mgmt: add FaceStatus::unsetExpirationPeriod()

For consistency with Route.

Change-Id: Ieac12ebd7fc7270c03d331c48747bd913f79fef9
Refs: #3903
diff --git a/tests/unit-tests/mgmt/nfd/face-status.t.cpp b/tests/unit-tests/mgmt/nfd/face-status.t.cpp
index 47fefae..d2342f2 100644
--- a/tests/unit-tests/mgmt/nfd/face-status.t.cpp
+++ b/tests/unit-tests/mgmt/nfd/face-status.t.cpp
@@ -130,6 +130,19 @@
                     "     )");
 }
 
+BOOST_AUTO_TEST_CASE(ExpirationPeriod)
+{
+  FaceStatus status;
+  BOOST_CHECK_EQUAL(status.hasExpirationPeriod(), false);
+
+  status.setExpirationPeriod(time::minutes(1));
+  BOOST_REQUIRE_EQUAL(status.hasExpirationPeriod(), true);
+  BOOST_CHECK_EQUAL(status.getExpirationPeriod(), time::minutes(1));
+
+  status.unsetExpirationPeriod();
+  BOOST_CHECK_EQUAL(status.hasExpirationPeriod(), false);
+}
+
 BOOST_AUTO_TEST_CASE(FlagBit)
 {
   FaceStatus status;