diff --git a/fw-update/test/inventory_manager_test.cpp b/fw-update/test/inventory_manager_test.cpp
index 9d80be2..678d9bb 100644
--- a/fw-update/test/inventory_manager_test.cpp
+++ b/fw-update/test/inventory_manager_test.cpp
@@ -19,7 +19,7 @@
         reqHandler(nullptr, event, instanceIdDb, false, seconds(1), 2,
                    milliseconds(100)),
         inventoryManager(reqHandler, instanceIdDb, outDescriptorMap,
-                         outComponentInfoMap)
+                         outDownstreamDescriptorMap, outComponentInfoMap)
     {}
 
     int fd = -1;
@@ -28,6 +28,7 @@
     requester::Handler<requester::Request> reqHandler;
     InventoryManager inventoryManager;
     DescriptorMap outDescriptorMap{};
+    DownstreamDescriptorMap outDownstreamDescriptorMap{};
     ComponentInfoMap outComponentInfoMap{};
 };
 
@@ -100,6 +101,51 @@
     EXPECT_EQ(outDescriptorMap.size(), 0);
 }
 
+TEST_F(InventoryManagerTest, handleQueryDownstreamIdentifierResponse)
+{
+    constexpr uint8_t eid = 1;
+    constexpr uint8_t downstreamDeviceCount = 1;
+    constexpr uint32_t downstreamDeviceLen = 11;
+    constexpr size_t respPayloadLength =
+        PLDM_QUERY_DOWNSTREAM_IDENTIFIERS_RESP_MIN_LEN + downstreamDeviceLen;
+
+    std::array<uint8_t, sizeof(pldm_msg_hdr) + respPayloadLength>
+        queryDownstreamIdentifiersResp{
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x05,
+            0x0B, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x01,
+            0x01, 0x00, 0x04, 0x00, 0x00, 0x00, 0xa0, 0x15};
+    auto responseMsg = new (queryDownstreamIdentifiersResp.data()) pldm_msg;
+
+    inventoryManager.queryDownstreamIdentifiers(eid, responseMsg,
+                                                respPayloadLength);
+
+    DownstreamDevices downstreamDevices = {
+        {0,
+         {{PLDM_FWUP_IANA_ENTERPRISE_ID,
+           std::vector<uint8_t>{0x00, 0x00, 0xa0, 0x15}}}}};
+    DownstreamDescriptorMap refDownstreamDescriptorMap{
+        {eid, downstreamDevices}};
+
+    ASSERT_EQ(outDownstreamDescriptorMap.size(), downstreamDeviceCount);
+    ASSERT_EQ(outDownstreamDescriptorMap.size(),
+              refDownstreamDescriptorMap.size());
+    ASSERT_EQ(outDownstreamDescriptorMap, refDownstreamDescriptorMap);
+}
+
+TEST_F(InventoryManagerTest, handleQueryDownstreamIdentifierResponseErrorCC)
+{
+    constexpr size_t respPayloadLength = 1;
+    constexpr std::array<uint8_t, sizeof(pldm_msg_hdr) + respPayloadLength>
+        queryDownstreamIdentifiersResp{0x00, 0x00, 0x00, 0x01};
+    const auto responseMsg =
+        new (const_cast<unsigned char*>(queryDownstreamIdentifiersResp.data()))
+            pldm_msg;
+    inventoryManager.queryDownstreamIdentifiers(1, responseMsg,
+                                                respPayloadLength);
+
+    ASSERT_EQ(outDownstreamDescriptorMap.size(), 0);
+}
+
 TEST_F(InventoryManagerTest, getFirmwareParametersResponse)
 {
     // constexpr uint16_t compCount = 2;