I currently have a project with the following .travis.yml file:

language: python
install: "pip install tox"
script: "tox"

Locally, tox properly executes and runs 35 tests, but on Travis CI, it runs 0 tests.

More details: https://travis-ci.org/neverendingqs/pyiterable/builds/78954867

I also tried other ways, including:

language: python
python:- "2.6"- "2.7"- "3.2"- "3.3"- "3.4"- "3.5.0b3"- "3.5-dev"- "nightly"
# also fails with just `nosetest` and no `install` step
install: "pip install coverage unittest2"
script: "nosetests --with-coverage --cover-package=pyiterable"

They also could not find any tests.

My project structure is Like This:

- ...
- <module>
- tests (for the module)
- ...

Are the project/folders structured incorrectly?

There was nothing wrong with the folder structure.

It looks like the files on Travis CI are considered executable (logs from https://travis-ci.org/neverendingqs/pyiterable/builds/79049179):

nosetests --verbosity=3
nose.config: INFO: Ignoring files matching ['^\\.', '^_', '^setup\\.py$']
nose.selector: INFO: /home/travis/build/neverendingqs/pyiterable/LICENSE.txt is executable; skipped
nose.selector: INFO: /home/travis/build/neverendingqs/pyiterable/pyiterable/iterable.py is executable; skipped
nose.selector: INFO: /home/travis/build/neverendingqs/pyiterable/readme.md is executable; skipped
nose.selector: INFO: /home/travis/build/neverendingqs/pyiterable/setup.cfg is executable; skipped
nose.selector: INFO: /home/travis/build/neverendingqs/pyiterable/tox.ini is executable; skipped
nose.selector: INFO: /home/travis/build/neverendingqs/pyiterable/tests/test_iterable.py is executable; skipped

I changed tox.ini to run nosetests with --exe (nosetests --exe --with-coverage --cover-package=pyiterable), based on Run all Tests in Directory Using Nose. After fixing some non-related errors, I was able to get the tests to run @ https://travis-ci.org/neverendingqs/pyiterable/builds/79049983!