1 files changed, 84 insertions, 0 deletions
diff --git a/devtools/client/webconsole/test/browser/browser_jsterm_await.js b/devtools/client/webconsole/test/browser/browser_jsterm_await.js
new file mode 100644
index 0000000000..1c1cc87341
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+++ b/devtools/client/webconsole/test/browser/browser_jsterm_await.js
@@ -0,0 +1,84 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test that top-level await expressions work as expected.
+
+"use strict";
+
+const TEST_URI =
+  "data:text/html;charset=utf-8,<!DOCTYPE html>Web Console test top-level await";
+
+add_task(async function () {
+  // Enable await mapping.
+  await pushPref("devtools.debugger.features.map-await-expression", true);
+
+  const hud = await openNewTabAndConsole(TEST_URI);
+
+  info("Evaluate a top-level await expression");
+  const simpleAwait = `await new Promise(r => setTimeout(() => r(["await1"]), 500))`;
+  await executeAndWaitForResultMessage(hud, simpleAwait, `Array [ "await1" ]`);
+
+  // Check that the resulting promise of the async iife is not displayed.
+  const messages = hud.ui.outputNode.querySelectorAll(".message .message-body");
+  const messagesText = Array.from(messages)
+    .map(n => n.textContent)
+    .join(" - ");
+  is(
+    messagesText,
+    `${simpleAwait} - Array [ "await1" ]`,
+    "The output contains the the expected messages"
+  );
+
+  // Check that the timestamp of the result is accurate
+  const { visibleMessages, mutableMessagesById } = hud.ui.wrapper
+    .getStore()
+    .getState().messages;
+  const [commandId, resultId] = visibleMessages;
+  const delta =
+    mutableMessagesById.get(resultId).timeStamp -
+    mutableMessagesById.get(commandId).timeStamp;
+  Assert.greaterOrEqual(
+    delta,
+    500,
+    `The result has a timestamp at least 500ms (${delta}ms) older than the command`
+  );
+
+  info("Check that assigning the result of a top-level await expression works");
+  await executeAndWaitForResultMessage(
+    hud,
+    `x = await new Promise(r => setTimeout(() => r("await2"), 500))`,
+    `await2`
+  );
+
+  let message = await executeAndWaitForResultMessage(
+    hud,
+    `"-" + x + "-"`,
+    `"-await2-"`
+  );
+  ok(message.node, "`x` was assigned as expected");
+
+  info("Check that a logged promise is still displayed as a promise");
+  message = await executeAndWaitForResultMessage(
+    hud,
+    `new Promise(r => setTimeout(() => r(1), 1000))`,
+    `Promise {`
+  );
+  ok(message, "Promise are displayed as expected");
+
+  info("Check that then getters aren't called twice");
+  message = await executeAndWaitForResultMessage(
+    hud,
+    // It's important to keep the last statement of the expression as it covers the original issue.
+    // We could execute another expression to get `object.called`, but since we get a preview
+    // of the object with an accurate `called` value, this is enough.
+    `
+    var obj = {
+      called: 0,
+      get then(){
+        this.called++
+      }
+    };
+    await obj`,
+    `Object { called: 1, then: Getter }`
+  );
+});