1 files changed, 41 insertions, 0 deletions
diff --git a/js/src/jit-test/tests/debug/Frame-onStep-20.js b/js/src/jit-test/tests/debug/Frame-onStep-20.js
new file mode 100644
index 0000000000..e070037c36
--- /dev/null
+++ b/js/src/jit-test/tests/debug/Frame-onStep-20.js
@@ -0,0 +1,41 @@
+// Stepping should always pause in a frame between two function calls.
+
+let g = newGlobal({newCompartment: true});
+g.evaluate(`
+    class X {
+        constructor() { this._p = 0; }
+        m() { return this; }
+        get p() { return this._p; }
+        set p(value) { this._p = value; }
+    }
+    let x = new X;
+
+    function f() { return 1; }
+    function inc(x) { return x + 1; }
+`);
+
+let dbg = Debugger(g);
+
+// `code` is a snippet of JS that performs two JS calls.
+function test(code) {
+    let hits = 0;
+    let log = "";
+    dbg.onEnterFrame = frame => {
+        if (hits++ === 0)
+            frame.onStep = () => { log += "s"; };
+        else
+            log += "E";
+    };
+
+    g.eval(code);
+    assertEq(log.includes("EE"), false, "should have received onStep between onEnterFrame events");
+    assertEq(log.match(/^s+Es+Es*$/) !== null, true,
+             "should get two calls, with steps before, between, and possibly after");
+}
+
+test("f(); f();");
+test("f() + f()");
+test("inc(f())");
+test("x.m().m()");
+test("new X().m()");
+test("x.p = x.p");  // getter, then setter