I gave a long and opinionated tutorial at EuroPython 2017 about how we should do unit testing and validation within a data science scope. The GitHub repository for the course (which is part of my O'Reilly Live Online training) is https://github.com/kjam/data-cleaning-101. I will continue editing and updating the repository with more examples, so feel free to fork or star it to get updates.
The slides for the talk are also available here:
And for those who attended, please give me feedback!