1 files changed, 71 insertions, 0 deletions
diff --git a/js/src/jit-test/tests/promise/debugger-reaction-does-not-resolve.js b/js/src/jit-test/tests/promise/debugger-reaction-does-not-resolve.js
new file mode 100644
index 0000000000..48aec08e26
--- /dev/null
+++ b/js/src/jit-test/tests/promise/debugger-reaction-does-not-resolve.js
@@ -0,0 +1,71 @@
+// Promise.race(...) may add a dummy PromiseReaction which is only used for the
+// debugger. Ensure that this dummy reaction can't influence the normal Promise
+// resolution behaviour.
+//
+// See BlockOnPromise when called from PerformPromiseRace for when this dummy
+// reaction is created.
+
+function newPromiseCapability() {
+    var resolve, reject, promise = new Promise(function(r1, r2) {
+        resolve = r1;
+        reject = r2;
+    });
+    return {promise, resolve, reject};
+}
+
+function neverCalled() {
+    // Quit with non-zero exit code to ensure a test suite error is shown,
+    // even when this function is called within promise handlers which normally
+    // swallow any exceptions.
+    quit(1);
+}
+
+var c = 0;
+var g_resolve;
+
+var resolvedValues = [];
+
+function resolveCapability(v) {
+   resolvedValues.push(v);
+}
+
+class P extends Promise {
+    constructor(executor) {
+        // Only the very first object created through this constructor gets
+        // special treatment, all other invocations create built-in Promise
+        // objects.
+        if (c++ > 1) {
+            return new Promise(executor);
+        }
+
+        executor(resolveCapability, neverCalled);
+
+        var {promise, resolve} = newPromiseCapability();
+        g_resolve = resolve;
+
+        // Use an async function to create a Promise without resolving functions.
+        var p = async function(){ await promise; return 456; }();
+
+        // Ensure the species constructor is not the built-in Promise constructor
+        // to avoid falling into the fast path.
+        p.constructor = {
+            [Symbol.species]: P
+        };
+
+        return p;
+    }
+}
+
+var {promise: alwaysPending} = newPromiseCapability();
+
+// The promise returned from race() should never be resolved.
+P.race([alwaysPending]).then(neverCalled, neverCalled);
+
+g_resolve(123);
+
+drainJobQueue();
+
+// Check |resolvedValues| to ensure resolving functions were properly called.
+assertEq(resolvedValues.length, 2);
+assertEq(resolvedValues[0], alwaysPending);
+assertEq(resolvedValues[1], 456);