Use icecave/isolator to mock filesystem and getenv.

[nubs]

Discussed in #4, this uses the Isolator class (really just a mock, but its nice to have something to point to) in order to mock out filesystem calls. These changes mean that the actual filesystem is no longer touched when running the tests.

[nubs]

This rmdir call doesn't seem right to me. Shouldn't this be unlink instead as the $fallback isn't a directory and rmdir wouldn't work?

[bcremer]

I created a alternative for this in PR #7, at least for the getenv part.

I'm not certain about your getRuntimeDir() tests.
You tests basically are testing the mocks and the internal order of method calls in the implementation of the method.

The getRuntimeDir method is used to create real filesystem directories and should be testen on a real filesystem.

I added the tests that write to the filesystem to the "filesystem" group in the phpunit tests, so they can be skipped.

In the future I would like to separate the getRuntimeDir() write logik into a separate class that is entirely responsible for creating directories.

[nubs]

You are right about the order of things being tricky. I'd much rather see things split out into something else that could be mocked away more easily without the complicated series of mocks.

But why do you think that it should run against a real filesystem? We don't need to make sure that mkdir actually makes directories, we just need to make sure that getRuntimeDir calls mkdir when a directory doesn't exist.

I wholeheartedly agree that things could be factored out differently in order to reduce the amount of calls that are being made by the function under test.