Allow using ci-phpunit-test directly from vendor path

[joshkel]

This avoids having to clutter an application's directory with a copy of ci-phpunit-test.

To implement this, I added a CI_PHPUNIT_TESTPATH PHP constant that gives the location of ci-phpunit-test. It defaults to using application/tests/_ci_phpunit_test if that's present (so the default behavior is the same as previous versions. However, if that directory isn't present, then it looks for a vendor folder next to the application folder.

Is this general approach okay? If so, I can update this PR to update documentation and (if appropriate) to update the Composer version of the installer script.

See these comments under #171.

Thanks!

[coveralls]

Coverage decreased (-16.2%) to 56.624% when pulling abeb30d on joshkel:use-from-vendor into e38a140 on kenjis:master.

[joshkel]

I updated the PR to fix a couple of bugs and to keep the code coverage from decreasing (as requested by CONTRIBUTING.md).

I improved the code coverage by perhaps cheating: I had to add additional path handling to CIPHPUnitTest::init, and CIPHPUnitTest::init always executes, but it isn't tracked by code coverage, so the code coverage percentage decreased. I annotated CIPHPUnitTest::init to exclude it from code coverage; since it's test suite bootstrap code, we know it's executed, but because it's bootstrap code, it runs outside of any coverage tracking.

If you'd prefer that it instead remained tracked (as a reminder/placeholder to perhaps someday test it with mocking) and prefer that I find some other way to improve coverage, please let me know.

[ytetsuro]

I think it is a problem that can be solved by using a symbolic link, but what kind of benefits can the user get?

$ cd application/tests
$ rm -rf _ci_phpunit_test
$ ln -s ../../vendor/kenjis/ci-phpunit-test/application/tests/_ci_phpunit_test/ .

[joshkel]

@ytetsuro The biggest benefit would be getting third-party code out of a project's repository - that makes it easier to separate the developers' own code from third-party dependencies, keeps the repo smaller, etc.

It may also make upgrading to a new version of ci-phpunit-repo easier.

I hadn't thought about using symlinks; thank you for the suggestion. However, it would be nice to have an officially supported solution, and symlinks are not straightforward to enable and use for Windows developers.

[kenjis]

LGTM