Moving back to the Development & Reestimation

It's all work in progress, and it's up to the Developers how they get it to Done. Yet it doesn't sound as though they have collective ownership of this work, or of the commiments they make, or of their workflow policies. That's the questionable practice which is likely to have negative impacts.

Let me answer your questions from a practical point of view.

Question 1: A story in the Current Sprint is in 'Test' but the developer wants to move the Story back to the 'Development' during the current Sprint (1 week remaining). Can do we this? Is this a good practice?

• Yes, the team can do that. Furthermore, this action enhances transparency, allowing the team to understand the actual state of the User Story.
• However, it is not considered good practice to move a story back to the backlog, i.e., into the TODO column. It would be odd for a Story to reappearing in the backlog without an attached description after the team has invested time in working on it. Perhaps new insights have been gained, and the User Story needs to be updated, refined, or re-estimated.

Question 2: Can he re-estimate the story after moving back from 'Testing' > 'Development'. Will it have negative impacts?

• Estimating a User Story after moving it from Test to Development may not be meaningful during the sprint. Testing and Development together constitute phases aimed at transforming a User Story into a functional piece that meets DoD criteria. The team should prioritize focusing on the Sprint goal, assuming the Story is part of that goal. 

• However, if the Story cannot be "Done" due to unforeseen challenges, it's acceptable to update the User Story and re-estimate as needed at an appropriate event. Address such cases in the Retrospective to explore how to prevent similar situations in the future, as failing to do so could impact the achievement of the Sprint goal