diff --git a/tests/unit/services/cwmp/gpn_circuit_breaker.spec.ts b/tests/unit/services/cwmp/gpn_circuit_breaker.spec.ts
index 1de36b4..03c52cc 100644
--- a/tests/unit/services/cwmp/gpn_circuit_breaker.spec.ts
+++ b/tests/unit/services/cwmp/gpn_circuit_breaker.spec.ts
@@ -105,6 +105,59 @@ describe('GPN Circuit Breaker — DiscoveringParametersState', () => {
     expect(response).toContain('GetParameterNames')
   })
 
+  it('DiscoveringParametersState processes GPN response and stores parameters', async () => {
+    const device = makeDevice()
+    device.setGpnStatus('unknown')
+    const taskQueue = new CWMPTaskQueue()
+    const sm = new MainStateMachine(device, 'session-1', taskQueue)
+
+    // Start: IdleState → DiscoveringParametersState → sends GPN
+    await sm.start()
+
+    // Simulate a successful GPN response with ParameterInfoStruct list
+    const gpnResponse = {
+      ParameterList: {
+        ParameterInfoStruct: [
+          { Name: 'InternetGatewayDevice.ManagementServer.', Writable: false },
+          { Name: 'InternetGatewayDevice.ManagementServer.PeriodicInformInterval', Writable: true },
+          { Name: 'InternetGatewayDevice.ManagementServer.PeriodicInformEnable', Writable: true },
+          { Name: 'InternetGatewayDevice.ManagementServer.URL', Writable: true },
+          { Name: 'InternetGatewayDevice.ManagementServer.ConnectionRequestURL', Writable: false },
+        ],
+      },
+    }
+    await sm.handleResponse(true, gpnResponse)
+
+    // gpnStatus should be 'supported'
+    expect(device.gpnStatus).toBe('supported')
+
+    // Writable params should be stored as parameters
+    const periodicInterval = device.getParameter('InternetGatewayDevice.ManagementServer.PeriodicInformInterval')
+    expect(periodicInterval).not.toBeNull()
+
+    // Read-only params should be stored as properties
+    const connUrl = device.getProperty('InternetGatewayDevice.ManagementServer.ConnectionRequestURL')
+    expect(connUrl).not.toBeNull()
+
+    // Object paths (ending with dot) should NOT be stored
+    const obj = device.getParameter('InternetGatewayDevice.ManagementServer.')
+    expect(obj).toBeNull()
+  })
+
+  it('DiscoveringParametersState sets gpnStatus supported even with empty param list', async () => {
+    const device = makeDevice()
+    device.setGpnStatus('unknown')
+    const taskQueue = new CWMPTaskQueue()
+    const sm = new MainStateMachine(device, 'session-1', taskQueue)
+
+    await sm.start()
+
+    // Respond with empty list
+    await sm.handleResponse(true, { ParameterList: { ParameterInfoStruct: [] } })
+
+    expect(device.gpnStatus).toBe('supported')
+  })
+
   it('DiscoveringParametersState calls recordGpnFailure and persists on fault', async () => {
     const device = makeDevice()
     device.setGpnStatus('unknown')