I'm trying to say that we will test a product and make sure it works, but I don't know if I should say: "After we finish testing and making sure it works..." or "After we finish testing and make sure it works..." In the first example, "making" and "testing" are the same tense, so it makes sense. But in the second, "make" and "finish" are the same tense, and that also sounds right. Which one is correct? Or are they both correct?
In the first sentence "finish" is the simple predicate, and "testing" and "making" are gerunds functioning as the objects of finish. In the second sentence both "finish" and "make" function as verbs. Both sentences are correct, but the second sentence by using the verb emphasizes the concern with the product working (I would interpret the second sentence as implying doubt about the product's success).
Merriam Webster gerund : an English noun formed from a verb by adding -ing