**Expected behavior**
The test should pass.
**Additional information**
The test creates a new directory at `/home/vagrant/Tatoeba/tmp/export_tests/readonly` with mode `0444`, which should ensure that it cannot be written to and the export fails. However, by watching the directory as the test was running, I observed that the directory's actual permissions are `775`. I think this is because `tmp` is [mounted as a synced folder with these permissions](https://github.com/Tatoeba/tatoeba2/blob/2284e7caba68943bbf21191cae3bbbdc9c05467c/Vagrantfile#L22) and apparently the syncing mechanism can't handle subdirectories with different permissions?
I think the best solution would be to stop syncing `tmp` and remove it from the repo while we're at it. (The directory structure held in place by "empty" files is kind of pointless.) But that's under the assumption that `tmp` contains nothing of value and it's fine to lose it when destroying the VM.
To Reproduce
phpunit tests/TestCase/Model/Table/ExportsTableTest
/home/vagrant/Tatoeba/tests/TestCase/Model/Table/ExportsTableTest.php:372