Test reconnect VpnManager VPN with always on enabled

Verify reconnect using startVpnProfile with the same package with
always-on package should work without exception.

Bug: 235322391
Test: atest FrameworksNetTests
Change-Id: I9a780d970208032e2468e9c5b3334373627c6a20
diff --git a/tests/unit/java/com/android/server/connectivity/VpnTest.java b/tests/unit/java/com/android/server/connectivity/VpnTest.java
index b93bac0..5c1992d 100644
--- a/tests/unit/java/com/android/server/connectivity/VpnTest.java
+++ b/tests/unit/java/com/android/server/connectivity/VpnTest.java
@@ -1360,6 +1360,31 @@
     }
 
     @Test
+    public void testReconnectVpnManagerVpnWithAlwaysOnEnabled() throws Exception {
+        final Vpn vpn = createVpnAndSetupUidChecks(AppOpsManager.OPSTR_ACTIVATE_PLATFORM_VPN);
+        when(mVpnProfileStore.get(vpn.getProfileNameForPackage(TEST_VPN_PKG)))
+                .thenReturn(mVpnProfile.encode());
+        vpn.startVpnProfile(TEST_VPN_PKG);
+        verifyPlatformVpnIsActivated(TEST_VPN_PKG);
+
+        // Enable VPN always-on for TEST_VPN_PKG.
+        assertTrue(vpn.setAlwaysOnPackage(TEST_VPN_PKG, false /* lockdown */,
+                null /* lockdownAllowlist */));
+
+        // Reset to verify next startVpnProfile.
+        reset(mAppOps);
+
+        vpn.stopVpnProfile(TEST_VPN_PKG);
+
+        // Reconnect the vpn with different package will cause exception.
+        assertThrows(SecurityException.class, () -> vpn.startVpnProfile(PKGS[0]));
+
+        // Reconnect the vpn again with the vpn always on package w/o exception.
+        vpn.startVpnProfile(TEST_VPN_PKG);
+        verifyPlatformVpnIsActivated(TEST_VPN_PKG);
+    }
+
+    @Test
     public void testSetPackageAuthorizationVpnService() throws Exception {
         final Vpn vpn = createVpnAndSetupUidChecks();