Allow to read/write on in-memory file system on Web browser

This change mounts an in-memory file system provided by browser_wasi_shim.

Author: kateinoigakukun

packages/npm-packages/ruby-wasm-wasi/src/browser.ts

@@ -1,4 +1,4 @@
-import { Fd, WASI } from "@bjorn3/browser_wasi_shim";
+import { Fd, File, OpenFile, PreopenDirectory, WASI } from "@bjorn3/browser_wasi_shim";
 import { consolePrinter } from "./console.js";
 import { RubyVM } from "./vm.js";
 
@@ -18,7 +18,12 @@ export const DefaultRubyVM = async (
     ([k, v]) => `${k}=${v}`,
   );
 
-  const fds: Fd[] = [];
+  const fds: Fd[] = [
+    new OpenFile(new File([])),
+    new OpenFile(new File([])),
+    new OpenFile(new File([])),
+    new PreopenDirectory("/", {}),
+  ];
   const wasi = new WASI(args, env, fds, { debug: false });
   const vm = new RubyVM();
 

packages/npm-packages/ruby-wasm-wasi/test-e2e/integrations/wasi-binding.spec.ts

@@ -0,0 +1,33 @@
+import { test, expect, Page } from "@playwright/test";
+
+import {
+  setupDebugLog,
+  setupProxy,
+  setupUncaughtExceptionRejection,
+  resolveBinding,
+} from "../support";
+
+if (!process.env.RUBY_NPM_PACKAGE_ROOT) {
+  test.skip("skip", () => {});
+} else {
+  test.beforeEach(async ({ context, page }) => {
+    setupDebugLog(context);
+    setupProxy(context);
+    setupUncaughtExceptionRejection(page);
+  });
+
+  test.describe('WASI browser binding', () => {
+    test("Read/write on in-memory file system", async ({ page }) => {
+      const resolve = await resolveBinding(page, "checkResolved");
+      await page.setContent(`
+      <script src="https://cdn.jsdelivr.net/npm/@ruby/head-wasm-wasi@latest/dist/browser.script.iife.js"></script>
+      <script type="text/ruby" data-eval="async">
+      require "js"
+      File.write("hello.txt", "Hello, world!")
+      JS.global.checkResolved File.read("hello.txt")
+      </script>
+    `);
+      expect(await resolve()).toBe("Hello, world!");
+    });
+  });
+}