diff --git a/betty/test_utils/ancestry/event_type.py b/betty/test_utils/ancestry/event_type.py
index e40bb9615..0085fdeff 100644
--- a/betty/test_utils/ancestry/event_type.py
+++ b/betty/test_utils/ancestry/event_type.py
@@ -5,7 +5,11 @@
 from __future__ import annotations
 
 from betty.ancestry.event_type import EventType
-from betty.test_utils.plugin import DummyPlugin, PluginTestBase
+from betty.test_utils.plugin import (
+    DummyPlugin,
+    PluginTestBase,
+    assert_plugin_identifier,
+)
 
 
 class EventTypeTestBase(PluginTestBase[EventType]):
@@ -13,7 +17,25 @@ class EventTypeTestBase(PluginTestBase[EventType]):
     A base class for testing :py:class:`betty.ancestry.event_type.EventType` implementations.
     """
 
-    pass
+    async def test_comes_after(self) -> None:
+        """
+        Tests :py:meth:`betty.ancestry.event_type.EventType.comes_after` implementations.
+        """
+        for event_type_id in self.get_sut_class().comes_after():
+            assert_plugin_identifier(
+                event_type_id,
+                EventType,  # type: ignore[type-abstract]
+            )
+
+    async def test_comes_before(self) -> None:
+        """
+        Tests :py:meth:`betty.ancestry.event_type.EventType.comes_before` implementations.
+        """
+        for event_type_id in self.get_sut_class().comes_before():
+            assert_plugin_identifier(
+                event_type_id,
+                EventType,  # type: ignore[type-abstract]
+            )
 
 
 class DummyEventType(DummyPlugin, EventType):