He says, " I'd let you copy off my test" .

他说，“我会让你抄袭我的测试”。

We're happy to copy test it for you.

我们很乐意帮你做效果分析。

That's to copy off someone's test.

那就是抄袭别人的试卷。

To copy off someone's test the means to secretly write down the answers that the other student has written.

抄写某人的测试，偷偷写下另一个学生写的答案。