Fix a crash with Faker installed and plugin disabled

Fixes #718.

Author: adamchainz

CHANGELOG.rst

@@ -2,6 +2,10 @@
 Changelog
 =========
 
+* Fix a crash with Faker installed when explicitly enabling and disabling the plugin (via ``-p randomly -p no:randomly``).
+
+  Thanks to mojosan77 for the report in `Issue #718 <https://github.com/pytest-dev/pytest-randomly/issues/718>`__.
+
 * Drop Python 3.9 support.
 
 4.0.1 (2025-09-12)

src/pytest_randomly/__init__.py

@@ -265,8 +265,12 @@ def _crc32(string: str) -> int:
 if have_faker:  # pragma: no branch
 
     @fixture(autouse=True)
-    def faker_seed(pytestconfig: Config, request: SubRequest) -> int:
-        result: int = pytestconfig.getoption("randomly_seed") + _crc32(
-            request.node.nodeid
-        )
-        return result
+    def faker_seed(pytestconfig: Config, request: SubRequest) -> Any:
+        from faker.contrib.pytest.plugin import DEFAULT_SEED
+
+        seed = pytestconfig.getoption("randomly_seed", None)
+        if seed is None:
+            return DEFAULT_SEED
+        else:
+            result: int = +_crc32(request.node.nodeid)
+            return result

tests/test_pytest_randomly.py

@@ -633,6 +633,23 @@ def test_two(faker):
     out.assert_outcomes(passed=2)
 
 
+def test_faker_enabled_disabled(monkeypatch, ourtester):
+    monkeypatch.setattr(ourtester, "_method", "subprocess")
+    ourtester.makepyfile(
+        test_one="""
+        from faker import Faker
+
+        fake = Faker()
+
+        def test_one():
+            assert fake.name()
+        """
+    )
+
+    out = ourtester.runpytest("-p", "randomly", "-p", "no:randomly", "-p", "no:faker")
+    out.assert_outcomes(passed=1)
+
+
 def test_model_bakery(ourtester):
     """
     Check the Model Bakery random generator is reset between tests.