The assertions should check for header values instead of single string,
because when getting a single header value, we get an empty string if
the header is not set or is set to an empty string. So, to make sure a
header is not set we should check the `Values` slice which is `nil` only
if the header is missing.
Signed-off-by: Babak K. Shandiz <babakks@github.com>
This commit replaces `os.Setenv` with `t.Setenv` in tests. The
environment variable is automatically restored to its original value
when the test and all its subtests complete.
Reference: https://pkg.go.dev/testing#T.Setenv
Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>
Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>
