HACKING

Hacking
=======

This is the developer documentation for
https://github.com/dgoodwin/tito

Python versions
---------------

Tito supports Python versions 2.4 (RHEL 5) and up.
See http://docs.python.org/dev/howto/pyporting.html
and http://python3porting.com/differences.html
and https://docs.python.org/3.0/whatsnew/3.0.html
for tips on writing portable Python code.

In particular, you must capture exceptions in a way that's
compatible with both python 2.4 and 3.x. For example:

    try:
        raise Exception()
    except Exception:
        import sys
        exc = sys.exc_info()[1]
        # Current exception is 'exc'.
        pass


Tests
-----

### Docker test harness

To run all tests on all supported platforms:

    yum -y install docker
    systemctl enable --now docker.service
    usermod -aG docker <your-username>

Log out and log in to refresh your secondary group.
Then run from the root of the project:

    hacking/runtests.sh

If any test fails, the script exits non-zero.
To get a zero exit status, all tests must pass
or be skipped.

The above script runs a test harness based on
docker containers and takes several minutes to run
on the first build (or if you remove the images).

Expected output resembles:

    -snip copious output-
    =====================
    Summary
    /tmp/titotest-centos-6-python.out     : OK (SKIP=1)
    /tmp/titotest-fedora-25-python3.out     : OK

You can then review the output, such as:

    $ grep SKIP: /tmp/titotest-*.out
    /tmp/titotest-centos-6-python.out:... SKIP: git-annex '3.20120522 ' is too old

After you run the test harness the first time,
you can optionally create and enter a container like so:

                 .--- remove container when done (not image)
                 |
                 |   .--- interactive
                 |   |  .--- tty
                 |   |  |  .---- mount current workdir into container
                 |   |  |  |                    .---- name of image
                 |   |  |  |                    |                 .-- get a shell
                 |   |  |  |                    |                 |
    docker run --rm -i -t -v $PWD:/home/sandbox titotest-centos-6 /bin/bash


Note about the sandbox: By default, the docker container is a
read-only execution environment to protect your source from changes.
If you are comfortable with LXC, you can override it to provide
an authoring environment, too.


### Workstation tests

To run all tests, install these packages:

* python-nose,  python-pep8,  python-mock (for epl-6 and fedora) and rpm-python
* python3-nose, python3-pep8,  python3-mock (for epl-6 and fedora) , and rpm-python3
* createrepo_c
* git-annex

For epel-5:
There is also a need to install additional library via pip (pip install mock)
for python 2.4 - 2.7 (in case you don't have pip, install via yum python-pip package)
* mock

Then from the root of the project:

    python  ./runtests.py -vv
    python3 ./runtests.py -vv


### Advanced

When developing code for tito there are a couple ways you can test:

"bin/tito-dev" is a script that will run code from the local checkout
rather than what is installed on the system.

And of course, you can always use the installed tito to replace
itself with a test build of the latest *committed* code in your
git HEAD.

    tito build --rpm --test -i

If you screw anything up inside tito itself, you can just:

    rpm -e tito
    yum install tito


Code style
----------

Python3 does not allow mixing tabs and spaces for indentation.
http://docs.python.org/3.3/reference/lexical_analysis.html

You can force your editor to do the right thing by installing
a plugin for your editor from http://editorconfig.org/#download

For example, add the EditorConfig plugin for vim like this:

    cd /tmp/
    wget https://github.com/editorconfig/editorconfig-vim/archive/master.zip
    unzip master.zip
    mkdir ~/.vim
    cp -r editorconfig-vim-master/* ~/.vim/