I was recalling, how did I run the test code. Until I found that I had written the snippet. I copy-paste it… and the test code was fail. Something wrong. No changes in the test code since my last commit.

I tried the other test code. Looks OK. I tried to rename the fail test code filename, still no good. So, what’s the problem?

Until I found this stackoverflow question.

So, I tried to import the modules written in the test code via shell. Finally now I know which part of the code that fails to import the library.