Allow to specify branches in the build matrix

[thedrow]

This is useful for example if I want to build only the python3 branch with Python 3.x and PyPy3.
I encountered this use case with: https://github.com/chtd/psycopg2cffi where Python 3 support has not been added to the mainline yet but we should still test it for the relevant branch that provides support for Python 3.

[roidrage]

You can have a different .travis.yml in your separate branches, allowing for different configurations based on the branch, no?

[thedrow]

I'm not sure. I can't find the documentation about it.
Parhaps it is simply a documentation issue.

[roidrage]

You can have differently laid out .travis.yml files in your separate branches to set different configuration settings to try things out, so that should be worth trying out for your use case.

[roidrage]

I'm closing this as the branches option in the matrix would increase complexity of the file and its format, and having different .travis.yml files per branch seems like a reasonable alternative solution.

[thedrow]

But I can't find the documentation about it.

[roidrage]

When you're working on a branch, simply modify the .travis.yml to suit your needs for this specific branch. Every build uses the .travis.yml relevant to this commit, so you can modify it to have different Python versions, different settings in there.

[untitaker]

I think I need this feature to have a different build matrix for pull requests and master pushes.

The full build matrix includes about 40 jobs -- just spinning that many VMs up takes up a serious amount of time. I'd like to give the PR author quick feedback using the stripped down testsuite (which is only one job), while keeping the master branch running on the full testsuite.

[lasote]

For a regular workflow with branches in Github is not an option to maintain different .travis.yml files in different branches, you will be merging and solving conflicts in every feature, release and hotfix branches.
Why don't you enable something more dynamic than a `travis.yml' to describe the build matrix? A ruby/python script would be nice and simpler.

[kennytm]

This feature is now supported via conditional jobs, by using the if entry inside matrix.include. For instance, OP's .travis.yml may be written as:

matrix:
  fast_finish: true
  include:
    - python: 2.6
    - python: 2.7
    - python: 3.2
      if: branch = python3
    - python: 3.3
      if: branch = python3
    - python: 3.4
      if: branch = python3
    - python: 3.5
      if: branch = python3
    - python: pypy
    - python: pypy3
      if: branch = python3

[lasote]

@kennytm thanks for the example. It was exactly what I needed ;)