feat: return an error in case agglayer returns certificate with heigh…

…t lower than in local storage (0xPolygon#209)

aggsender/aggsender.go

@@ -665,19 +665,24 @@ func (a *AggSender) checkLastCertificateFromAgglayer(ctx context.Context) error
 		return nil
 	}
 	// CASE 2.1: certificate in storage but not in agglayer
-	// this is a non-sense, so thrown an error
+	// this is a non-sense, so throw an error
 	if localLastCert != nil && aggLayerLastCert == nil {
-		return fmt.Errorf("recovery: certificate in storage but not in agglayer. Inconsistency")
+		return fmt.Errorf("recovery: certificate exists in storage but not in agglayer. Inconsistency")
 	}
-	// CASE 3: aggsender stopped between sending to agglayer and storing on DB
+	// CASE 3.1: the certificate on the agglayer has less height than the one stored in the local storage
+	if aggLayerLastCert.Height < localLastCert.Height {
+		return fmt.Errorf("recovery: the last certificate in the agglayer has less height (%d) "+
+			"than the one in the local storage (%d)", aggLayerLastCert.Height, localLastCert.Height)
+	}
+	// CASE 3.2: aggsender stopped between sending to agglayer and storing to the local storage
 	if aggLayerLastCert.Height == localLastCert.Height+1 {
-		a.log.Infof("recovery: AggLayer have next cert (height:%d), so is a recovery case: storing cert: %s",
-			aggLayerLastCert.Height, localLastCert.String())
+		a.log.Infof("recovery: AggLayer has the next cert (height: %d), so is a recovery case: storing cert: %s",
+			aggLayerLastCert.Height, aggLayerLastCert.String())
 		// we need to store the certificate in the local storage.
 		localLastCert, err = a.updateLocalStorageWithAggLayerCert(ctx, aggLayerLastCert)
 		if err != nil {
-			log.Errorf("recovery: error updating status certificate: %s status: %w", aggLayerLastCert.String(), err)
-			return fmt.Errorf("recovery: error updating certificate status: %w", err)
+			log.Errorf("recovery: error updating certificate: %s, reason: %w", aggLayerLastCert.String(), err)
+			return fmt.Errorf("recovery: error updating certificate: %w", err)
 		}
 	}
 	// CASE 4: AggSender and AggLayer are not on the same page

aggsender/aggsender_test.go

@@ -1832,8 +1832,21 @@ func TestCheckLastCertificateFromAgglayer_Case2_1NoCertRemoteButCertLocal(t *tes
 	require.Error(t, err)
 }
 
-// CASE 3: AggSender and AggLayer not same certificateID. AggLayer has a new certificate
-func TestCheckLastCertificateFromAgglayer_Case3Mismatch(t *testing.T) {
+// CASE 3.1: the certificate on the agglayer has less height than the one stored in the local storage
+func TestCheckLastCertificateFromAgglayer_Case3_1LessHeight(t *testing.T) {
+	testData := newAggsenderTestData(t, testDataFlagMockStorage)
+	testData.l2syncerMock.EXPECT().OriginNetwork().Return(networkIDTest).Once()
+	testData.agglayerClientMock.EXPECT().GetLatestKnownCertificateHeader(networkIDTest).
+		Return(certInfoToCertHeader(&testData.testCerts[0], networkIDTest), nil).Once()
+	testData.storageMock.EXPECT().GetLastSentCertificate().Return(&testData.testCerts[1], nil)
+
+	err := testData.sut.checkLastCertificateFromAgglayer(testData.ctx)
+
+	require.ErrorContains(t, err, "recovery: the last certificate in the agglayer has less height (1) than the one in the local storage (2)")
+}
+
+// CASE 3.2: AggSender and AggLayer not same height. AggLayer has a new certificate
+func TestCheckLastCertificateFromAgglayer_Case3_2Mismatch(t *testing.T) {
 	testData := newAggsenderTestData(t, testDataFlagMockStorage)
 	testData.l2syncerMock.EXPECT().OriginNetwork().Return(networkIDTest).Once()
 	testData.agglayerClientMock.EXPECT().GetLatestKnownCertificateHeader(networkIDTest).