1 files changed, 60 insertions, 0 deletions
diff --git a/dom/bindings/parser/tests/test_union_nullable.py b/dom/bindings/parser/tests/test_union_nullable.py
new file mode 100644
index 0000000000..d3255a7e05
--- /dev/null
+++ b/dom/bindings/parser/tests/test_union_nullable.py
@@ -0,0 +1,60 @@
+def WebIDLTest(parser, harness):
+    threw = False
+    try:
+        parser.parse(
+            """
+            interface OneNullableInUnion {
+              undefined foo((object? or DOMString?) arg);
+            };
+        """
+        )
+
+        parser.finish()
+    except Exception:
+        threw = True
+
+    harness.ok(threw, "Two nullable member types of a union should have thrown.")
+
+    parser.reset()
+    threw = False
+
+    try:
+        parser.parse(
+            """
+            interface NullableInNullableUnion {
+              undefined foo((object? or DOMString)? arg);
+            };
+        """
+        )
+
+        parser.finish()
+    except Exception:
+        threw = True
+
+    harness.ok(
+        threw,
+        "A nullable union type with a nullable member type should have " "thrown.",
+    )
+
+    parser.reset()
+    threw = False
+
+    try:
+        parser.parse(
+            """
+            interface NullableInUnionNullableUnionHelper {
+            };
+            interface NullableInUnionNullableUnion {
+              undefined foo(((object? or DOMString) or NullableInUnionNullableUnionHelper)? arg);
+            };
+        """
+        )
+
+        parser.finish()
+    except Exception:
+        threw = True
+
+    harness.ok(
+        threw,
+        "A nullable union type with a nullable member type should have " "thrown.",
+    )