Add simulator

Author: andrewosh

README.md

@@ -48,5 +48,15 @@ Once the server's started, you can use the client to create and manage remote Hy
 ### API
 To work with Hyperspace, you'll probably want to start with the [Node.js client library](https://github.com/hyperspace-org/client). The README over there provides detailed API info.
 
+### Simulator
+
+Hyperspace includes a "simulator" that can be used to create one-off Hyperspace instances, which are useful for testing.
+
+```js
+const createHyperspaceSimulator = require('hyperspace/simulator')
+// client and server are instances of HyperspaceServer and HyperspaceClient that can be used for testing.
+const { client, server, cleanup } = await createHyperspaceSimulator()
+```
+
 ### License
 MIT

simulator.js

@@ -0,0 +1,25 @@
+const ram = require('random-access-memory')
+
+const { Server, Client } = require('.')
+
+module.exports = async function createHyperspaceSimulator () {
+  const simulatorId = `hyperspace-simulator-${process.pid}`
+
+  const server = new Server({
+    host: simulatorId,
+    storage: ram,
+    noMigrate: true
+  })
+  await server.open()
+
+  const client = new Client({
+    host: simulatorId
+  })
+
+  return { client, server, cleanup }
+
+  async function cleanup () {
+    if (client) await client.close()
+    if (server) await server.close()
+  }
+}