It is interesting that, to the best of my knowledge, there have been no studies that have used dynamic assessment to measure autonomous learning. Dynamic assessment is a procedure that has its origins in Vygotsky’s zone of proximal development and that integrates assessment with instruction. The assessment involves interaction between the assessor and the learner, during which the assessor offers help to the learner with task completion. In this way it is a measure of a learner’s ability to learn, not a static measure of the outcome of that process. The score on a dynamic assessment may be expressed as the difference between the initial performance and the final performance, or the score on the final performance only. Additional measures include learners’ ability to transfer what they have learned to other situations and their ability to complete the task independently. DA is thus future-oriented and learner-oriented and takes into account both the individual and his interaction with the environment. It could thus very well be an excellent way to investigate the independent aspect of autonomous learning, especially if changes in this ability could be measured over time (for example, before and after a course or using a particular resource such as a self-access centre). Has anyone used DA in relation to autonomy?

Here are a couple of useful references:
Matthew E. Poehner (2008). Dynamic Assessment. A Vygotskian Approach to Understanding and Promoting L2 Development. Springer: Educational Linguistics , Vol. 9. ISBN: 978-0-387-75774-2

Poehner, M. E., & Lantolf, J. P. (2005). Dynamic assessment in the language classroom. Language Teaching Research, 9(3), 233-265. doi: 10.1191/1362168805lr166oa.