diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 919c1e7..9b77c5b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -87,7 +87,7 @@ jobs:
         shell: bash
         run: |
           set -euo pipefail
-          mapfile -t ALL < <(git ls-files 'tests/**/test_*.py' \
+          mapfile -t ALL < <(git ls-files ':(glob)tests/**/test_*.py' \
             | grep -v '^tests/sim/' | grep -v '^tests/e2e/' | sort)
           SEL=()
           for i in "${!ALL[@]}"; do
diff --git a/tests/conftest.py b/tests/conftest.py
index 2ccb965..f5da5a2 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -5,11 +5,12 @@
 import subprocess
 import uuid
 from pathlib import Path
-from typing import Literal
 
 import numpy as np
 import pytest
 
+from systemd_probe import classify_systemd_probe
+
 SEQ_LEN = 1024
 SAMPLES_PER_SHARD = 128
 
@@ -115,22 +116,6 @@ def corpus_dir(tmp_path_factory: pytest.TempPathFactory) -> Path:
     return d
 
 
-# Messages meaning "this user/host has no usable system manager", not "the probe broke".
-_SYSTEMD_UNAVAILABLE = (
-    "Interactive authentication required",
-    "Access denied",
-    "Failed to connect to bus",
-    "System has not been booted with systemd",
-    "Permission denied",
-)
-
-
-def _classify_systemd_probe(returncode: int, stderr: str) -> Literal["ok", "unavailable", "error"]:
-    if returncode == 0:
-        return "ok"
-    return "unavailable" if any(m in stderr for m in _SYSTEMD_UNAVAILABLE) else "error"
-
-
 @pytest.fixture(scope="session")
 def systemd_manager() -> None:
     """Skip unless this user may start transient units on the system manager, as the product does.
@@ -158,7 +143,7 @@ def systemd_manager() -> None:
             timeout=30,
             check=False,
         )
-        verdict = _classify_systemd_probe(probe.returncode, probe.stderr)
+        verdict = classify_systemd_probe(probe.returncode, probe.stderr)
         reason = f"rc={probe.returncode} {probe.stderr.strip()[-500:]}"
     except FileNotFoundError as exc:
         verdict, reason = "unavailable", repr(exc)
diff --git a/tests/systemd_probe.py b/tests/systemd_probe.py
new file mode 100644
index 0000000..8ed7231
--- /dev/null
+++ b/tests/systemd_probe.py
@@ -0,0 +1,20 @@
+"""Classification of the `systemd-run` probe result (imported by conftest and its unit test)."""
+
+from __future__ import annotations
+
+from typing import Literal
+
+# Messages meaning "this user/host has no usable system manager", not "the probe broke".
+_SYSTEMD_UNAVAILABLE = (
+    "Interactive authentication required",
+    "Access denied",
+    "Failed to connect to bus",
+    "System has not been booted with systemd",
+    "Permission denied",
+)
+
+
+def classify_systemd_probe(returncode: int, stderr: str) -> Literal["ok", "unavailable", "error"]:
+    if returncode == 0:
+        return "ok"
+    return "unavailable" if any(m in stderr for m in _SYSTEMD_UNAVAILABLE) else "error"
diff --git a/tests/test_systemd_probe_classify.py b/tests/test_systemd_probe_classify.py
index 59c8bf3..07b4efa 100644
--- a/tests/test_systemd_probe_classify.py
+++ b/tests/test_systemd_probe_classify.py
@@ -2,7 +2,7 @@
 
 import pytest
 
-from conftest import _classify_systemd_probe
+from systemd_probe import classify_systemd_probe
 
 DENIED = [
     "Failed to start transient service unit: Interactive authentication required.",
@@ -14,12 +14,12 @@
 
 
 def test_ok() -> None:
-    assert _classify_systemd_probe(0, "") == "ok"
+    assert classify_systemd_probe(0, "") == "ok"
 
 
 @pytest.mark.parametrize("stderr", DENIED)
 def test_unavailable(stderr: str) -> None:
-    assert _classify_systemd_probe(1, stderr) == "unavailable"
+    assert classify_systemd_probe(1, stderr) == "unavailable"
 
 
 @pytest.mark.parametrize(
@@ -27,4 +27,4 @@ def test_unavailable(stderr: str) -> None:
     ["Failed to start transient service unit: Resource temporarily unavailable (EAGAIN)", ""],
 )
 def test_error(stderr: str) -> None:
-    assert _classify_systemd_probe(1, stderr) == "error"
+    assert classify_systemd_probe(1, stderr) == "error"