- Add methods to temporarily disable and reenable the code hacker.
The code hacker is causing issues in some tests that perform
write operations to the local filesystem. Since this happens only
in a few cases, the easiest fix is to temporarily disable the
code hacker when that happens. This commit adds two new methods
for that in `WC_Unit_Test_Case`: `disable_code_hacker` and
`reenable_code_hacker`.
These methods use a disabling requests count so that the hacker
isn't enabled before it should. E.g. you call `disable`, then
a helper method that does `disable` and `enable`, then `enable` -
then only the last `enable` will have effect.
- `CodeHacker::add_hack` has now a boolean `persistent` parameter.
Persistent hacks won't be cleared by `clear_hacks`.
- `CodeHackerTestHook::executeAfterTest` will now disable the hacker
only if no persistent hacks are registered.
- The existing `file_copy` method is made static for consistency.
- `CodeHacker::restore` method renamed to `disable` for clarity.
Nestor Soriano