Merge pull request #156 from vulcanize/contract-watcher-init

Enable contractWatcher without prior headerSync

Author: Rob Mulholand

integration_test/contract_watcher_header_sync_transformer_test.go

@@ -78,11 +78,10 @@ var _ = Describe("contractWatcher headerSync transformer", func() {
 			Expect(c.Address).To(Equal(tusdAddr))
 		})
 
-		It("Fails to initialize if first and block cannot be fetched from vDB headers table", func() {
+		It("initializes when no headers available in db", func() {
 			t := transformer.NewTransformer(test_helpers.TusdConfig, blockChain, db)
 			err = t.Init()
-			Expect(err).To(HaveOccurred())
-			Expect(err.Error()).To(ContainSubstring("no rows in result set"))
+			Expect(err).ToNot(HaveOccurred())
 		})
 
 		It("Does nothing if nothing if no addresses are configured", func() {

pkg/contract_watcher/header/transformer/transformer.go

@@ -17,6 +17,7 @@
 package transformer
 
 import (
+	"database/sql"
 	"errors"
 	"fmt"
 	"strings"
@@ -124,7 +125,11 @@ func (tr *Transformer) Init() error {
 		// Get first block and most recent block number in the header repo
 		firstBlock, retrieveErr := tr.Retriever.RetrieveFirstBlock()
 		if retrieveErr != nil {
-			return fmt.Errorf("error retrieving first block: %s", retrieveErr.Error())
+			if retrieveErr == sql.ErrNoRows {
+				firstBlock = 0
+			} else {
+				return fmt.Errorf("error retrieving first block: %s", retrieveErr.Error())
+			}
 		}
 
 		// Set to specified range if it falls within the bounds

pkg/contract_watcher/header/transformer/transformer_test.go

@@ -17,6 +17,7 @@
 package transformer_test
 
 import (
+	"database/sql"
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
 
@@ -101,7 +102,17 @@ var _ = Describe("Transformer", func() {
 			Expect(c.Address).To(Equal(fakeAddress))
 		})
 
-		It("Fails to initialize if first block cannot be fetched from vDB headers table", func() {
+		It("uses first block from config if vDB headers table has no rows", func() {
+			blockRetriever := &fakes.MockHeaderSyncBlockRetriever{}
+			blockRetriever.FirstBlockErr = sql.ErrNoRows
+			t := getFakeTransformer(blockRetriever, &fakes.MockParser{}, &fakes.MockPoller{})
+
+			err := t.Init()
+
+			Expect(err).ToNot(HaveOccurred())
+		})
+
+		It("returns error if fetching first block fails for other reason", func() {
 			blockRetriever := &fakes.MockHeaderSyncBlockRetriever{}
 			blockRetriever.FirstBlockErr = fakes.FakeError
 			t := getFakeTransformer(blockRetriever, &fakes.MockParser{}, &fakes.MockPoller{})