BERLIN—Want to take the bus or train in Germany? You may soon have to provide a negative COVID-19 test or proof of vaccination or recent recovery, as the country becomes the latest in Europe to consider drastic steps to tackle a new rise in cases in the region. This fourth infection wave is challenging a government in transition, with three parties negotiating to form the next cabinet after September’s inconclusive election. The Social Democrats, Greens, and FDP said on Monday they would add harsher measures to their draft law under consideration by the Bundestag (lower house of parliament) to deal with the outbreak. So-called 3G rules requiring a negative COVID-19 test, or proof of recovery or vaccination should apply to public transport as well as workplaces, according to a policy document by the three parties. It was unclear how they would be enforced. “To quickly and forcefully break the fourth …