1 files changed, 52 insertions, 0 deletions
diff --git a/dom/streams/test/xpcshell/bug-1387503-2.js b/dom/streams/test/xpcshell/bug-1387503-2.js
new file mode 100644
index 0000000000..1678b46649
--- /dev/null
+++ b/dom/streams/test/xpcshell/bug-1387503-2.js
@@ -0,0 +1,52 @@
+// Test uncatchable error when a stream's queuing strategy's size() method is called.
+/* global newGlobal */
+
+let fnFinished = false;
+let g;
+add_task(async function test() {
+  // Make `debugger;` raise an uncatchable exception.
+  g = newGlobal();
+  g.parent = this;
+  g.hit = false;
+  g.info = info;
+  g.eval(`
+    var dbg = new Debugger(parent);
+    dbg.onDebuggerStatement = (_frame, exc) => {hit = true; info("hit"); return null};
+`);
+
+  async function fn() {
+    // Await once to postpone the uncatchable error until we're running inside
+    // a reaction job. We don't want the rest of the test to be terminated.
+    // (`drainJobQueue` catches uncatchable errors!)
+    await 1;
+
+    try {
+      // Create a stream with a strategy whose .size() method raises an
+      // uncatchable exception, and have it call that method.
+      new ReadableStream(
+        {
+          start(controller) {
+            controller.enqueue("FIRST POST"); // this calls .size()
+          },
+        },
+        {
+          size() {
+            // eslint-disable-next-line no-debugger
+            debugger;
+          },
+        }
+      );
+    } finally {
+      fnFinished = true;
+    }
+  }
+
+  fn()
+    .then(() => info("Resolved"))
+    .catch(() => info("Rejected"));
+});
+
+add_task(() => {
+  equal(g.hit, true, "We hit G");
+  equal(fnFinished, false, "We didn't hit the finally block");
+});