The FAA and Transport Canada have an agreement to accept each other's checkrides.
I'd be interested in seeing a justification for this claim.
From the ATP-CTP AC -
FAILURE OF KNOWLEDGE TEST.
Failure to Pass. Applicants who do not pass the ATP Airplane Knowledge Test must follow the provisions provided in § 61.49.
a.Authorized Instructor. For the purposes of the required retraining, “an authorized instructor” is an instructor that:
b.
(1) Meets the instructor qualifications described in paragraph 10(a) of this AC;
(2) Has completed the ground instructor training requirements in paragraph 10(b) of this AC; and
(3) Is employed by a training provider authorized to provide the ATP CTP.
So it's even worse than failing other writtens, you have to be signed off by an instructor in an ATP-CTP program.