1 files changed, 49 insertions, 0 deletions
diff --git a/js/src/jit-test/tests/debug/Frame-onStep-generator-resumption-03.js b/js/src/jit-test/tests/debug/Frame-onStep-generator-resumption-03.js
new file mode 100644
index 0000000000..3b2e8d2b3a
--- /dev/null
+++ b/js/src/jit-test/tests/debug/Frame-onStep-generator-resumption-03.js
@@ -0,0 +1,49 @@
+// Don't crash on {return:} from onStep in a generator, before the initial suspend.
+
+// This test tries to force-return from each bytecode instruction in a
+// generator, up to the initial suspend.
+
+load(libdir + "asserts.js");
+
+let g = newGlobal({newCompartment: true});
+g.values = [1, 2, 3];
+g.eval(`function* f(arr=values) { yield* arr; }`);
+
+let dbg = Debugger(g);
+
+function test(ttl) {
+    let hits = 0;
+    dbg.onEnterFrame = frame => {
+        assertEq(frame.callee.name, "f");
+        frame.onStep = () => {
+            if (--ttl === 0)
+                return {return: 123};
+        };
+    };
+    dbg.uncaughtExceptionHook = exc => {
+      return {throw: "debugger error: " + exc};
+    };
+
+    let val = undefined;
+    let caught = undefined;
+    try {
+        val = g.f();
+    } catch (exc) {
+        caught = exc;
+    }
+
+    if (val === undefined) {
+        // Tried to force-return before the initial suspend.
+        assertEq(caught, "debugger error: TypeError: can't force return from a generator before the initial yield");
+        assertEq(ttl, 0);
+        return "pass";
+    } else {
+        // Reached the initial suspend without forcing a return.
+        assertEq(typeof val, "object");
+        assertEq(val instanceof g.f, true);
+        assertEq(ttl, 1);
+        return "done";
+    }
+}
+
+for (let i = 1; test(i) === "pass"; i++) {}