add integration testing support

test/integration/integration.test.ts

@@ -0,0 +1,18 @@
+import {assert} from "chai";
+import {helper} from "./helper";
+
+describe("main", () => {
+  it("runs a server and matches the game tick", async function () {
+    for (let i = 1; i < 10; i += 1) {
+      assert.equal(await helper.server.world.gameTime, i);
+      await helper.server.tick();
+    }
+  });
+
+  it("writes and reads to memory", async function () {
+    await helper.player.console(`Memory.foo = 'bar'`);
+    await helper.server.tick();
+    const memory = JSON.parse(await helper.player.memory);
+    assert.equal(memory.foo, 'bar');
+  });
+});