Initialize the random seed without requiring a report header

CHANGELOG.rst

@@ -7,6 +7,8 @@ Unreleased
 
 * Drop Python 3.10 support.
 
+* Initialize the configured seed when the report header is disabled, including quiet output and runs without the terminal plugin.
+
 5.0.0 (2026-09-01)
 ------------------
 

src/pytest_randomly/__init__.py

@@ -14,7 +14,7 @@
 from _pytest.config.argparsing import Parser
 from _pytest.fixtures import SubRequest
 from _pytest.nodes import Item
-from pytest import Collector, fixture, hookimpl
+from pytest import Collector, Session, fixture, hookimpl
 
 # factory-boy
 try:
@@ -184,9 +184,12 @@ def _reseed(config: Config, offset: int = 0) -> int:
     return seed
 
 
+def pytest_sessionstart(session: Session) -> None:
+    _reseed(session.config)
+
+
 def pytest_report_header(config: Config) -> str:
     seed = config.getoption("randomly_seed")
-    _reseed(config)
     return f"Using --randomly-seed={seed}"
 
 

tests/test_pytest_randomly.py

@@ -58,6 +58,32 @@ def test_it_reports_a_header_when_set(simpletester):
     assert lines == ["Using --randomly-seed=10"]
 
 
+@pytest.mark.parametrize(
+    "output_args", [(), ("-q",), ("-qq",), ("--no-header",), ("-p", "no:terminal")]
+)
+def test_initial_seed_does_not_require_a_report_header(ourtester, output_args):
+    ourtester.makepyfile(
+        test_one="""
+        import random
+
+        expected = random.Random(123)
+
+        def test_a():
+            assert random.random() == expected.random()
+
+        def test_b():
+            assert random.random() == expected.random()
+        """
+    )
+    out = ourtester.runpytest_subprocess(
+        "--randomly-seed=123",
+        "--randomly-dont-reorganize",
+        "--randomly-dont-reset-seed",
+        *output_args,
+    )
+    assert out.ret == 0
+
+
 def test_it_uses_different_random_seeds_per_test(ourtester):
     """
     Run a pair of tests that generate the a number and then assert they got