1 files changed, 39 insertions, 0 deletions
diff --git a/devtools/server/tests/xpcshell/test_nesting-01.js b/devtools/server/tests/xpcshell/test_nesting-01.js
new file mode 100644
index 0000000000..6c5e518d89
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_nesting-01.js
@@ -0,0 +1,39 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Test that we can nest event loops when needed in
+// ThreadActor.prototype.unsafeSynchronize.
+
+add_task(
+  threadFrontTest(async ({ threadFront, client }) => {
+    // Reach over the protocol connection and get a reference to the thread actor.
+    // TODO: rewrite the test so we don't do this..
+    const thread = client._transport._serverConnection.getActor(
+      threadFront.actorID
+    );
+
+    test_nesting(thread);
+  })
+);
+
+function test_nesting(thread) {
+  let currentStep = 0;
+  const p = new Promise(resolve => {
+    executeSoon(function() {
+      // Should be on the first step
+      Assert.equal(++currentStep, 1);
+      // We should have one nested event loop from unsfeSynchronize
+      Assert.equal(thread._nestedEventLoops.size, 1);
+      resolve(true);
+    });
+  });
+
+  Assert.equal(thread.unsafeSynchronize(p), true);
+
+  // Should be on the second step
+  Assert.equal(++currentStep, 2);
+  // There shouldn't be any nested event loops anymore
+  Assert.equal(thread._nestedEventLoops.size, 0);
+}