Simon asked a great question about finding an advocacy as a lone tester. I find that if you're going to take the road of being a lone tester, it helps to align yourself with several kinds of people who can support you. It takes a village, in this case, to feel supported as the only tester on the team.

I learned long ago that having a supportive manager can make all the difference. One of my first managers taught me how to speak up early and use my voice. Another manager believed in me and taught me how to celebrate my accomplishments when I worked on hard tasks. The manager you report to can make all the difference as a lone tester. Do they give you hard (but achievable) tasks that will grow your skills and expand your knowledge? Do they work with you when you are blocked and help you figure out what the next good step could be? Do they see the value you're creating when others don't? Hopefully, this is a yes for you. If not, you can find support elsewhere. Having this support from your leader helps so much when working as a lone tester.

This could be anyone in the organization. As the lone tester, you have the opportunity to be a useful source and a listening ear to everyone from sales, customer experience, engineering, and data! When I join a team, I make time to meet different people across departments so that I can hear what their struggles are and where they see the greatest issues in our applications. Learning about a bug that CX deals with often, I can test that functionality as we are developing new features, which will strengthen and help to prioritize work across the board. This builds trust and helps teammates feel like their struggles are visible to somebody. Nobody likes shouting into the void. I can't solve everyone's problems, but I can bring these to light that may not be visible if not reported. Listening to different viewpoints provides me with a clearer understanding of the application, which gives me the ability to test in a deeper and more effective manner. 

Like a goldfish, when properly cared for, you won't stop growing. This means that you will eventually outgrow the environment that you are in. This also means you should take on larger responsibilities and new learnings. Hopefully, you have that in the current role. Regardless of your role, you can continue to grow and learn by contributing and learning from the testing community. Surround yourself with people you look up to. Watch people who are in roles you admire, and if possible, talk to them to find out how you can expand your skill set. Being part of the community can help you when you feel stuck and help you see all the resources that are available to you, right where you are. 

As a lone tester, if you are the only QA on the team, you need to build a team that will provide realistic feedback, help support your growth, and help you see your blind spots. Yes, you are going it alone, but you don't have to be alone on your journey as the lone tester.