feat: report a FreeBSD host as needing a reboot when its installed kernel is not the running one

HOST_STATUS_COMMAND also prints freebsd-version -k and -r where
freebsd-version exists. When the two differ, a kernel update was installed
and is not running yet, so the host needs a reboot. When they match, it does
not.

tests/test_host_status.py

@@ -198,3 +198,48 @@ class TestHostStatusMixin:
 
     def test_not_every_os_driver_has_it(self):
         assert not hasattr(OSDriver, "get_host_status")
+
+
+class TestFreeBSD:
+    """freebsd-version -k names the installed kernel, -r the running one; a
+    patch that replaced the kernel shows as the two differing until the host
+    boots it. Recorded on a FreeBSD 15.1 host (NetOrk/netork#799)."""
+
+    #: What the command printed there before this section existed.
+    BEFORE = (
+        "HSTAT_BEGIN\n[kernel]\n15.1-RELEASE\n[modules]\n[timers]\n"
+        "apt-daily-upgrade.timer \ndnf-automatic.timer \ndnf-automatic-install.timer \n"
+        "HSTAT_END\n"
+    )
+
+    @staticmethod
+    def _report(installed: str, running: str) -> str:
+        return (
+            f"HSTAT_BEGIN\n[kernel]\n{running}\n[modules]\n"
+            f"[freebsd-kernel]\n{installed}\n[freebsd-running]\n{running}\n"
+            "[timers]\napt-daily-upgrade.timer \nHSTAT_END\n"
+        )
+
+    def test_without_the_section_it_is_unknown(self):
+        assert parse_host_status(self.BEFORE)["reboot_required"] is None
+
+    def test_the_running_kernel_is_the_installed_one(self):
+        status = parse_host_status(self._report("15.1-RELEASE-p4", "15.1-RELEASE-p4"))
+        assert status["reboot_required"] is False
+        assert status["reboot_reason"] is None
+
+    def test_a_patched_kernel_waits_for_a_reboot(self):
+        status = parse_host_status(self._report("15.1-RELEASE-p5", "15.1-RELEASE-p4"))
+        assert status["reboot_required"] is True
+        assert status["reboot_reason"] == (
+            "kernel 15.1-RELEASE-p5 installed, 15.1-RELEASE-p4 running"
+        )
+
+    def test_freebsd_does_not_patch_itself_as_far_as_netork_can_tell(self):
+        status = parse_host_status(self._report("15.1-RELEASE", "15.1-RELEASE"))
+        assert status["auto_updates"] is None
+
+    def test_the_command_asks_only_where_freebsd_version_exists(self):
+        assert "command -v freebsd-version" in HOST_STATUS_COMMAND
+        assert "freebsd-version -k" in HOST_STATUS_COMMAND
+        assert "freebsd-version -r" in HOST_STATUS_COMMAND