diff --git a/lib/iris/tests/unit/concatenate/test__CubeSignature.py b/lib/iris/tests/unit/concatenate/test__CubeSignature.py
index a148b6fdbd..a55140f156 100644
--- a/lib/iris/tests/unit/concatenate/test__CubeSignature.py
+++ b/lib/iris/tests/unit/concatenate/test__CubeSignature.py
@@ -6,10 +6,11 @@
 
 # import iris tests first so that some things can be initialised
 # before importing anything else.
-import iris.tests as tests  # isort:skip
+from dataclasses import dataclass
 
 from cf_units import Unit
 import numpy as np
+import pytest
 
 from iris._concatenate import _CubeSignature as CubeSignature
 from iris.coords import DimCoord
@@ -17,65 +18,73 @@
 from iris.util import new_axis
 
 
-class Test__coordinate_dim_metadata_equality(tests.IrisTest):
-    def setUp(self):
+class Test__coordinate_dim_metadata_equality:
+    @pytest.fixture
+    def sample_data(self):
+        # Return a standard set of test items, wrapped in a data object
+        @dataclass
+        class SampleData:
+            series_inc: CubeSignature = None
+            series_inc_cube: Cube = None
+            series_dec: CubeSignature = None
+            series_dec_cube: Cube = None
+            scalar_cube: Cube = None
+
+        data = SampleData()
+
         nt = 10
-        data = np.arange(nt, dtype=np.float32)
-        cube = Cube(data, standard_name="air_temperature", units="K")
+        cube_data = np.arange(nt, dtype=np.float32)
+        cube = Cube(cube_data, standard_name="air_temperature", units="K")
         # Temporal coordinate.
         t_units = Unit("hours since 1970-01-01 00:00:00", calendar="standard")
         t_coord = DimCoord(points=np.arange(nt), standard_name="time", units=t_units)
         cube.add_dim_coord(t_coord, 0)
-
         # Increasing 1D time-series cube.
-        self.series_inc_cube = cube
-        self.series_inc = CubeSignature(self.series_inc_cube)
+        data.series_inc_cube = cube
+        data.series_inc = CubeSignature(data.series_inc_cube)
 
         # Decreasing 1D time-series cube.
-        self.series_dec_cube = self.series_inc_cube.copy()
-        self.series_dec_cube.remove_coord("time")
+        data.series_dec_cube = data.series_inc_cube.copy()
+        data.series_dec_cube.remove_coord("time")
         t_tmp = DimCoord(
             points=t_coord.points[::-1], standard_name="time", units=t_units
         )
-        self.series_dec_cube.add_dim_coord(t_tmp, 0)
-        self.series_dec = CubeSignature(self.series_dec_cube)
+        data.series_dec_cube.add_dim_coord(t_tmp, 0)
+        data.series_dec = CubeSignature(data.series_dec_cube)
 
         # Scalar 0D time-series cube with scalar time coordinate.
         cube = Cube(0, standard_name="air_temperature", units="K")
         cube.add_aux_coord(DimCoord(points=nt, standard_name="time", units=t_units))
-        self.scalar_cube = cube
+        data.scalar_cube = cube
+        return data
 
-    def test_scalar_non_common_axis(self):
-        scalar = CubeSignature(self.scalar_cube)
-        self.assertNotEqual(self.series_inc.dim_metadata, scalar.dim_metadata)
-        self.assertNotEqual(self.series_dec.dim_metadata, scalar.dim_metadata)
+    def test_scalar_non_common_axis(self, sample_data):
+        scalar = CubeSignature(sample_data.scalar_cube)
+        assert sample_data.series_inc.dim_metadata != scalar.dim_metadata
+        assert sample_data.series_dec.dim_metadata != scalar.dim_metadata
 
-    def test_1d_single_value_common_axis(self):
+    def test_1d_single_value_common_axis(self, sample_data):
         # Manually promote scalar time cube to be a 1d cube.
-        single = CubeSignature(new_axis(self.scalar_cube, "time"))
-        self.assertEqual(self.series_inc.dim_metadata, single.dim_metadata)
-        self.assertEqual(self.series_dec.dim_metadata, single.dim_metadata)
+        single = CubeSignature(new_axis(sample_data.scalar_cube, "time"))
+        assert sample_data.series_inc.dim_metadata == single.dim_metadata
+        assert sample_data.series_dec.dim_metadata == single.dim_metadata
 
-    def test_increasing_common_axis(self):
-        series_inc = self.series_inc
-        series_dec = self.series_dec
-        self.assertEqual(series_inc.dim_metadata, series_inc.dim_metadata)
-        self.assertNotEqual(series_inc.dim_metadata, series_dec.dim_metadata)
+    def test_increasing_common_axis(self, sample_data):
+        series_inc = sample_data.series_inc
+        series_dec = sample_data.series_dec
+        assert series_inc.dim_metadata == series_inc.dim_metadata
+        assert series_inc.dim_metadata != series_dec.dim_metadata
 
-    def test_decreasing_common_axis(self):
-        series_inc = self.series_inc
-        series_dec = self.series_dec
-        self.assertNotEqual(series_dec.dim_metadata, series_inc.dim_metadata)
-        self.assertEqual(series_dec.dim_metadata, series_dec.dim_metadata)
+    def test_decreasing_common_axis(self, sample_data):
+        series_inc = sample_data.series_inc
+        series_dec = sample_data.series_dec
+        assert series_dec.dim_metadata != series_inc.dim_metadata
+        assert series_dec.dim_metadata == series_dec.dim_metadata
 
-    def test_circular(self):
-        series_inc = self.series_inc
-        circular_cube = self.series_inc_cube.copy()
+    def test_circular(self, sample_data):
+        series_inc = sample_data.series_inc
+        circular_cube = sample_data.series_inc_cube.copy()
         circular_cube.coord("time").circular = True
         circular = CubeSignature(circular_cube)
-        self.assertNotEqual(circular.dim_metadata, series_inc.dim_metadata)
-        self.assertEqual(circular.dim_metadata, circular.dim_metadata)
-
-
-if __name__ == "__main__":
-    tests.main()
+        assert circular.dim_metadata != series_inc.dim_metadata
+        assert circular.dim_metadata == circular.dim_metadata