tests: add a test runner utility that prints nothing when all tests pass
This will be used to run tests through run-tests, which will expect no output
for a unit test that passes successfully.
The motivation for using unit tests instead of the current Python tests is that
they don't require an output file for comparison and that they're easier to write
because of the available tools from unittest (setup, asserts).
$ hg init rep
$ cd rep
$ mkdir dir
$ touch foo dir/bar
$ hg -v addremove
adding dir/bar
adding foo
$ hg -v commit -m "add 1"
dir/bar
foo
committed changeset 0:6f7f953567a2
$ cd dir/
$ touch ../foo_2 bar_2
$ hg -v addremove
adding dir/bar_2
adding foo_2
$ hg -v commit -m "add 2"
dir/bar_2
foo_2
committed changeset 1:e65414bf35c5
$ cd ../..
$ hg init sim
$ cd sim
$ echo a > a
$ echo a >> a
$ echo a >> a
$ echo c > c
$ hg commit -Ama
adding a
adding c
$ mv a b
$ rm c
$ echo d > d
$ hg addremove -n -s 50 # issue 1696
removing a
adding b
removing c
adding d
recording removal of a as rename to b (100% similar)
$ hg addremove -s 50
removing a
adding b
removing c
adding d
recording removal of a as rename to b (100% similar)
$ hg commit -mb
$ cd ..