diff -r 000000000000 -r 6474c204b198 dom/bindings/parser/tests/test_error_colno.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/bindings/parser/tests/test_error_colno.py	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,20 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    # Check that error messages put the '^' in the right place.
+
+    threw = False
+    input = 'interface ?'
+    try:
+        parser.parse(input)
+        results = parser.finish()
+    except WebIDL.WebIDLError, e:
+        threw = True
+        lines = str(e).split('\n')
+
+        harness.check(len(lines), 3, 'Expected number of lines in error message')
+        harness.check(lines[1], input, 'Second line shows error')
+        harness.check(lines[2], ' ' * (len(input) - 1) + '^',
+                      'Correct column pointer in error message')
+
+    harness.ok(threw, "Should have thrown.")