CALAIS, France (Reuters) - France will test run for a month measures it has prepared for Britain’s exit from the European Union so that companies are fully prepared ahead of Britain leaving at the end of October, including if it goes with no withdrawal deal, a government minister said on Friday.

Gerald Darmanin, who is in charge of customs, met Michael Gove, the British minister in charge of coordinating “no-deal” Brexit planning, in Calais on Friday to show how France is preparing for the British departure, due to take place on Oct. 31.

For one month the French authorities will act as if Brexit has occurred to make sure they are ready by the end of October, Darmanin said.

“We are getting ready for the worst,” he said. “We are preparing for a no-deal Brexit, which is the likeliest hypothesis as of today,” he said. He did not give a specific date for the start of the test run.

British Prime Minister Boris Johnson, who took office last month, has promised to take the country out of the bloc on Oct. 31 regardless of whether a divorce deal that would smooth the way has been agreed.

Businesses have been warning of long tailbacks for lorries transporting goods between mainland Europe and Britain. The British government has said most goods from the EU will be allowed into Britain without full customs checks for at least three months if there is a no-deal Brexit.

Darmanin said some 700 extra customs officers have been drafted in and authorities will also introduce online border declarations forcing companies to announce their goods prior to arriving at the border.

“You are in Grenoble (eastern France), you are a small or medium-sized company, you export to Britain and so you now declare everything online,” he said.

When all the paperwork is done ahead of time on line, trucks will be able to move fast through the border, he said.

He said his services are ready to deal with the new paperwork, the new taxes and the additional controls that will be set up.

“We want to make things as painless as possible,” he said. The automation and digitalization of the processes will make traffic fluid near the country’s ports and there will not massive traffic jams in Calais, he said.

French authorities spent 6 million euros to build new buildings and parking lots in the town and also set up new infrastructure in other ports such as Le Havre or La Rochelle.

France is the EU’s biggest agricultural producer and exports large amounts of wine, spirits and dairy products to Britain, while relying on its neighbor’s waters to sustain its fishing industry.