diff --git a/agent/test/src/test_core.cc b/agent/test/src/test_core.cc
new file mode 100644
index 0000000..3588f95
--- /dev/null
+++ b/agent/test/src/test_core.cc
@@ -0,0 +1,386 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+
+ * http://www.apache.org/licenses/LICENSE-2.0
+
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include "gtest/gtest.h"
+#include "bal_mocker.h"
+#include "core.h"
+using namespace testing;
+using namespace std;
+
+class TestOltEnable : public Test {
+ protected:
+  virtual void SetUp() {
+  }
+
+  virtual void TearDown() {
+    // Code here will be called immediately after each test
+    // (right before the destructor).
+  }
+};
+
+// This is used to set custom bcmolt_cfg value to bcmolt_cfg pointer coming in
+// bcmolt_cfg_get__bal_state_stub.
+ACTION_P(SetArg1ToBcmOltCfg, value) { *static_cast<bcmolt_olt_cfg*>(arg1) = value; };
+
+
+// Create a mock function for bcmolt_cfg_get__bal_state_stub C++ function
+MOCK_GLOBAL_FUNC2(bcmolt_cfg_get__bal_state_stub, bcmos_errno(bcmolt_oltid, void*));
+
+
+// Test Fixture for OltEnable
+
+// Test 1: OltEnableSuccess case
+TEST_F(TestOltEnable, OltEnableSuccess){
+    // NiceMock is used to suppress 'WillByDefault' return errors.
+    // This is described in https://github.com/arangodb-helper/gtest/blob/master/googlemock/docs/CookBook.md
+    NiceMock<BalMocker> balMock;
+    bcmos_errno host_init_res = BCM_ERR_OK;
+    bcmos_errno bal_cfg_get_stub_res = BCM_ERR_OK;
+    bcmos_errno bal_cfg_get_res = BCM_ERR_NOT_CONNECTED;
+    bcmos_errno olt_oper_res = BCM_ERR_OK;
+
+    bcmolt_olt_cfg olt_cfg = { };
+    bcmolt_olt_key olt_key = { };
+    BCMOLT_CFG_INIT(&olt_cfg, olt, olt_key);
+    olt_cfg.data.bal_state = BCMOLT_BAL_STATE_BAL_AND_SWITCH_READY;
+
+    Status olt_enable_res;
+
+    ON_CALL(balMock, bcmolt_host_init(_)).WillByDefault(Return(host_init_res));
+    EXPECT_GLOBAL_CALL(bcmolt_cfg_get__bal_state_stub, bcmolt_cfg_get__bal_state_stub(_, _))
+                     .WillOnce(DoAll(SetArg1ToBcmOltCfg(olt_cfg), Return(bal_cfg_get_stub_res)));
+    EXPECT_CALL(balMock, bcmolt_cfg_get(_, _))
+                         .Times(BCM_MAX_DEVS_PER_LINE_CARD)
+                         .WillRepeatedly(Return(bal_cfg_get_res));
+    ON_CALL(balMock, bcmolt_oper_submit(_, _)).WillByDefault(Return(olt_oper_res));
+
+    olt_enable_res = Enable_(1, NULL);
+    ASSERT_TRUE( olt_enable_res.error_message() == Status::OK.error_message() );
+}
+
+// Test 2: OltEnableFail_host_init_fail
+TEST_F(TestOltEnable, OltEnableFail_host_init_fail) {
+    // NiceMock is used to suppress 'WillByDefault' return errors.
+    // This is described in https://github.com/arangodb-helper/gtest/blob/master/googlemock/docs/CookBook.md
+    NiceMock<BalMocker> balMock;
+    bcmos_errno host_init_res = BCM_ERR_INTERNAL;
+
+    Status olt_enable_res;
+
+    // Ensure that the state of the OLT is in deactivated to start with..
+    state.deactivate();
+
+    ON_CALL(balMock, bcmolt_host_init(_)).WillByDefault(Return(host_init_res));
+
+    olt_enable_res = Enable_(1, NULL);
+    ASSERT_TRUE( olt_enable_res.error_message() != Status::OK.error_message() );
+}
+
+// Test 3: OltEnableSuccess_PON_Device_Connected
+TEST_F(TestOltEnable, OltEnableSuccess_PON_Device_Connected) {
+
+    // NiceMock is used to suppress 'WillByDefault' return errors.
+    // This is described in https://github.com/arangodb-helper/gtest/blob/master/googlemock/docs/CookBook.md
+    NiceMock<BalMocker> balMock;
+    bcmos_errno host_init_res = BCM_ERR_OK;
+    bcmos_errno bal_cfg_get_stub_res = BCM_ERR_OK;
+    bcmos_errno bal_cfg_get_res = BCM_ERR_OK;
+    bcmos_errno olt_oper_res = BCM_ERR_OK;
+
+    bcmolt_olt_cfg olt_cfg = { };
+    bcmolt_olt_key olt_key = { };
+    BCMOLT_CFG_INIT(&olt_cfg, olt, olt_key);
+    olt_cfg.data.bal_state = BCMOLT_BAL_STATE_BAL_AND_SWITCH_READY;
+
+    Status olt_enable_res;
+
+    // Ensure that the state of the OLT is in deactivated to start with..
+    state.deactivate();
+
+    ON_CALL(balMock, bcmolt_host_init(_)).WillByDefault(Return(host_init_res));
+    EXPECT_GLOBAL_CALL(bcmolt_cfg_get__bal_state_stub, bcmolt_cfg_get__bal_state_stub(_, _))
+                     .WillOnce(DoAll(SetArg1ToBcmOltCfg(olt_cfg), Return(bal_cfg_get_stub_res)));
+    EXPECT_CALL(balMock, bcmolt_cfg_get(_, _))
+                         .Times(BCM_MAX_DEVS_PER_LINE_CARD)
+                         .WillRepeatedly(Return(bal_cfg_get_res));
+
+    olt_enable_res = Enable_(1, NULL);
+    ASSERT_TRUE( olt_enable_res.error_message() == Status::OK.error_message() );
+
+}
+
+// Test 4: OltEnableFail_All_PON_Enable_Fail
+TEST_F(TestOltEnable, OltEnableFail_All_PON_Enable_Fail) {
+
+    // NiceMock is used to suppress 'WillByDefault' return errors.
+    // This is described in https://github.com/arangodb-helper/gtest/blob/master/googlemock/docs/CookBook.md
+    NiceMock<BalMocker> balMock;
+    bcmos_errno host_init_res = BCM_ERR_OK;
+    bcmos_errno bal_cfg_get_stub_res = BCM_ERR_OK;
+    bcmos_errno bal_cfg_get_res = BCM_ERR_NOT_CONNECTED;
+    bcmos_errno olt_oper_res = BCM_ERR_INTERNAL;
+
+    bcmolt_olt_cfg olt_cfg = { };
+    bcmolt_olt_key olt_key = { };
+    BCMOLT_CFG_INIT(&olt_cfg, olt, olt_key);
+    olt_cfg.data.bal_state = BCMOLT_BAL_STATE_BAL_AND_SWITCH_READY;
+
+    Status olt_enable_res;
+
+    // Ensure that the state of the OLT is in deactivated to start with..
+    state.deactivate();
+
+    ON_CALL(balMock, bcmolt_host_init(_)).WillByDefault(Return(host_init_res));
+    EXPECT_GLOBAL_CALL(bcmolt_cfg_get__bal_state_stub, bcmolt_cfg_get__bal_state_stub(_, _))
+                     .WillOnce(DoAll(SetArg1ToBcmOltCfg(olt_cfg), Return(bal_cfg_get_stub_res)));
+    EXPECT_CALL(balMock, bcmolt_cfg_get(_, _))
+                         .Times(BCM_MAX_DEVS_PER_LINE_CARD)
+                         .WillRepeatedly(Return(bal_cfg_get_res));
+    ON_CALL(balMock, bcmolt_oper_submit(_, _)).WillByDefault(Return(olt_oper_res));
+
+    olt_enable_res = Enable_(1, NULL);
+
+    ASSERT_TRUE( olt_enable_res.error_message() != Status::OK.error_message() );
+}
+
+// Test 5 OltEnableSuccess_One_PON_Enable_Fail : One PON device enable fails, but all others succeed.
+TEST_F(TestOltEnable, OltEnableSuccess_One_PON_Enable_Fail) {
+
+    // NiceMock is used to suppress 'WillByDefault' return errors.
+    // This is described in https://github.com/arangodb-helper/gtest/blob/master/googlemock/docs/CookBook.md
+    NiceMock<BalMocker> balMock;
+    bcmos_errno host_init_res = BCM_ERR_OK;
+    bcmos_errno bal_cfg_get_stub_res = BCM_ERR_OK;
+    bcmos_errno bal_cfg_get_res = BCM_ERR_NOT_CONNECTED;
+    bcmos_errno olt_oper_res_fail = BCM_ERR_INTERNAL;
+    bcmos_errno olt_oper_res_success = BCM_ERR_OK;
+
+    bcmolt_olt_cfg olt_cfg = { };
+    bcmolt_olt_key olt_key = { };
+    BCMOLT_CFG_INIT(&olt_cfg, olt, olt_key);
+    olt_cfg.data.bal_state = BCMOLT_BAL_STATE_BAL_AND_SWITCH_READY;
+
+    Status olt_enable_res;
+
+    // Ensure that the state of the OLT is in deactivated to start with..
+    state.deactivate();
+
+    ON_CALL(balMock, bcmolt_host_init(_)).WillByDefault(Return(host_init_res));
+    EXPECT_GLOBAL_CALL(bcmolt_cfg_get__bal_state_stub, bcmolt_cfg_get__bal_state_stub(_, _))
+                     .WillOnce(DoAll(SetArg1ToBcmOltCfg(olt_cfg), Return(bal_cfg_get_stub_res)));
+    EXPECT_CALL(balMock, bcmolt_cfg_get(_, _))
+                         .Times(BCM_MAX_DEVS_PER_LINE_CARD)
+                         .WillRepeatedly(Return(bal_cfg_get_res));
+    // For the the first PON mac device, the activation result will fail, and will succeed for all other PON mac devices.
+    EXPECT_CALL(balMock, bcmolt_oper_submit(_, _))
+                         .WillOnce(Return(olt_oper_res_fail))
+                         .WillRepeatedly(Return(olt_oper_res_success));
+    olt_enable_res = Enable_(1, NULL);
+
+    ASSERT_TRUE( olt_enable_res.error_message() == Status::OK.error_message() );
+}
+
+////////////////////////////////////////////////////////////////////////
+// For testing Enable/Disable functionality
+////////////////////////////////////////////////////////////////////////
+
+int num_of_pon_ports = 16;
+
+// Create a mock function for bcmolt_cfg_get__olt_topology_stub C++ function
+MOCK_GLOBAL_FUNC2(bcmolt_cfg_get__olt_topology_stub, bcmos_errno(bcmolt_oltid, void*));
+
+class TestOltDisableReenable : public Test {
+ protected:
+  virtual void SetUp() {
+    NiceMock<BalMocker> balMock;
+    bcmos_errno bal_cfg_get_stub_res = BCM_ERR_OK;
+
+    bcmolt_olt_cfg olt_cfg = { };
+    bcmolt_olt_key olt_key = { };
+
+    BCMOLT_CFG_INIT(&olt_cfg, olt, olt_key);
+
+    olt_cfg.data.topology.topology_maps.len = num_of_pon_ports;
+    EXPECT_GLOBAL_CALL(bcmolt_cfg_get__olt_topology_stub, bcmolt_cfg_get__olt_topology_stub(_, _))
+                     .WillOnce(DoAll(SetArg1ToBcmOltCfg(olt_cfg), Return(bal_cfg_get_stub_res)));
+
+    ProbeDeviceCapabilities_();
+
+  }
+
+  virtual void TearDown() {
+    // Code here will be called immediately after each test
+    // (right before the destructor).
+  }
+};
+
+
+// Test Fixture for OltDisable
+
+// Test 1: OltDisableSuccess  case
+TEST_F(TestOltDisableReenable, OltDisableSuccess){
+    // NiceMock is used to suppress 'WillByDefault' return errors.
+    // This is described in https://github.com/arangodb-helper/gtest/blob/master/googlemock/docs/CookBook.md
+    NiceMock<BalMocker> balMock;
+    bcmos_errno bal_cfg_get_res = BCM_ERR_OK;
+
+    Status olt_disable_res;
+
+    EXPECT_CALL(balMock, bcmolt_cfg_get(_, _))
+                         .Times(num_of_pon_ports)
+                         .WillRepeatedly(Return(bal_cfg_get_res));
+
+    olt_disable_res = Disable_();
+    ASSERT_TRUE( olt_disable_res.error_message() == Status::OK.error_message() );
+
+}
+
+// Test 2: OltDisableAllPonFailed  case
+TEST_F(TestOltDisableReenable, OltDisableAllPonFailed){
+    // NiceMock is used to suppress 'WillByDefault' return errors.
+    // This is described in https://github.com/arangodb-helper/gtest/blob/master/googlemock/docs/CookBook.md
+    NiceMock<BalMocker> balMock;
+    bcmos_errno bal_cfg_get_res = BCM_ERR_INTERNAL;
+
+    Status olt_disable_res;
+
+    EXPECT_CALL(balMock, bcmolt_cfg_get(_, _))
+                         .Times(num_of_pon_ports)
+                         .WillRepeatedly(Return(bal_cfg_get_res));
+
+    olt_disable_res = Disable_();
+    ASSERT_TRUE( olt_disable_res.error_code() == grpc::StatusCode::INTERNAL);
+}
+
+
+// Test Fixture for OltReenable
+
+// Test 1: OltReenableSuccess  case
+TEST_F(TestOltDisableReenable, OltReenableSuccess){
+    // NiceMock is used to suppress 'WillByDefault' return errors.
+    // This is described in https://github.com/arangodb-helper/gtest/blob/master/googlemock/docs/CookBook.md
+    NiceMock<BalMocker> balMock;
+    bcmos_errno bal_cfg_get_res = BCM_ERR_OK;
+
+    Status olt_reenable_res;
+
+    EXPECT_CALL(balMock, bcmolt_cfg_get(_, _))
+                         .Times(num_of_pon_ports*2)
+                         .WillRepeatedly(Return(bal_cfg_get_res));
+
+    olt_reenable_res = Reenable_();
+    ASSERT_TRUE( olt_reenable_res.error_message() == Status::OK.error_message() );
+
+}
+
+// Test 2: OltReenableAllPonFailed  case
+TEST_F(TestOltDisableReenable, OltReenableAllPonFailed){
+    // NiceMock is used to suppress 'WillByDefault' return errors.
+    // This is described in https://github.com/arangodb-helper/gtest/blob/master/googlemock/docs/CookBook.md
+    NiceMock<BalMocker> balMock;
+    bcmos_errno bal_cfg_get_res = BCM_ERR_OK;
+    bcmos_errno olt_oper_res = BCM_ERR_INTERNAL;
+
+    Status olt_reenable_res;
+
+    EXPECT_CALL(balMock, bcmolt_cfg_get(_, _))
+                         .Times(num_of_pon_ports)
+                         .WillRepeatedly(Return(bal_cfg_get_res));
+    EXPECT_CALL(balMock,bcmolt_oper_submit(_, _))
+                         .Times(num_of_pon_ports)
+                         .WillRepeatedly(Return(olt_oper_res));
+    olt_reenable_res = Reenable_();
+    ASSERT_TRUE( olt_reenable_res.error_code() == grpc::StatusCode::INTERNAL);
+}
+
+////////////////////////////////////////////////////////////////////////////
+// For testing ProbeDeviceCapabilities functionality
+////////////////////////////////////////////////////////////////////////////
+class TestProbeDevCapabilities : public Test {
+    protected:
+        NiceMock<BalMocker> balMock;
+        bcmos_errno olt_res_success = BCM_ERR_OK;
+        bcmos_errno olt_res_fail = BCM_ERR_COMM_FAIL;
+        bcmos_errno dev_res_success = BCM_ERR_OK;
+        bcmos_errno dev_res_fail = BCM_ERR_COMM_FAIL;
+
+        virtual void SetUp() {
+            bcmos_errno bal_cfg_get_stub_res = BCM_ERR_OK;
+
+            bcmolt_olt_cfg olt_cfg = { };
+            bcmolt_olt_key olt_key = { };
+
+            BCMOLT_CFG_INIT(&olt_cfg, olt, olt_key);
+
+            olt_cfg.data.topology.topology_maps.len = num_of_pon_ports;
+        }
+
+        virtual void TearDown() {
+        }
+};
+
+// Test 1 - If querying the OLT fails, the method must return error
+TEST_F(TestProbeDevCapabilities, ProbeDev_OltQueryFailed) {
+
+    EXPECT_GLOBAL_CALL(bcmolt_cfg_get__olt_topology_stub, bcmolt_cfg_get__olt_topology_stub(_,_))
+                     .WillOnce(Return(olt_res_fail));
+
+    Status query_status = ProbeDeviceCapabilities_();
+    ASSERT_TRUE( query_status.error_message() != Status::OK.error_message() );
+}
+
+// Test 2 - If all devices are queried successfully, the method must return Status::OK
+TEST_F(TestProbeDevCapabilities, ProbeDev_OltQuerySucceeded_DevQueriesSucceeded) {
+
+    EXPECT_GLOBAL_CALL(bcmolt_cfg_get__olt_topology_stub, bcmolt_cfg_get__olt_topology_stub(_,_))
+                     .WillOnce(Return(olt_res_success));
+
+    EXPECT_CALL(balMock, bcmolt_cfg_get(_, _))
+        .WillRepeatedly(Return(dev_res_success));
+
+    Status query_status = ProbeDeviceCapabilities_();
+
+    ASSERT_TRUE( query_status.error_message() == Status::OK.error_message() );
+}
+
+// Test 3 - After successfully probing the OLT, even if probing all devices failed, the method must return error
+TEST_F(TestProbeDevCapabilities, ProbedDev_OltQuerySucceeded_AllDevQueriesFailed) {
+
+    EXPECT_GLOBAL_CALL(bcmolt_cfg_get__olt_topology_stub, bcmolt_cfg_get__olt_topology_stub(_,_))
+                     .WillOnce(Return(olt_res_success));
+
+    EXPECT_CALL(balMock, bcmolt_cfg_get(_, _))
+        .WillRepeatedly(Return(dev_res_fail));
+
+    Status query_status = ProbeDeviceCapabilities_();
+
+    ASSERT_TRUE( query_status.error_message() != Status::OK.error_message() );
+}
+
+// Test 4 - After successfully probing the OLT, if probing some devices fail, the method returns success
+TEST_F(TestProbeDevCapabilities, ProbedDev_OltQuerySucceeded_SomeDevQueriesFailed) {
+
+    EXPECT_GLOBAL_CALL(bcmolt_cfg_get__olt_topology_stub, bcmolt_cfg_get__olt_topology_stub(_,_))
+                     .WillOnce(Return(olt_res_success));
+
+    EXPECT_CALL(balMock, bcmolt_cfg_get(_, _))
+        .WillOnce(Return(olt_res_success))
+        .WillRepeatedly(Return(dev_res_fail));
+
+    Status query_status = ProbeDeviceCapabilities_();
+
+    ASSERT_TRUE( query_status.error_message() == Status::OK.error_message() );
+}
+