Refactor to use listener

* This removes some duplication between the fake blockchain and
   geth blockchain.
 * This pulls the observers into the blockchain listener

integration_test/geth_blockchain_test.go

@@ -1,48 +1,40 @@
 package integration_test
 
 import (
-	"fmt"
 	"path"
-	"path/filepath"
 	"runtime"
 
 	"github.com/8thlight/vulcanizedb/core"
+	"github.com/8thlight/vulcanizedb/fakes"
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
 )
 
 var (
 	_, filename, _, _ = runtime.Caller(0)
-	basepath          = filepath.Dir(filename)
 )
 
 func RunTimePath() string {
 	return path.Join(path.Dir(filename), "../")
 }
 
-type ObserverWithChannel struct {
-	blocks chan core.Block
-}
-
-func (observer *ObserverWithChannel) NotifyBlockAdded(block core.Block) {
-	fmt.Println("Block: ", block.Number)
-	observer.blocks <- block
-}
-
 var _ = Describe("Reading from the Geth blockchain", func() {
 
-	It("reads two blocks with incrementing numbers", func(done Done) {
-		addedBlock := make(chan core.Block, 10)
-		observer := &ObserverWithChannel{addedBlock}
+	It("reads two block with listener", func(done Done) {
+		observer := fakes.NewFakeBlockchainObserverTwo()
+		blockchain := core.NewGethBlockchain(RunTimePath() + "/test_data_dir/geth.ipc")
+		observers := []core.BlockchainObserver{observer}
+		listener := core.NewBlockchainListener(blockchain, observers)
+		go listener.Start()
 
-		var blockchain core.Blockchain = core.NewGethBlockchain(RunTimePath() + "/test_data_dir/geth.ipc")
-		blockchain.RegisterObserver(observer)
+		<-observer.WasNotified
+		firstBlock := observer.LastBlock()
+		Expect(firstBlock).NotTo(BeNil())
 
-		go blockchain.SubscribeToEvents()
+		<-observer.WasNotified
+		secondBlock := observer.LastBlock()
+		Expect(secondBlock).NotTo(BeNil())
 
-		firstBlock := <-addedBlock
-		Expect(firstBlock).ShouldNot(BeNil())
-		secondBlock := <-addedBlock
 		Expect(firstBlock.Number + 1).Should(Equal(secondBlock.Number))
 
 		close(done)