diff --git a/tests/conftest.py b/tests/conftest.py
index d272b8d7..2bcb36d0 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -127,9 +127,7 @@ def platform_td_big(request):
         yield platform
 
 
-db_platform_big = pytest.fixture(
-    platform_td_big, scope="session", name="db_platform_big"
-)
+db_platform_big = pytest.fixture(platform_td_big, scope="class", name="db_platform_big")
 
 
 def pytest_generate_tests(metafunc):
diff --git a/tests/data/test_count.py b/tests/data/test_count.py
index 78bce8f7..e23b20b5 100644
--- a/tests/data/test_count.py
+++ b/tests/data/test_count.py
@@ -4,81 +4,77 @@
 
 import ixmp4
 
-from ..fixtures import BigIamcDataset
-
 
 def deepgetattr(obj, attr):
     return reduce(getattr, attr.split("."), obj)
 
 
-big = BigIamcDataset()
-
-
-@pytest.mark.parametrize(
-    "repo_name,filters",
-    [
-        [
-            "iamc.datapoints",
-            {
-                "model": {"name": "Model 0"},
-                "scenario": {"name": "Scenario 0"},
-                "run": {"default_only": False},
-            },
-        ],
+class TestDataCount:
+    @pytest.mark.parametrize(
+        "repo_name,filters",
         [
-            "iamc.datapoints",
-            {
-                "scenario": {"name__like": "Scenario *"},
-                "run": {"default_only": False},
-            },
-        ],
-        [
-            "iamc.datapoints",
-            {
-                "model": {"name__like": "Model *"},
-                "unit": {"name__in": [f"Unit {i}" for i in range(10)]},
-                "variable": {"name__like": "Variable 1*"},
-                "region": {"name__in": [f"Region {i}" for i in range(10)]},
-                "run": {"default_only": False},
-            },
-        ],
-        [
-            "regions",
-            {
-                "name__like": "Region 1*",
-                "iamc": {
+            [
+                "iamc.datapoints",
+                {
+                    "model": {"name": "Model 0"},
+                    "scenario": {"name": "Scenario 0"},
                     "run": {"default_only": False},
                 },
-            },
-        ],
-        [
-            "models",
-            {
-                "name__like": "Model *",
-                "iamc": True,
-            },
-        ],
-        [
-            "scenarios",
-            {
-                "name__like": "Scenario *",
-                "iamc": {
-                    "variable": {"name__like": "Variable *"},
+            ],
+            [
+                "iamc.datapoints",
+                {
+                    "scenario": {"name__like": "Scenario *"},
                     "run": {"default_only": False},
                 },
-            },
-        ],
-        [
-            "units",
-            {
-                "iamc": {
-                    "variable": {"name__like": "Variable *"},
+            ],
+            [
+                "iamc.datapoints",
+                {
+                    "model": {"name__like": "Model *"},
+                    "unit": {"name__in": [f"Unit {i}" for i in range(10)]},
+                    "variable": {"name__like": "Variable 1*"},
+                    "region": {"name__in": [f"Region {i}" for i in range(10)]},
                     "run": {"default_only": False},
                 },
-            },
+            ],
+            [
+                "regions",
+                {
+                    "name__like": "Region 1*",
+                    "iamc": {
+                        "run": {"default_only": False},
+                    },
+                },
+            ],
+            [
+                "models",
+                {
+                    "name__like": "Model *",
+                    "iamc": True,
+                },
+            ],
+            [
+                "scenarios",
+                {
+                    "name__like": "Scenario *",
+                    "iamc": {
+                        "variable": {"name__like": "Variable *"},
+                        "run": {"default_only": False},
+                    },
+                },
+            ],
+            [
+                "units",
+                {
+                    "iamc": {
+                        "variable": {"name__like": "Variable *"},
+                        "run": {"default_only": False},
+                    },
+                },
+            ],
         ],
-    ],
-)
-def test_count(db_platform_big: ixmp4.Platform, repo_name, filters):
-    repo = deepgetattr(db_platform_big.backend, repo_name)
-    assert len(repo.list(**filters)) == repo.count(**filters)
+    )
+    def test_count(self, db_platform_big: ixmp4.Platform, repo_name, filters):
+        repo = deepgetattr(db_platform_big.backend, repo_name)
+        assert len(repo.list(**filters)) == repo.count(**filters)