fix: last sent certificate block underflow

aggsender/aggsender.go

@@ -155,17 +155,8 @@ func (a *AggSender) sendCertificate(ctx context.Context) (*agglayer.SignedCertif
 	if err != nil {
 		return nil, err
 	}
-	previousToBlock := uint64(0)
-	retryCount := 0
-	if lastSentCertificateInfo != nil {
-		previousToBlock = lastSentCertificateInfo.ToBlock
-		if lastSentCertificateInfo.Status == agglayer.InError {
-			// if the last certificate was in error, we need to resend it
-			// from the block before the error
-			previousToBlock = lastSentCertificateInfo.FromBlock - 1
-			retryCount = lastSentCertificateInfo.RetryCount + 1
-		}
-	}
+
+	previousToBlock, retryCount := getLastSentBlockAndRetryCount(lastSentCertificateInfo)
 
 	if previousToBlock >= lasL2BlockSynced {
 		a.log.Infof("no new blocks to send a certificate, last certificate block: %d, last L2 block: %d",
@@ -823,3 +814,26 @@ func NewCertificateInfoFromAgglayerCertHeader(c *agglayer.CertificateHeader) *ty
 	}
 	return res
 }
+
+// getLastSentBlockAndRetryCount returns the last sent block of the last sent certificate
+// if there is no previosly sent certificate, it returns 0 and 0
+func getLastSentBlockAndRetryCount(lastSentCertificateInfo *types.CertificateInfo) (uint64, int) {
+	if lastSentCertificateInfo == nil {
+		return 0, 0
+	}
+
+	retryCount := 0
+	previousToBlock := lastSentCertificateInfo.ToBlock
+
+	if lastSentCertificateInfo.Status == agglayer.InError {
+		// if the last certificate was in error, we need to resend it
+		// from the block before the error
+		if lastSentCertificateInfo.FromBlock > 0 {
+			previousToBlock = lastSentCertificateInfo.FromBlock - 1
+		}
+
+		retryCount = lastSentCertificateInfo.RetryCount + 1
+	}
+
+	return previousToBlock, retryCount
+}

aggsender/aggsender_test.go

@@ -1959,6 +1959,68 @@ func TestLimitSize_MinNumBlocks(t *testing.T) {
 	require.Equal(t, uint64(1), newCert.ToBlock)
 }
 
+func TestGetLastSentBlockAndRetryCount(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name                    string
+		lastSentCertificateInfo *aggsendertypes.CertificateInfo
+		expectedBlock           uint64
+		expectedRetryCount      int
+	}{
+		{
+			name:                    "No last sent certificate",
+			lastSentCertificateInfo: nil,
+			expectedBlock:           0,
+			expectedRetryCount:      0,
+		},
+		{
+			name: "Last sent certificate with no error",
+			lastSentCertificateInfo: &aggsendertypes.CertificateInfo{
+				ToBlock: 10,
+				Status:  agglayer.Settled,
+			},
+			expectedBlock:      10,
+			expectedRetryCount: 0,
+		},
+		{
+			name: "Last sent certificate with error and non-zero FromBlock",
+			lastSentCertificateInfo: &aggsendertypes.CertificateInfo{
+				FromBlock:  5,
+				ToBlock:    10,
+				Status:     agglayer.InError,
+				RetryCount: 1,
+			},
+			expectedBlock:      4,
+			expectedRetryCount: 2,
+		},
+		{
+			name: "Last sent certificate with error and zero FromBlock",
+			lastSentCertificateInfo: &aggsendertypes.CertificateInfo{
+				FromBlock:  0,
+				ToBlock:    10,
+				Status:     agglayer.InError,
+				RetryCount: 1,
+			},
+			expectedBlock:      10,
+			expectedRetryCount: 2,
+		},
+	}
+
+	for _, tt := range tests {
+		tt := tt
+
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			block, retryCount := getLastSentBlockAndRetryCount(tt.lastSentCertificateInfo)
+
+			require.Equal(t, tt.expectedBlock, block)
+			require.Equal(t, tt.expectedRetryCount, retryCount)
+		})
+	}
+}
+
 type testDataFlags = int
 
 const (