1 files changed, 36 insertions, 0 deletions
diff --git a/js/src/jit-test/tests/watchtower/property-modification.js b/js/src/jit-test/tests/watchtower/property-modification.js
new file mode 100644
index 0000000000..993cb5bdf8
--- /dev/null
+++ b/js/src/jit-test/tests/watchtower/property-modification.js
@@ -0,0 +1,36 @@
+function getLogString(obj) {
+    let log = getWatchtowerLog();
+    return log.map(item => {
+        assertEq(item.object, obj);
+        if (typeof item.extra === "symbol") {
+            item.extra = "<symbol>";
+        }
+        return item.kind + (item.extra ? ": " + item.extra : "");
+    }).join("\n");
+}
+
+function testBasic() {
+    let o = { a: 10 };
+    addWatchtowerTarget(o);
+
+    // modify-prop: a
+    o.a = 12;
+    let p = { a: 15 };
+
+    // modify-prop: a
+    Object.assign(o, p);
+
+    // change-prop: a
+    Object.defineProperty(o, "a", { value: 19 });
+    let log = getLogString(o);
+
+    assertEq(log,
+        `modify-prop: a
+modify-prop: a
+change-prop: a`);
+}
+
+for (var i = 0; i < 20; i++) {
+    console.log(`Iteration ${i}`);
+    testBasic();
+}