when doing test, it shows cannot access

When I doing gradle test, it outputs such error, however I have changed the jdk to 1.8, I have no idea why it still told me such thing. the .class files are come from the jar file. the test code is below.

I think the problem comes form the IDEA as the test can run on my friend's computer. the fies are in the correct folders and the when writing codes IDEA does not show any red lines.