In many ways, the fundamentals of assessment or the same at any level. You determine objectives, design an assessment to asses those objectives, and interpret the results. The main difference is that adults are more capable of understanding their results at a high level, and incorporating feedback about their performance.
Adult education is a broad field, but in general the assessments are based on outcomes. We want the adults to be able to do something. So we need to create an assessment that shows us what they can do. There are two types of assessments: formative and summative. A formative assessment is used during instruction, and the results are used to reteach material that was not successfully learned, or move on to the next level. In summative assessment, the goal is to see what has been learned.
Authentic or practical assessments are most useful at the adult education level. If you are teaching an early childhood education class, for example, you can have the students create a lesson plan for how they would teach a preschool class. You will be able to tell if they understand the basics by what they produce.