How do I set the selected item in a comboBox to match my string using C#?

I have a string “test1” and my comboBox contains test1, test2, and test3. How do I set the selected item to “test1”? That is, how do I match my string to one of the comboBox items?

I was thinking of the line below, but this doesn’t work.

comboBox1.SelectedText = "test1";