These tests might be graded or they might not be graded. The purpose of these tests are not to get a grade, but instead to see what students know and what students are able to do. These are the tests that teachers really care about; and they are the tests that students actually like because they actually give students information about what they have learned.
The best part is that these "tests" might not even look like tests. They might be one question at the end of the class that students answer (verbally or in writing). It might be a game that students play in class that requires them to answer questions about current lesson topic--and earn points for their team! It might be a mini-project in which students are given a situation that they have to make sense of and then decide what to do next.
Formative assessments are a necessary part of the learning process. It is unlikely that every students will learn and understand every lesson in the every class every day. It takes trial and practice and support and discussion and mistakes and "try again" and more discussion and (yes) formative assessments every step of the way so that teachers and students can get information on what they know and don't know.
Schools are supposed to be about learning. Maybe someday, the "grading" part of school will go away and the only part that will remain will be the learning part.
I hope to be here when that happens.