Testing positive in Barcelona

These are great questions. There is a great deal of information already available on the Covid travel section of this forum. You may want to look there as well.
I find the UK government websites about what to do if you test positive in a certain country very informative and practical. Here is the site for Spain.
https://www.gov.uk/foreign-travel-advice/spain/coronavirus

Here is what it says:
Testing positive for COVID-19 while in Spain
If you are tested and the result is positive..... You are not required to self-isolate if you have mild or no symptoms but you should wear a mask and avoid crowded spaces.

Hotels and other accommodation providers may have their own COVID-19 protocols in place in the event a guest tests positive. You should abide by any safety measures put in place by your accommodation provider.

You should follow the advice of the local authorities at all times.
Here is the information from Delta
https://www.delta.com/us/en/travel-planning-center/know-before-you-go/us-entry-requirements#:~:text=In%20the%20U.S.%2C%20CDC%20guidelines,have%20recovered%20from%20COVID%2D19.
What happens if the COVID-19 test is positive?
Customers who receive a positive test result will not be able to fly and are advised to follow the guidelines in the country where the test result was received. In the U.S., CDC guidelines state that any customer who tests positive should self-isolate for at least 5 days and delay travel to the U.S. until they have recovered from COVID-19. Internationally, isolation requirements vary, and customers must follow the public health guidelines where they are located before commencing travel.
Other Information:

A certificate of recovery is generally available 10 days after the initial official positive test and would allow a return to the US if you are still testing positive at that time.

You will have to check your specific travel insurance policy to see what it covers. No one here would know that. Many policies do cover this under the category of trip interruption.

I was also researching this. This is great news!
If you are tested and the result is positive..... You are not required to self-isolate if you have mild or no symptoms but you should wear a mask and avoid crowded spaces.
Of course, we'd be very responsible, but not having a mandatory quarantine is reassuring.

Thanks for the help! I ended up testing negative😊

Boots on the ground here:

As @elaine said, you're supposed "to minimize your public exposure" but there's no requirement for self-isolation. If your condition deteriorates, call the Emergency number 1-1-2 (they service in different languages) and they'll instruct you what to do (which hospital to go to, or whether an ambulance is needed, etc).

Needless to say that if you have COVID, out of civic responsibility, only go out if you must during those 10 days, and if you do, wear a mask at all times. These days we are seeing a large number of contagions as the current variant, while mostly mild for those vaccinated, is extremely contagious. Most people I know that have recently caught COVID, spend a couple of days with a high fever and a lot of fatigue but then recover quickly.

BTW, masks in public transportation are COMPULSORY inside the vehicles and ADVISED while waiting at the stations. Also, some businesses (very few though), still also request the use of masks inside their premises.

Keep abreast on the OFFICIAL information channel of the Dept of Health of the Government of Catalonia here: https://canalsalut.gencat.cat/ca/salut-a-z/c/covid-19/?inici=consultats