diff --git a/lib/iris/tests/unit/common/mixin/test__get_valid_standard_name.py b/lib/iris/tests/unit/common/mixin/test__get_valid_standard_name.py
index 67ba108333..c7be9d48ca 100644
--- a/lib/iris/tests/unit/common/mixin/test__get_valid_standard_name.py
+++ b/lib/iris/tests/unit/common/mixin/test__get_valid_standard_name.py
@@ -4,65 +4,60 @@
 # See LICENSE in the root of the repository for full licensing details.
 """Unit tests for the :func:`iris.common.mixin._get_valid_standard_name`."""
 
-# Import iris.tests first so that some things can be initialised before
-# importing anything else.
-import iris.tests as tests  # isort:skip
+import pytest
 
 from iris.common.mixin import _get_valid_standard_name
 
 
-class Test(tests.IrisTest):
-    def setUp(self):
+class Test:
+    @pytest.fixture(autouse=True)
+    def _setup(self):
         self.emsg = "'{}' is not a valid standard_name"
 
     def test_pass_thru_none(self):
         name = None
-        self.assertEqual(_get_valid_standard_name(name), name)
+        assert _get_valid_standard_name(name) == name
 
     def test_pass_thru_empty(self):
         name = ""
-        self.assertEqual(_get_valid_standard_name(name), name)
+        assert _get_valid_standard_name(name) == name
 
     def test_pass_thru_whitespace(self):
         name = "       "
-        self.assertEqual(_get_valid_standard_name(name), name)
+        assert _get_valid_standard_name(name) == name
 
     def test_valid_standard_name(self):
         name = "air_temperature"
-        self.assertEqual(_get_valid_standard_name(name), name)
+        assert _get_valid_standard_name(name) == name
 
     def test_standard_name_alias(self):
         name = "atmosphere_optical_thickness_due_to_pm1_ambient_aerosol"
-        self.assertEqual(_get_valid_standard_name(name), name)
+        assert _get_valid_standard_name(name) == name
 
     def test_invalid_standard_name(self):
         name = "not_a_standard_name"
-        with self.assertRaisesRegex(ValueError, self.emsg.format(name)):
+        with pytest.raises(ValueError, match=self.emsg.format(name)):
             _get_valid_standard_name(name)
 
     def test_valid_standard_name_valid_modifier(self):
         name = "air_temperature standard_error"
-        self.assertEqual(_get_valid_standard_name(name), name)
+        assert _get_valid_standard_name(name) == name
 
     def test_valid_standard_name_valid_modifier_extra_spaces(self):
         name = "air_temperature      standard_error"
-        self.assertEqual(_get_valid_standard_name(name), name)
+        assert _get_valid_standard_name(name) == name
 
     def test_invalid_standard_name_valid_modifier(self):
         name = "not_a_standard_name standard_error"
-        with self.assertRaisesRegex(ValueError, self.emsg.format(name)):
+        with pytest.raises(ValueError, match=self.emsg.format(name)):
             _get_valid_standard_name(name)
 
     def test_valid_standard_invalid_name_modifier(self):
         name = "air_temperature extra_names standard_error"
-        with self.assertRaisesRegex(ValueError, self.emsg.format(name)):
+        with pytest.raises(ValueError, match=self.emsg.format(name)):
             _get_valid_standard_name(name)
 
     def test_valid_standard_valid_name_modifier_extra_names(self):
         name = "air_temperature standard_error extra words"
-        with self.assertRaisesRegex(ValueError, self.emsg.format(name)):
+        with pytest.raises(ValueError, match=self.emsg.format(name)):
             _get_valid_standard_name(name)
-
-
-if __name__ == "__main__":
-    tests.main()