[ANNOUNCE] git-test: run automated tests against a range of Git commits

[Michael Haggerty <mhagger@alum.mit.edu>]

I just released ⁠⁠⁠⁠`git test⁠⁠⁠⁠`, a script for running automated
tests across a range of Git commits and keeping track of the results in
git notes:

    https://github.com/mhagger/git-test

This is a script that I've been using in one form or another for years
and I find it really handy [1].

`git-test` is meant for people who want *all* of their commits (not just
the branch tip) to pass their automated tests.

Tl;dr: How to use `git test`

1.  Define the test you want to run. The string can be any shell
    command:

        git test add "make -j8 && make -j16 test"

2.  Create a separate linked worktree in which to run your tests:

        git worktree add --detach ../test HEAD

3.  Create a terminal window and `cd` to the directory containing
    the testing worktree, and run the test against all of the commits
    on your branch:

        cd ../test
        git test range master..mybranch

    If any of the commits are broken, `git tree` will display the
    error then stop with that commit checked out.

4.  As you work, whenever you want to test new commits, go to the
    testing terminal window and run the same command again:

        git test range master..mybranch

    `git test` is smart enough to remember which commits (actually,
    trees) have already been tested and only run the test against
    commits that have been changed or added. And since the tests are
    run in a different worktree, you can continue working in your
    main working directory while the tests run.

It is also possible to define more than one test suite in a given
repository, retry tests, etc. Type `git test help` or read the `README`
file [2] for more information.

`git test` stores the test results in git notes (under
`refs/notes/test/<name>`), linked to the commit's tree SHA-1. This means
that test results remain valid even across some kinds of commit
rewriting, like changes to commit metadata or squashing adjacent
commits, and a subset of results even remains valid if a commit is split
or if some commits earlier in a patch series are reordered.

I don't plan to turn this into a gigantic project or anything, but I
find this script really useful so I wanted to put it out in the world.
Feedback and/or pull requests welcome!

Michael

[1] The name sucks, I know :-/
[2] https://github.com/mhagger/git-test/blob/master/README.md