Marijuana dispensaries in Oregon are required to have their items tested at a licensed facility. These facilities test for potency, pesticide and microbiological (mold and mildew) in the products.
Here are some local testing labs in Portland:
Green Leaf Labs , Rose City Laboratory, Going Green Labs, Cascadia Labs.
It is important to know what is in your medical marijuana! Thankfully there are plenty of medical marijuana testing facilities that are regulated by the state of Oregon.