diff --git a/tests/test_module_system.py b/tests/test_module_system.py
index 7392084..4ba37d0 100644
--- a/tests/test_module_system.py
+++ b/tests/test_module_system.py
@@ -6,6 +6,7 @@ import base64
 import json
 import os
 import re
+import runpy
 import shlex
 import shutil
 import stat
@@ -3079,27 +3080,21 @@ finally:
         self.assertEqual("stable", validation["channel"])
 
     def test_release_catalog_generator_reads_manifest_interface_contracts(self) -> None:
-        root = Path(tempfile.mkdtemp(prefix="govoplan-release-catalog-generator-", dir=_TEST_ROOT))
-        catalog_path = root / "catalog.json"
-
-        result = subprocess.run(
-            [
-                sys.executable,
-                str(Path(__file__).resolve().parents[2] / "govoplan" / "tools" / "generate-release-catalog.py"),
-                "--version",
-                "0.1.7",
-                "--catalog-output",
-                str(catalog_path),
-            ],
-            cwd=str(Path(__file__).resolve().parents[1]),
-            env={**os.environ.copy(), "GOVOPLAN_CORE_ROOT": str(Path(__file__).resolve().parents[1])},
-            text=True,
-            capture_output=True,
-            check=False,
+        generator = runpy.run_path(
+            str(Path(__file__).resolve().parents[2] / "govoplan" / "tools" / "release" / "generate-release-catalog.py"),
+            run_name="govoplan_release_catalog_contract_test",
+        )
+        generated_at = generator["datetime"].now(tz=generator["UTC"])
+        catalog = generator["_catalog_payload"](
+            version="0.1.9",
+            tag="v0.1.9",
+            channel="test",
+            sequence=1,
+            generated_at=generated_at,
+            expires_at=generated_at + generator["timedelta"](days=1),
+            repository_base="git+ssh://git@example.test/add-ideas",
+            public_base_url="https://example.test",
         )
-
-        self.assertEqual(0, result.returncode, result.stderr)
-        catalog = json.loads(catalog_path.read_text(encoding="utf-8"))
         modules = {item["module_id"]: item for item in catalog["modules"]}
 
         self.assertIn({"name": "files.campaign_attachments", "version": "0.1.6"}, modules["files"]["provides_interfaces"])