I have a question on the usage of infinitives in news titles. While infinitives are seemingly used to indicate that something will be happening in the near future in news headlines (as discussed in this question: Infinitive in news headlines), in this headline, it just looks confusing for me:
“Buddy, first dog to test positive for COVID-19 in the U.S., has died”
Can someone please help me understand how the phrase “to test positive” is used in this context?