Invoke subgraph handler in watcher event processing (#34)

* Invoke subgraph handler in watcher event processing

* Fix error when invoking subgraph handler

* Parse events using event signature specified in subgraph yaml

* Use contract abi to parse event params

* Invoke event handler based on event signature

* Fill event with block and transaction data

* Comment missing fields in block and transaction data

packages/graph-node/test/utils/index.ts

@@ -0,0 +1,31 @@
+//
+// Copyright 2021 Vulcanize, Inc.
+//
+
+import { EventData } from '../../src/utils';
+
+export const ZERO_ADDRESS = '0x0000000000000000000000000000000000000000';
+export const ZERO_HASH = '0x0000000000000000000000000000000000000000000000000000000000000000';
+
+export const getDummyEventData = (): EventData => {
+  const block = {
+    hash: ZERO_HASH,
+    number: 0,
+    timestamp: 0,
+    parentHash: ZERO_HASH
+  };
+
+  const tx = {
+    hash: ZERO_HASH,
+    index: 0,
+    from: ZERO_ADDRESS,
+    to: ZERO_ADDRESS
+  };
+
+  return {
+    block,
+    tx,
+    eventParams: [],
+    eventIndex: 0
+  };
+};