[Fleet] Add test config change policy ID

Author: nchaulet

internal/pkg/server/agent_test.go

@@ -277,7 +277,11 @@ func Test_Agent_configFromUnits(t *testing.T) {
 			})
 
 		a := &Agent{
-			cliCfg:     ucfg.New(),
+			cliCfg: ucfg.MustNewFrom(map[string]interface{}{
+				"policy": map[string]interface{}{
+					"id": "test-policy",
+				},
+			}),
 			agent:      mockAgent,
 			inputUnit:  mockInClient,
 			outputUnit: mockOutClient,
@@ -287,6 +291,7 @@ func Test_Agent_configFromUnits(t *testing.T) {
 		require.NoError(t, err)
 		require.Len(t, cfg.Inputs, 1)
 		assert.Equal(t, "fleet-server", cfg.Inputs[0].Type)
+		assert.Equal(t, "test-policy", cfg.Inputs[0].Policy.ID)
 		assert.Equal(t, "0.0.0.0", cfg.Inputs[0].Server.Host)
 		assert.True(t, cfg.Inputs[0].Server.Instrumentation.Enabled)
 		assert.False(t, cfg.Inputs[0].Server.Instrumentation.TLS.SkipVerify)