1 files changed, 49 insertions, 0 deletions
diff --git a/js/src/jit-test/tests/debug/Frame-onStep-assign-function.js b/js/src/jit-test/tests/debug/Frame-onStep-assign-function.js
new file mode 100644
index 0000000000..5125359292
--- /dev/null
+++ b/js/src/jit-test/tests/debug/Frame-onStep-assign-function.js
@@ -0,0 +1,49 @@
+// Changing onStep while the function is dead is allowed.
+
+load(libdir + "asserts.js");
+
+const g = newGlobal({ newCompartment: true });
+const dbg = new Debugger(g);
+
+let steps = new Set();
+dbg.onDebuggerStatement = function(frame) {
+  // Setting 'onStep' while alive is allowed.
+  steps.add("debugger 1");
+  assertEq(frame.onStack, true);
+  frame.onStep = function() {
+    steps.add("onstep 1");
+  };
+
+  dbg.onDebuggerStatement = function() {
+    // Clear the 'onStep' while dead.
+    steps.add("debugger 2");
+    assertEq(frame.onStack, false);
+
+    // Clearing 'onStep' while dead is allowed.
+    frame.onStep = undefined;
+
+      // Setting 'onStep' while dead is allowed.
+    frame.onStep = function() {
+      steps.add("onstep 2");
+    };
+  };
+};
+
+g.eval(
+  `
+    function myGen() {
+      debugger;
+      print("make sure we have a place to step to inside the frame");
+    }
+
+    const g = myGen();
+
+    debugger;
+  `
+);
+
+assertDeepEq(Array.from(steps), [
+  "debugger 1",
+  "onstep 1",
+  "debugger 2",
+]);