WASM instance setup (#11)

* Code for running wasm file.

* Add test for wasm exported function.

* Use target names for build files.

Co-authored-by: nabarun <nabarun@deepstacksoft.com>

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

@@ -0,0 +1,17 @@
+//
+// Copyright 2021 Vulcanize, Inc.
+//
+
+import { expect } from 'chai';
+import path from 'path';
+import 'mocha';
+
+import { getExports } from './index';
+
+const WASM_FILE_PATH = '../build/debug.wasm';
+
+it('should execute exported function', async () => {
+  const filePath = path.resolve(__dirname, WASM_FILE_PATH);
+  const { exports } = await getExports(filePath);
+  expect(exports.add(1, 2)).to.equal(3);
+});

packages/graph-node/src/index.ts

@@ -1,3 +1,13 @@
 //
 // Copyright 2021 Vulcanize, Inc.
 //
+
+import fs from 'fs/promises';
+import loader from '@assemblyscript/loader';
+
+const imports = { /* imports go here */ };
+
+export const getExports = async (filePath: string): Promise<loader.ResultObject & { exports: any }> => {
+  const buffer = await fs.readFile(filePath);
+  return loader.instantiate(buffer, imports);
+};