Entry restrictions are available at the Federal Foreign Office website.
Travelling from (or returning to) Germany
According to the Federal Ministry of Health's Testing Obligation Ordinance, anyone having spent time in a risk area up to 14 days before their entry into Germany, if requested by the competent health office or a different authority designated, must either provide proof of having tested negative for SARS-CoV-2 or get tested within 14 days of their entry into Germany.
Rules and Exceptions
The entry rule is based on the country from which the traveller is coming from, and not on nationality.
A country or an area is defined as "high-risk" when there are more than 50 new infections per 100,000 people over the last period of seven days.
Mandatory Travel Documentation
No special documentation is required.