Prevention of double loading

Author: ledsun

ext/js/lib/js/require_remote.rb

@@ -10,6 +10,7 @@ class RequireRemote
 
     def initialize
       set_base_url
+      @loaded_urls = Set.new
     end
 
     # Load the given feature from remote.
@@ -18,11 +19,17 @@ def initialize
     # Maps like import maps will be used.
     def load(relative_feature, use_maps: false)
       location = get_location(relative_feature)
+
+      # Do not load the same URL twice.
+      return false if @loaded_urls.include?(location.url[:href].to_s)
+
       response = JS.global.fetch(location.url).await
 
       if response[:status].to_i == 200
         code = response.text().await.to_s
         eval_code(code, location)
+        @loaded_urls << response[:url].to_s
+        true
       else
         raise LoadError.new "cannot load such url -- #{location.url}"
       end

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

@@ -61,7 +61,40 @@ if (!process.env.RUBY_NPM_PACKAGE_ROOT) {
     });
   });
 
-  test.describe('JS::RequireRemote#load', () => {
+  test.describe("JS::RequireRemote#load", () => {
+    test("JS::RequireRemote#load returns true", async ({ page }) => {
+      const resolve = await resolveBinding(page, "checkResolved");
+      await page.goto(
+        "https://cdn.jsdelivr.net/npm/ruby-head-wasm-wasi@latest/dist/",
+      );
+      await page.setContent(`
+      <script src="browser.script.iife.js"></script>
+      <script type="text/ruby" data-eval="async">
+        require 'js/require_remote'
+        JS.global.checkResolved JS::RequireRemote.instance.load 'error_on_load_twice'
+      </script>
+     `);
+      expect(await resolve()).toBe(true);
+    });
+
+    test("JS::RequireRemote#load returns false when same gem is loaded twice", async ({
+      page,
+    }) => {
+      const resolve = await resolveBinding(page, "checkResolved");
+      await page.goto(
+        "https://cdn.jsdelivr.net/npm/ruby-head-wasm-wasi@latest/dist/",
+      );
+      await page.setContent(`
+      <script src="browser.script.iife.js"></script>
+      <script type="text/ruby" data-eval="async">
+        require 'js/require_remote'
+        JS::RequireRemote.instance.load 'error_on_load_twice'
+        JS.global.checkResolved JS::RequireRemote.instance.load 'error_on_load_twice'
+      </script>
+     `);
+      expect(await resolve()).toBe(false);
+    });
+
     test("JS::RequireRemote#load throws error when gem is not found", async ({
       page,
     }) => {

packages/npm-packages/ruby-wasm-wasi/test-e2e/support.ts

@@ -30,7 +30,13 @@ export const setupProxy = (context: BrowserContext) => {
       relativePath,
     );
 
-    if (fs.existsSync(mockedPath)) {
+    if (relativePath.match("error_on_load_twice.rb")) {
+      route.fulfill({
+        body: `raise 'load twice' if defined? ALREADY_LOADED
+               ALREADY_LOADED = true`,
+        contentType: "text/ruby",
+      });
+    } else if (fs.existsSync(mockedPath)) {
       route.fulfill({
         path: mockedPath,
       });