I use the output of getcwd, realpath C functions, and $PWD environment variable to ensure the output of the pwd is correct.

1. realpath -> absolute path
2. getcwd -> absolute path
3. $PWD -> logical path

There are two positive test cases and one negative test case here.

1. positive test case 1: pwd in the common path.
2. positive test case 2: pwd in the path has soft_link.
3. negative test case3: pwd in the path has broken soft_link.

Problems:

1. In the pwd source code, it also uses the $PWD and getcwd function. My test case also uses this, will it a little duplicate?

After discussing with @bses30074_gmail.com , we will remove the use of get_path.c.