1 files changed, 35 insertions, 0 deletions
diff --git a/dom/bindings/parser/tests/test_optional_constraints.py b/dom/bindings/parser/tests/test_optional_constraints.py
new file mode 100644
index 0000000000..78e71df544
--- /dev/null
+++ b/dom/bindings/parser/tests/test_optional_constraints.py
@@ -0,0 +1,35 @@
+def WebIDLTest(parser, harness):
+    threw = False
+    try:
+        parser.parse(
+            """
+            interface OptionalConstraints1 {
+              undefined foo(optional byte arg1, byte arg2);
+            };
+        """
+        )
+
+        parser.finish()
+    except Exception:
+        threw = True
+
+    harness.ok(
+        not threw,
+        "Should not have thrown on non-optional argument following "
+        "optional argument.",
+    )
+
+    parser = parser.reset()
+    parser.parse(
+        """
+        interface OptionalConstraints2 {
+          undefined foo(optional byte arg1 = 1, optional byte arg2 = 2,
+                        optional byte arg3, optional byte arg4 = 4,
+                        optional byte arg5, optional byte arg6 = 9);
+        };
+    """
+    )
+    results = parser.finish()
+    args = results[0].members[0].signatures()[0][1]
+    harness.check(len(args), 6, "Should have 6 arguments")
+    harness.check(args[5].defaultValue.value, 9, "Should have correct default value")