py
index c8dc0bd3..f72872ab 100644
--- a/tests/result_test.py
+++ b/tests/result_test.py
@@ -8,8 +8,6 @@
 
 import tof
 
-from .common import make_chopper, make_source
-
 Hz = sc.Unit('Hz')
 deg = sc.Unit('deg')
 meter = sc.Unit('m')
@@ -19,7 +17,7 @@
 
 
 @pytest.fixture
-def chopper():
+def chopper(make_chopper):
     return make_chopper(
         topen=[topen],
         tclose=[tclose],
@@ -36,7 +34,7 @@ def detector():
 
 
 @pytest.fixture
-def source(chopper):
+def source(chopper, make_source):
     return make_source(
         arrival_times=sc.concat(
             [0.9 * topen, 0.5 * (topen + tclose), 1.1 * tclose], dim='event'
@@ -46,7 +44,7 @@ def source(chopper):
 
 
 @pytest.fixture
-def multi_pulse_source(chopper):
+def multi_pulse_source(chopper, make_source):
     return make_source(
         arrival_times=sc.concat(
             [0.9 * topen, 0.5 * (topen + tclose), 1.1 * tclose], dim='event'