1 files changed, 79 insertions, 0 deletions
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_async_loading.js b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_async_loading.js
new file mode 100644
index 0000000000..cb9a07142d
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_async_loading.js
@@ -0,0 +1,79 @@
+"use strict";
+
+const server = createHttpServer({ hosts: ["example.com"] });
+
+server.registerPathHandler("/dummy", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Content-Type", "text/html", false);
+  response.write("<!DOCTYPE html><html></html>");
+});
+
+add_task(async function test_async_loading() {
+  const adder = `(function add(a = 1) { this.count += a; })();\n`;
+
+  const extension = {
+    manifest: {
+      content_scripts: [
+        {
+          run_at: "document_start",
+          matches: ["http://example.com/dummy"],
+          js: ["first.js", "second.js"],
+        },
+        {
+          run_at: "document_end",
+          matches: ["http://example.com/dummy"],
+          js: ["third.js"],
+        },
+      ],
+    },
+    files: {
+      "first.js": `
+        this.count = 0;
+        ${adder.repeat(50000)};  // 2Mb
+        browser.test.assertEq(this.count, 50000, "A 50k line script");
+
+        this.order = (this.order || 0) + 1;
+        browser.test.sendMessage("first", this.order);
+      `,
+      "second.js": `
+        this.order = (this.order || 0) + 1;
+        browser.test.sendMessage("second", this.order);
+      `,
+      "third.js": `
+        this.order = (this.order || 0) + 1;
+        browser.test.sendMessage("third", this.order);
+      `,
+    },
+  };
+
+  async function checkOrder(ext) {
+    const [first, second, third] = await Promise.all([
+      ext.awaitMessage("first"),
+      ext.awaitMessage("second"),
+      ext.awaitMessage("third"),
+    ]);
+
+    equal(first, 1, "first.js finished execution first.");
+    equal(second, 2, "second.js finished execution second.");
+    equal(third, 3, "third.js finished execution third.");
+  }
+
+  info("Test pages observed while extension is running");
+  const observed = ExtensionTestUtils.loadExtension(extension);
+  await observed.startup();
+
+  const contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/dummy"
+  );
+  await checkOrder(observed);
+  await observed.unload();
+
+  info("Test pages already existing on extension startup");
+  const existing = ExtensionTestUtils.loadExtension(extension);
+
+  await existing.startup();
+  await checkOrder(existing);
+  await existing.unload();
+
+  await contentPage.close();
+});