Test is a noun, synonymous with exam, not a verb. I know I didn't learn the details of language well at primary school, but I do recall being told that a verb was an action. The verb would be "take"; what is it you take ? A test.
At first I wondered why it seemed to translate as Tomorrow I have a 'test Chinese', whereas I expected it to be a 'Chinese test'; thanks to others here for explaining that kao is the verb "to test". Mystery solved. Tomorrow I have to [sort of 'be tested'] in Chinese.