Role of Testers in Agile

Question

I work in a team which has been doing the traditional waterfall method of development for many years. Recently, we've been told that future projects are going to be moving towards an agile (particularly Scrum) methodology. It so happens that my project will be one of the first, so we will essentially be guinea pigs for the next few months to iron out what it takes to make the transition.

The project itself is in a very early stage and we would usually be many months away from releasing anything to the testing team, but now we are going to be working directly with them up front. As a result, I'm concerned as to the role of the testers in such a project at this stage. I have several questions/concerns which hopefully some experienced agile developers could answer:

1. While a developer is coding a task, it is impossible for a tester to test it (it doesn't exist yet). What then is the role of a tester at this point
2. Is the tester now involved in unit testing? Is this done parallel to black box testing?
3. What does the tester do during a sprint where primarily infrastructural changes have been made, that may only be testable in unit testing?

How do the traditional test team members function in your agile project?

Answer 1

In an Agile Team, What Does a Tester Do?
In an Agile team, a tester's job entails not just generating and providing feedback on test status, test progress, and product quality, but also on process quality. Among these activities are:

The Agile Test Strategy must be understood, implemented, and updated.
Define Acceptance Criteria and the Definition of Done in collaboration with Product Owners.
Test coverage measurement and reporting over all relevant coverage dimensions
Making sure that testing tools are used correctly
Creating, deploying, and managing test environments and data
Creating and performing automated tests, as well as reporting to the team
Reporting and resolving defects with the team
Other members of the team are being mentored on testing-related topics.
During release and iteration planning, ensuring that the proper testing jobs are scheduled
Collaborating actively with developers and business stakeholders to explain requirements, particularly in terms of testability, consistency, and completeness.
Actively participating in daily standup meetings, story grooming sessions, and team retrospectives, as well as suggesting and implementing improvements.