The office of the prime minister said Thursday that Sophie Grégoire Trudeau had begun experiencing a low-grade fever and other mild flu-like symptoms, prompting the test.
Protesters have blocked key railways, shutting train traffic in much of the country. Demonstrators are trying to stop a pipeline project being built through the lands of the Wet'suwet'en people.
After many denials, Iran's admission that it accidentally downed a Ukrainian plane was cautiously embraced by world leaders as a "step forward." Back in Tehran, protesters' reaction was far angrier.
The prime minister, whose Liberals lost their parliamentary majority in Monday's vote, says he will lead a minority government. Trudeau vowed to continue his policies despite the election setback.
Trudeau's Liberal Party defeated the Conservatives, but still fell short of an outright majority. It will need to reach out to smaller rival parties to form a new government.
"Darkening your face ... is always unacceptable because of the racist history of black face," Trudeau said, even as another image surfaced apparently showing him wearing dark makeup.
Prime Minister Justin Trudeau first approved the project, which is opposed by many environmental groups, in 2016, but Tuesday's announcement means construction can begin later this year.
Canada's prime minister said he was unaware of miscommunication that unfolded, leading his former attorney general to say she was pressured in the case of a firm charged with bribery and fraud.