shill: Check modem proxy validity before Disconnecting.

BUG=chromium-os:32668
TEST=Unit tests, cellular_Smoke, cellular_ModemControl

Change-Id: I457fe576317a89216efb203c0b90e4279e6f8c6a
Reviewed-on: https://gerrit.chromium.org/gerrit/28109
Reviewed-by: Thieu Le <thieule@chromium.org>
Tested-by: Thieu Le <thieule@chromium.org>
Commit-Ready: Thieu Le <thieule@chromium.org>
diff --git a/cellular_capability_universal_unittest.cc b/cellular_capability_universal_unittest.cc
index f466b62..5960dad 100644
--- a/cellular_capability_universal_unittest.cc
+++ b/cellular_capability_universal_unittest.cc
@@ -148,6 +148,10 @@
     capability_->modem_simple_proxy_.reset(modem_simple_proxy_.release());
   }
 
+  void ReleaseCapabilityProxies() {
+    capability_->ReleaseProxies();
+  }
+
   MOCK_METHOD1(TestCallback, void(const Error &error));
 
  protected:
@@ -345,13 +349,23 @@
 TEST_F(CellularCapabilityUniversalTest, DisconnectModemNoBearer) {
   Error error;
   ResultCallback disconnect_callback;
-  mm1::MockModemSimpleProxy *modem_simple_proxy = modem_simple_proxy_.get();
-  EXPECT_CALL(*modem_simple_proxy,
+  EXPECT_CALL(*modem_simple_proxy_,
               Disconnect(_, _, _, CellularCapability::kTimeoutDefault))
       .Times(0);
   capability_->Disconnect(&error, disconnect_callback);
 }
 
+TEST_F(CellularCapabilityUniversalTest, DisconnectNoProxy) {
+  Error error;
+  ResultCallback disconnect_callback;
+  capability_->bearer_path_ = "/foo";
+  EXPECT_CALL(*modem_simple_proxy_,
+              Disconnect(_, _, _, CellularCapability::kTimeoutDefault))
+      .Times(0);
+  ReleaseCapabilityProxies();
+  capability_->Disconnect(&error, disconnect_callback);
+}
+
 TEST_F(CellularCapabilityUniversalTest, PropertiesChanged) {
   // Set up mock modem properties
   DBusPropertiesMap modem_properties;