diff --git a/tests/plugins/test_plugin_enumeration_coverage.py b/tests/plugins/test_plugin_enumeration_coverage.py
new file mode 100644
index 000000000..7e4e94e38
--- /dev/null
+++ b/tests/plugins/test_plugin_enumeration_coverage.py
@@ -0,0 +1,75 @@
+# SPDX-FileCopyrightText: Copyright (c) 2023 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0
+
+"""Contract test for plugin enumeration coverage (garak issue #713).
+
+enumerate_plugins() is the public view of garak's plugin discovery. Its
+contract: every concrete plugin class in a category (probes/detectors/…)
+should be returned by enumerate_plugins(), except base classes — which the
+function deliberately excludes via the ``.base.`` name check.
+
+This test validates that *contract* without re-implementing discovery: it
+collects concrete plugin classes reachable from the category base classes via
+the normal Python subclass registry, filters to the ``garak.<category>.``
+namespace (matching what discovery enumerates), and asserts enumerate_plugins()
+surfaces each one. Base classes are excluded exactly as enumerate_plugins does.
+"""
+
+import importlib
+import inspect
+
+import pytest
+
+from garak import _plugins
+
+CATEGORIES = ("detectors", "probes")
+
+
+def _base_plugin_classes(category: str) -> list[type]:
+    """Concrete base plugin classes for a category (e.g. Detector, Probe)."""
+    base_mod = importlib.import_module(f"garak.{category}.base")
+    return [
+        klass
+        for name, klass in inspect.getmembers(base_mod, inspect.isclass)
+        if klass.__module__.startswith(base_mod.__name__)
+        and not inspect.isabstract(klass)
+    ]
+
+
+def _concrete_plugin_classes(category: str) -> set[str]:
+    """Concrete plugin classes in the garak.<category>. namespace.
+
+    Reachable from the category base classes through the Python subclass
+    registry — the same classes discovery walks. Base classes themselves are
+    excluded, matching enumerate_plugins()'s ``.base.`` skip.
+    """
+    found = set()
+    for base in _base_plugin_classes(category):
+        for sub in base.__subclasses__():
+            if sub.__module__.startswith(f"garak.{category}.") and not sub.__module__.endswith(".base"):
+                name = f"{category}.{sub.__module__.split('.')[-1]}.{sub.__name__}"
+                found.add(name)
+    return found
+
+
+@pytest.mark.parametrize("category", CATEGORIES)
+def test_all_concrete_plugin_classes_are_enumerated(category: str) -> None:
+    """Every concrete plugin class must be returned by enumerate_plugins()."""
+    discovered = _concrete_plugin_classes(category)
+    enumerated = {name for (name, _active) in _plugins.enumerate_plugins(category)}
+
+    missing = sorted(discovered - enumerated)
+    assert missing == [], (
+        f"concrete plugin classes in garak.{category} not picked up by "
+        f"plugin enumeration (see issue #713): {missing}"
+    )
+
+
+@pytest.mark.parametrize("category", CATEGORIES)
+def test_base_classes_excluded_from_enumeration(category: str) -> None:
+    """Base classes must NOT be enumerated (contract: `.base.` is skipped)."""
+    enumerated = {name for (name, _active) in _plugins.enumerate_plugins(category)}
+    base_leaks = sorted(n for n in enumerated if ".base." in n)
+    assert base_leaks == [], (
+        f"base classes should be excluded from enumeration but were found: {base_leaks}"
+    )