Add a statediff streamer

libraries/shared/streamer/statediff_streamer.go

@@ -0,0 +1,39 @@
+// Copyright 2019 Vulcanize
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package streamer
+
+import (
+	"github.com/ethereum/go-ethereum/rpc"
+	"github.com/ethereum/go-ethereum/statediff"
+	"github.com/vulcanize/vulcanizedb/pkg/core"
+)
+
+type Streamer interface {
+	Stream(chan statediff.Payload) (*rpc.ClientSubscription, error)
+}
+
+type StateDiffStreamer struct {
+	client core.RpcClient
+}
+
+func (streamer *StateDiffStreamer) Stream(payloadChan chan statediff.Payload) (*rpc.ClientSubscription, error) {
+	return streamer.client.Subscribe("statediff", payloadChan, "stream")
+}
+
+func NewStateDiffStreamer(client core.RpcClient) StateDiffStreamer {
+	return StateDiffStreamer{
+		client: client,
+	}
+}

libraries/shared/streamer/statediff_streamer_test.go

@@ -0,0 +1,36 @@
+// Copyright 2019 Vulcanize
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package streamer_test
+
+import (
+	"github.com/ethereum/go-ethereum/statediff"
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+	"github.com/vulcanize/vulcanizedb/libraries/shared/streamer"
+	"github.com/vulcanize/vulcanizedb/pkg/fakes"
+)
+
+var _ = Describe("StateDiff Streamer", func() {
+	It("subscribes to the geth statediff service", func() {
+		client := &fakes.MockRpcClient{}
+		streamer := streamer.NewStateDiffStreamer(client)
+		payloadChan := make(chan statediff.Payload)
+		_, err := streamer.Stream(payloadChan)
+		Expect(err).NotTo(HaveOccurred())
+
+		client.AssertSubscribeCalledWith("statediff", payloadChan, []interface{}{"stream"})
+	})
+})
+

libraries/shared/streamer/streamer_suite_test.go

@@ -0,0 +1,13 @@
+package streamer_test
+
+import (
+	"testing"
+
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+)
+
+func TestStreamer(t *testing.T) {
+	RegisterFailHandler(Fail)
+	RunSpecs(t, "Streamer Suite")
+}