[PATCH 1/2] t5100: make rfc822 comment test more careful

When processing "From" headers in an email, mailinfo "unquotes" quoted strings and rfc822 parenthesized comments. For quoted strings, we actually remove the double-quotes, so:

  From: "A U Thor" <someone@example.com>

become:

  Author: A U Thor
  Email: someone@example.com

But for comments, we leave the outer parentheses in place, so:

  From: A U (this is a comment) Thor <someone@example.com>

becomes:

  Author: A U (this is a comment) Thor
  Email: someone@example.com

So what is the comment "unquoting" actually doing? In our code, being in a comment section has exactly two effects:

  1. We'll unquote backslash-escaped characters inside a comment
     section.

  2. We _won't_ unquote double-quoted strings inside a comment section.

Our test for comments in t5100 checks this:

  From: "A U Thor" <somebody@example.com> (this is \(really\) a comment (honestly))

So it is covering (1), but not (2). Let's add in a quoted string to cover this.

Moreover, because the comment appears at the end of the From header, there's nothing to confirm that we correctly found the end of the comment section (and not just the end-of-string). Let's instead move it to the beginning of the header, which means we can confirm that the existing quoted string is detected (which will only happen if we know we've left the comment block).

As expected, the test continues to pass, but this will give us more confidence as we refactor the code in the next patch.

Signed-off-by: Jeff King <peff@peff.net>
---
I did this as a separate patch so it is easy to see that the existing
code already passes the test (i.e., our refactor is a true noop in terms
of behavior, and not fixing or breaking anything).

 t/t5100/comment.expect | 2 +-
 t/t5100/comment.in     | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)