#!/bin/bash

# Do all the work in /tmp
    $ cd /tmp

# Testing presence of Mercurial
    $ hg --version
re: Mercurial Distributed SCM \(version [\d.]+\)
    (see http://mercurial.selenic.com for more information)
    
re: Copyright \(C\) [\d-]+ Matt Mackall and others
    This is free software; see the source for copying conditions. Ther
+e is NO
    warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
+ PURPOSE.

# Creating a repository
    $ mkdir foo
    $ cd foo
    $ pwd
    /tmp/foo
    $ hg init
    $ echo "this is a file" > content
    $ cat content
    this is a file
    $ hg add content
    $ hg st
    A content
    $ hg commit -m "created repo and added a file"

# Checking that everything looks good
    $ hg log
re: changeset:   0:[a-f0-9]{12}
    tag:         tip
    user:        Fabrice Gabolde <fabrice.gabolde@uperto.com>
re: date:        .*
    summary:     created repo and added a file
[download]

Lines starting with $ are shell commands, the others are expected output. There are facilities for globs/regexes, comments, etc (not everything demonstrated here). The file above gives me:

# cd /tmp
# hg --version
ok 1 - regex match of 'Mercurial Distributed SCM \(version [\d.]+\)'
ok 2 - literal match of '(see http://mercurial.selenic.com for more in
+formation)'
ok 3 - literal match of ''
ok 4 - regex match of 'Copyright \(C\) [\d-]+ Matt Mackall and others'
ok 5 - literal match of 'This is free software; see the source for cop
+ying conditions. There is NO'
ok 6 - literal match of 'warranty; not even for MERCHANTABILITY or FIT
+NESS FOR A PARTICULAR PURPOSE.'
# mkdir foo
# cd foo
# pwd
not ok 7 - literal match of '/tmp/foo'
#   Failed test 'literal match of '/tmp/foo''
#   at lib/Lembas.pm line 87.
#          got: '/home/fgabolde/work/Lembas'
#     expected: '/tmp/foo'
# hg init
# echo "this is a file" > content
# cat content
# STDERR: cat: content
# STDERR: : No such file or directory
[download]

... and it all goes downhill from there, because there are other issues with the code. (The full script is there just to show people what I'm working on and hopefully garner criticism as a side-effect; in reality I have a test on pwd right after cd /tmp and it fails as well.) The foo directory doesn't seem to be created anywhere (says find / -iname foo) either, but cd or mkdir don't complain at all (like cat does at the end)