Yes, in order to make sure that they've not only read but also understood it, you need to test their reading comprehension. BTW, reading comprehension tests are actually tests of knowledge, please see: https://www.nytimes.com/2017/11/25/opinion/sunday/how-to-get-your-mind-to-read.html
A suggestion: The most valid & reliable reading comprehension test formats I know of are cloze deletion tests: https://en.wikipedia.org/wiki/Cloze_test There's a Moodle question type for creating them: https://docs.moodle.org/38/en/Embedded_Answers_(Cloze)_question_type The codes may look a bit complicated at first but in most cases, it's fairly repetitive & something that's quick & easy to copy & paste elements together with a text editor & then copy the whole text into a Moodle question. It's much quicker than designing multiple choice question tests. The most valid & reliable type is called the c-test, but Moodle's
Embedded Answers Cloze question type is unsuitable for creating those. They're also a lot of work to create manually.
For testing subject matter content knowledge, I suggest creating "strategic" cloze deletion tests, where subject matter key words/terms are selected to be blanked/deleted & the students have to type in the blanked words. Always use separate blanks for each word.
You can also automate finding the keywords with corpus tools, e.g. https://www.sketchengine.eu/. To do this, you need to create a corpus, i.e. a collection of plain text files with all the texts that the students have to read & upload them, so that the corpus analysis tools can accurately select the right keywords/terms. This requires a paid account but IMHO the benefits in time saved alone far outweigh the cost. There's no need to do this if you've already systematically created a course glossary.
I hope this helps!